I just finished a test piece of mahogany using the “Frenchy” method. I used Zinsser seal coat and thined it to a 1lb cut. I then applied the first coat, brushing quickly and let it dry. I sanded off the nibs using a 320 grit pad. So far so good….. I applied a second coat in the same fashion. On this one, I had some uneveness where my brush strokes overlapped, but it sanded out in the between coat sanding before coat three. The third cost dried with some noticeable streaks, so I sanded and went to a fourth coat. The fourth coat dried evenly, but little tiny bubbles appeared above each pore in the wood. It sort of reminded me of what happens when an oil finish continues to ooze up oil after it’s been wiped dry, except this was on the entire board. I’m trying to figure out what I can do to prevent this on the final piece. My recoat times were about 10 hours apart. I’d put on a coat, go to work, then apply another when I got back from work etc,etc….
PS…. I sanded off the bubbles with 400 grit lubricated with Naptha and then waxed the test piece. It looks fine, but my final piece is a turned newel and I’d prefer not to have to sand all those nooks and crannies, plus, doing all that sanding creates the risk of sanding through to bare wood on the sharp spots on the turning.
Any thoughts?
Edited 1/6/2008 12:42 pm ET by Quickstep
Replies
You might want to read the can or download the Technical Data Bulletin. They don't recommend thinning, it's designed to be a seal coat. Adding solvent can not only cause evaporation complications but also reduce the amount of shellac needed. Sounds like you are just spreading a mess of alcohol. This is just going to dissolve the existing shellac and get trapped in the pores. The dewaxed issue is more associated with using certain top coats over the seal coat.
If you want to use shellac by brushing or wiping, use a couple of coats of seal coat, sanded as the manufacturer recommends. Then use a heavier cut 3# or 4# to build the surface you want.
http://www.zinsser.com/tech_msds.asp
Beat it to fit / Paint it to match
Quickstep,
Just a couple of questions. Please it's not critism of your approach but you bring up issues which I haven't seen and I'm wondering how we differ which might give me a clue..
Unevenness where brushstrokes overlapped? That to me indicates that the first brush stroke dried before the second brush stroke occurred. Could that have happened? If so the way to correct it is faster application.
Are you a tidy painter? Careful and meticulous?
I'm not, I flood it on because as thinned out as it is it doesn't leave runs or drips..
Next you mentioned air bubbles, The only time I've seen bubbles has been when I used 2 or 3# cut shellac. I've yet to see it when I use my overthinned approach. I will be shellacing some oak tonight and I'll do my level best to replicate your air bubbles issue. I don't wait 10 hours between coats, 15 minutes for the first coat, 30 minutes for the second coat, an hour for the third coat .
Frenchy,
I am normally a tidy painter, but I'm doing my best to abandon that based on reading some of your earlier posts. Honestly, I slopped it on and walked away. On the second coat, I didn't load the brush enough and had to go back to the can, so the stroke afer reloading the brush was probably heavier than the prior stroke. This wasn't significant and sanded out easily. I waited longer before sanding, because after only 1/2 hour, I still had some of the finish making thise gummy balls on the sandpaper a little bit. My shop is cold as a tomb also. Just FYI, for thinner I used Behkol and some n-butyl alcohol. I'm using a Corona Chinex Silk brush.
All that said, the final product was ultimately fine. This is the sweetest finish I've ever seen. It brings a depth to the wood that's unparalleled and the way it feels is, in a word, sensual.
Quickstep,Work in an environment that lets the finish perform as it should. A workshop "as cold as a tomb" is no place to try to apply and rub out finish.When sanding shellac, if it doesn't sand to a fine powder, VERY easily, it hasn't dried. Period.The usual solvent for shellac is ethyl alcohol. If we could get pure ethanol at a reasonable price we'd all use it. But the only usable stuff that's affordable is "denatured," usually with methanol or other organic solvents. Behlen's solvent has other alcohols and is an excellent product, but I don't know why you're using n butyl also.Why in the world are you trying to get shellac to perform under so many crazy conditions? - cold application environment, strange combination of solvents, overly thinned solution. Gees.Over thinning won't hurt anything as suggested above, but it will defeat the primary purpose of applying shellac - to get enough resin on the wood to be able to cover the surface and be rubbed out easily. You are just moving solvent around as was correctly explained above.If you are starting out with a process new to you, the most logical thing to do is start with standard conditions. Once success is gained, then it's time to try "strange" things.Use the Zinser product at its 2# cut concentration. There is overwhelming reason that Zinser supplied it that way. A 2# cut shellac solution is the easiest to use and get excellent results with. Use the Behlen's solvent for clean up or to thin the shellac if it becomes thicker due to evaporation from the jar and work in a properly heated room.Give the shellac even half a chance and it will perform beautifully for you as it has for thousands before you.Rich
Quickstep:
1. Buy shellac flakes and Behlen's Bekohol and mix to a 1# cut. Don't buy premixed shellac. I've yet to buy a can that dries properly.
2. Apply 1st coat with a clean white soft rag balled up and very tight like a pounce bag
3. Keep the temerature reasonable 65 to 75 degrees too cold and you slow things down and too hot you will get bubbles
4. Research French Polishing and follow the methodology. You will not have to do much if any sanding and will wind up with a very smooth finish.
Madison
M2 - can you tell me the volume of flakes to liquid you use for a 1# cut? I don't have a scale to weigh but do mix my own flakes and go by volume with 1/8 cup flakes and 1 cup thinner.
Willy:
I just use a small electronic kitchen scale to measure by weight. I picked it up at a garage sale a few years ago. Tell you what at the end of the day today I'll weigh up a couple small batches and get you the info.
I guess I get pretty picky and find measuring by weight works best for me so I'd encourage you to find a scale but then again I don't suppose the furniture makers in the 17 and 1800's had electronic scales and some of their stuff has held up pretty well!
Let me play with the volumn approach and I'll get it back to you!
Now it's off to the shop.
Madison
"...I don't suppose the furniture makers in the 17 and 1800's had electronic scales..."
I'm pretty sure you're right. ;-)
On the other hand, I'll bet that two-pan balances with a set of weights were at least as common as measuring cups back then.
-Steve
Steve:
Two pan balance.
You're right but not as sexy though! You know no bright chrome and LED lights or keyboard. Ha!
Madison
I would not bet the farm that the Can of Bullseye is the same cut it used to be. The last two I picked up seam a lot thiner and they no longer tell you how to thin them down on the back like the used to (so you have not idea what the cut is anymore)
Doug
Doug,
Steve carefully explained that the last shellac wars.. it's the same cut.. if you look on the can under reducing chart the proportions they give are the same as they've always been.It also says clearly in black and yellow (oops white) 3# cut..
Just so we are clear, The can I picked up (well two of them) does NOT have a mix chart on it. Have you looked at the new style can in the last few weeks? It may give a percent (did not look for that) but it not longers says what the cut is, and it no longer has a chart, and it looks thiner. So if it walks like a duck, and talks like a duck....
I may be over reacting but the only reason I can think of why they would pull the cut info off is because the do not want us to know what it is. Only reason I can think that they do not want us to know what it is would be if they changed it.
Doug
Doug,
Hmmm,
I guess I bought my last can two or three weeks ago but it might be from an old batch.
The date manuf on the bottom of the can says 07 05 07. The reducing chart is on the back side at the bottom to the right of the seam.. (over in the foriegn language part)
We are speaking about Bullseye shellac aren't we? yellow can by Zinsser?
Frenchy and Doug-In any case, it's pretty easy to get the info from Zinsser's site. The Technical Data Sheet for their Bulls Eye 3-pound cut gives these directions:Reduction Directions
Desired cut Mix in a separate container
3-lb. to 2-lb. 2 parts alcohol + 5 parts shellac
3-lb. to 1-lb. 3 parts alcohol + 2 parts shellac
2-lb. to 1-lb. 1 part alcohol + 1 part shellac In addition, the sheet indicates that the sollids by volume is 24% and the solids by weight is 29%
We are talking Bullseye, yes, but in my area the color of the can changed. The label changed (the look of it) the chart went away, anything saying what cut it was went away (may list the percent, I did not look for that) and the contents got thiner. So much in fact that My mother (not a wood worker) and my Buddy (also not a wood worker) both noticed it. It was to the point that I was not sure if needed to thin it at all. (I thined the old stuff down, when used for most aplications).
So you may have an older batch. I am not sure of the date on my cans. But in the case of what I bought they had litterly been put on the shelf the week I bought them. (I know the folks in the store and asked) and I also noticed that all the local Borgs have the new style cans around me. Not sure what the difference is but if they dont tell you what it is anymore I have to think it is for a reason.
Doug
"The last two I picked up seam a lot thiner and they no longer tell you how to thin them down on the back like the used to"
But they still say 29% solids, which (as was discussed previously) is about a 3-lb. cut.
I think they may have changed the solvent composition slightly. That could change the "feel" of the liquid without changing the cut.
-Steve
Edited 1/9/2008 10:38 am ET by saschafer
willy
Since Madison hasn't responded yet, I'll give you a pointer I picked up from Jeff Jewitt's book on Shellac. Take a quart glass jar, like a mason jar. Mark the jar, on the outside, using a magic marker, into 4 approximately equal parts. (This isn't rocket science, so just approximate.) 1 part shellac flakes, and fill the jar up to the top line with alcohol.
Ta Da!! Works great for me.
Shellac, approx. 1 lb. to 1 1/2lb. cut.
Jeff
Thanks Jeff. We'll see what Madison comes up with!!!!!!
willy and Jeff-While you're waiting for Madison, let me pass on some information. I once asked Jeff Jewitt the volume question, and he said a 4-pound cut (with one gallon of solvent) yields 1.4 gallons of mixture. Assuming linearity (and why not?) then a 1-pound cut would imply 0.1 gallons of solids per 1 gallon of solvent, or 9% solids in any volume of mixture.Note that the 9% applies to the *mixture*. So the volume of shellac added to one unit of solvent is 0.099units. (0.099/1.099 = 0.09). I don't know how to get a certain volume of flakes alone (minus the space between them). I suppose grinding them fine would be better than just dumping flakes in a measuring cup.
Quick, I've used SealCoat on many projects, and it works great but you definitely don't want to thin it, as Hammer says! I'd like to suggest that you get one of Jeff Jewitt's books, such as Great Wood Finishes and see how he pads or brushes on shellac. I much prefer that technique to brushing, but brushing's good too if you develop an effective technique.
The Zinnser shellac products are a godsend, glad you found them.
forestgirl,
Seal coat by Zinsser is already thinned to a 1# cut so no you wouldn't thin that more.. Bullseye by Zinsser on the other hand is a 3# cut and that does need thinning or really flawless (and fast) brushing technique. All My over thinning does with Bulls Eye is allows you to very quickly flood the surface eliminating the skill requirement. heck toss a bucketfull on and it will come out run free and drip free.
Actaully in my experiance what happens when shellac turns bad is the shellac flakes are still good it's the alcohol has lost the lite ends of the molecue chain and most likely absorbed some moisture from the air..
You can test that yourself..
Open a can of seal coat shellac (or put a small amount in a jar if you don't want to waste a lot on this test) then put the jar near your shower for a few weeks .. someplace where the humidity of the shower will get in but no water..
Now apply that shellac.
I'm willing to bet you have all the troubles you've come to associate with stale flakes
If you want to "prove" the inverse, take something that has had shellac on it for a very long time.. longer than you would think flakes ever keep. Take some fresh alcohol and desolve the shellac into a rag or whatever. Now reapply that shellac onto something..
Hmmm..... interesting isn't it? Maybe it's not the flakes at all it's the alcohol!
"Seal coat by Zinsser is already thinned to a 1# cut so no you wouldn't thin that more.."
SealCoat is 2-lb., not 1-lb.
"Actaully in my experiance what happens when shellac turns bad is the shellac flakes are still good it's the alcohol has lost the lite ends of the molecue chain and most likely absorbed some moisture from the air.."
Moisture absorption, yes. That's a definite problem with shellac. As for "lost the lite ends of the molecule chain," well, that makes no sense. ;-)
If the shellac is dissolved in a solvent that's a mixture, then it's certainly possible that some components of the mixture will preferentially evaporate first, so that the ratios change, but that by itself can't contribute to the shellac going bad. Even in the absence of water absorption, dissolved shellac does go bad, but that's the result of a slow chemical reaction where the shellac reacts with the solvent to create new compounds, not a change in the solvent itself.
-Steve
Steve,
You got me on the seal coat, I haven't bought it in forever and didn't have a can to check.. I stand corrected.
However if you lose any of the elements of any molecule you change the properties of the chemical. Since the lite ends are so volatile and prone to evaoprate losing a few won't radicaly change the compound but losing a lot will change it's properties.. now contaminate that mixture with moisture and we've really compounded the problem)
(admittedly my chemistry is weak but I believe I am correct because that has been my experiance)
Try my little mini test that I gave to Forestgirl. Get a small open jar of seal coat and set it somewhere near your shower. Close enough so the humidity of the show affects it but no real water gets in. A few weeks later apply that shellac to something and tell me it doesn't act for all the world like stale flakes..
Or try the inverse.. get something that was shellaced a long time ago, long enough that you know the flakes wouldn't still be good.
wipe off the shellac with a rag and alcohol and then reapply the result onto another board.. Yes! it will be very weak but I'll bet it goes on fine..
You're not losing the elements out of any molecules, period. That's simply not what's going on. You can certainly lose the lighter molecules themselves from the mixture (that is, entire molecules, not parts of molecules), if they evaporate preferentially, but the molecules themselves are not changing (except for the aforementioned esterification reaction between the shellac and the solvent).
"Get a small open jar of seal coat and set it somewhere near your shower. Close enough so the humidity of the show affects it but no real water gets in. A few weeks later apply that shellac to something and tell me it doesn't act for all the world like stale flakes.."
I'm not sure what you're trying to demonstrate with that experiment. Yes, water in shellac is bad. We all agree on that already. Whether you put an open jar of shellac in a humid environment or pour a teaspoon of water in, it's all the same. In either case it's the water that does the damage; the evaporation of solvent molecules isn't what causes the problems.
-Steve
Steve
I was combining both like a slightly open can might or a can that has little content and a lot of air.
As for the chemical reaction that occurs as things evoporate I'll accept your statement,, however let a half a can of denatured alcophol evaporate and attempt to use the remaining 1/2 and there will be an issue won't there?
Finally There should be a lot less than a teaspoon full of moisture absorbed by the mixture..
"...however let a half a can of denatured alcophol evaporate and attempt to use the remaining 1/2 and there will be an issue won't there?"
As long as you let it evaporate in a dry environment, I doubt it. Denatured alcohol isn't a very complicated mixture, and its components don't differ much in their rate of evaporation, so what you're left with after half has evaporated is still very similar to what you started with. Of course, if you do the experiment in an ordinary room, you'll end up absorbing quite a bit of moisture as the alcohol evaporates.
"Finally There should be a lot less than a teaspoon full of moisture absorbed by the mixture.."
Over the duration of a single shower, that's certainly true. But if you leave a container of alcohol in humid air long enough, it will eventually reach about 5% water content. That's the point at which an ethanol/water mixture becomes an azeotrope, a fancy word for saying that the two components evaporate and condense in the same proportion, so that the ratio never changes.
-Steve
Steve,
Hopefully I won't trip over myself trying to explain chemistry to you. I imagine this is like the elementary school kid trying to explain phsyics. Oh well, here's my best efforts.
If we let most of a can of alcohol evaporate the residue left will not be true alcohol will it? Won't it a large part be the heavier elements that make up the compound of alcohol? The lighter ends of the compund will evaporate first leaving the heavier ends?
As we take away those elements doesn't the nature of the compound alter?
If we compound the issue by adding water (moisture, humidity, H2O) don't we wind up with something vastly differant from a fresh can of denatured alcohol?
Let's consider the simplest case: Pure ethanol. Put some pure ethanol in an open container, and put that open container in a dry room. Let some of the ethanol evaporate. What's left? Pure ethanol!
Now let's consider a simple mixture, ethanol plus a little bit of methanol. Do the same experiment and let some evaporate. What's left? A mixture of ethanol and methanol! The proportions may not be exactly the same as what you started with, but they will be close.
"Won't it a large part be the heavier elements that make up the compound of alcohol?"
There is no such thing. Ethanol is a single, well-defined chemical compound, and a simple one at that. An ethanol molecule looks like this: H H
| |
H-C-C-O-H
| |
H H
It is a stable compound, meaning that it remains ethanol unless you try really hard to get it to react with something else. Simple evaporation will not change it. Same goes for other alcohols (methanol, propanol, isopropanol, butanol, etc.)
You may be thinking of solvents like naphtha, mineral spirits (paint thinner), turpentine, gasoline, etc. Those solvents are mixtures of dozens or even hundreds of different compounds. If you let those evaporate, then you can indeed get significant compositional changes.
-Steve
Steve,
just reading the can here I assume the ingrediants are in a declining percentage.
ethanol
isopropanol
methyl Isobutyl Ketone
pureshellac
Water
So since alcohol would evaporate faster than most of the above ingredants and people have been know to use cans that aren't completely full or fail to completely seal lids properly it would seem like Zinssers changes properties right in the can) ..
Now I looked all over the cans of denatured alcohol I have But none of them list the contents or what denatures it.
I've read and seen all sorts of things in the past. So maybe that is propritary and it varies from batch to batch based on price and availablity rather than any particular characteristic.. I do know that it used to contain 2% of something..
even using that 2% and assuming that it evaporates at a slower rate than alcohol does don't we at some point wind up with 2% or 4% or even 10%?
"So since alcohol would evaporate faster than most of the above ingredants..."
Because? I don't think the assertion is necessarily true. Shellac itself doesn't evaporate, obviously, but I think the others are comparable. Not exactly the same, of course, so if you really let it go until there's almost nothing left, you'll find some compositional changes.
"even using that 2% and assuming that it evaporates at a slower rate than alcohol does don't we at some point wind up with 2% or 4% or even 10%?"
Not necessarily. Depending on the nature of your brew, you usually end up wih an azeotrope. For example, if you mix water and ethanol, then no matter what your starting concentrations are, you eventually end up with 95.6% ethanol and 4.4% water. You can start with 99% ethanol and 1% water, or with 1% ethanol and 99% water; in either case the final mixture is 95.6% ethanol and 4.4% water. The only exception to this would be if you started out with such a small amount that the whole thing evaporated before it could reach the azeotropic composition.
In the US, you can find the formulas for denatured alcohol (there are several, for different purposes) in the US Code; the relevant section is 27 CFR 21 (you can do a Google search on that). For the formula used by a given manufacturer, you should be able to find that in the MSDS.
-Steve
Steve,
I hope you enjoy this discussion as much as I do..
I think I'm stumbeling around finding a solution as to why flakes don't go bad and alcohol does.
It came to me last night..(excuse the shaggy dog story)
Decades ago I was testing engines to try to help get an engine ready to enter the Indy 500. We had access to a engine dyno. One of the new computer controlled ones and I was trying to baseline the engine.
(another words get it to be repeatable so the results were consistant) I quickly did that on gasolene but when I switched to alcohol the results were always inconsistant. The computer eliminated the variables such as differant air density, humidity, and temp. and any time I switched back to gasolene the thing was spot on!
Yet pull after pull varied by a lot, 2%, 4%, as much as 8% variation which makes all tests meaningless.
In the end what changed was the amount of moisture the alcohol absorbed. The more moisture the lower the horsepower!
That upon reflection is what is happening..
Alcohol absorbs moisture, that's what it does. It will suck it out of the air lacking any other source.. If you seal the lid on a half empty can the half that is filled with air has moisture in it.. the higher the percentage of water in the can the worse the alcohol performs. At some point the alcohol won't even burn it has so much water in it..
Since the ingrediants listed on the side of the can of shellac include water we know that it starts with water.. exactly at what point the water content is too high I don't know..
What I do know is that if I dip my brush in a can of water before I spread a coat of shellac it will make an ugly mess. (and take a long time to dry)...
I do know that when I use my overthinned approach I double the amount of alcohol to water ratio.. which is probably why it performs well consistantly when it's over thinned and why it didn't the times I used it straight from the can.
I won't use this as an excuse for my lousy brushing technique. Which is another thing the over thinned approach helps .
"Alcohol absorbs moisture, that's what it does."
That's very true. I thought we established that a long time ago. ;-)
That's one of the ways that a shellac job can "go bad." The other way is with shellac dissolved in alcohol that has sat on the shelf for too long. As we all know, shellac+alcohol goes bad all by itself, even without the absorption of water. Why? This is the esterification reaction we've also talked about in the past: Slowly, over time, the shellac resin molecules react with the alcohol molecules to form new compounds, ones that don't form a solid film. This reaction is going on all the time, as soon as you add the shellac to the alcohol, but the ester accumulates so slowly that it doesn't cause a problem for several months (or even years, if you've done whatever magic thing Zinsser has done to slow the reaction down even further).
Apparently, dry shellac can go bad, too, but this seems to be temperature related. (And I've never had it happen to me.) I think that as long as you store it close to room temperature, it has an unlimited shelf life. There may be differences in dry shellac's longevity between bleached/unbleached and waxed/dewaxed, too, but I don't have enough experience to say.
-Steve
Steve,
I think one other possiblity with regard flakes..
No experiance either but just a pure guesstimate. I think Flakes can absorb enough moisture sitting on the shelf in a humid shop to go bad..
Your insistence in blaming absorbed water into alcohol as the main culprit for shellac failure is not a reasonable assertion for those with more knowledge than us of chemical reactions. I understand your observation that water ruins the finish if there is water on the brush, but so is for an oil finish. Unfortunately, the discussions end up with matters not directly pertinent to wood finishing. As mentioned, the best example of an azeotrope solution is ethanol (called an ideal solution) because what evaporates is the same composition as the liquid left in the container. It absorbes water if the water pressure is high enough, but do this experiment, take isopropanol (rubbing alcohol) at 70% alcohol and 30% water to prepare flakes or dilute pre-mixed shellac. It will work as well as ethanol and the water content is several times the maximum amount of water ethanol absorbes from the surroundings. There are other, more important factors, making shellac not perform as expected than humidity.
Edited 1/9/2008 1:32 pm ET by woodshaves
woodshaves,
OK,
So what will I learn upon completion of the experiment?
What I was trying to say about dipping my brush in water prior to application of shellac was that the alcohol in the shellac mixture would absorb the water and and make the shellac note perform well.. Am I correct in that would be the result of the experiment you gave?
Probably we are looking at the problem from different perspectives. When you mentioned the brush in water, all I see is a saturated brush (100% water trapped) and if dipped in a shellac solution there is no time for the alcohol/shellac solution to displace the water (incidentally, when shellac is introduced to the alcohol, becomes a nonideal solution with liquid-vapor equilibrium changed and following a different path on Raoult's law, this will not be pertinent to discuss here but may favor less water to be incorporated to the new alcohol/shellac solution). My comment on using 70% isopropyl alcohol for shellac is to convince you that even a large amount of water (that is much more than possibly absorbed from surrounding air) will not affect the shellac. Another interesting aspect of shellac mentioned during all this is that the manufacturer wants to sell a good product, but shellac flakes come from the country of origine as flakes in bulk and the retailer may only re-pack. There are all kinds of impurities that may come with it (from insect parts to vegetable products from the tree where the insect was), all of them may cause a batch to be "bad".
woodshaves,
Did I read that correctly? You are saying that no amount of water added to alcohol will affect the quality of the finish of shellac?
I read the last part when contaminants might cause a batch of flakes to be "bad" and frankly I hadn't considered that.. What you say is true of course.
No, what I noticed is that it requires a large amount of water to alter the ability of shellac to form a film.
My background was in organic chemistry and later on in my career I had some peripheral involvement in manufacturing in the pharmaceutical industry. As a result I wonder whether we are making the wrong assumption what shellac flakes are.
As shellac is prepared from a natural source and the level of chemical and physical consistency as compared to what is required in the pharmaceutical industry is light- years off, I would assume that there is tremendous variation in the chain lengths of the polymers, in the distribution of chain lengths as well as the contaminants from batch to batch and source to source and even season to season. The effect on the usefulness, shelf-life, etc. is not normally an issue for the way it is used. But it might explain why is some cases it would if the batch is at the extreme of the distribution of variations.
:>) How is that for high-jacking the discussion? :>)
Edited 1/9/2008 11:12 am ET by dherzig
"...I would assume that there is tremendous variation in the chain lengths of the polymers, in the distribution of chain lengths as well as the contaminants from batch to batch and source to source and even season to season. The effect on the usefulness, shelf-life, etc. is not normally an issue for the way it is used. But it might explain why is some cases it would if the batch is at the extreme of the distribution of variations."
I'm sure that's true. But it's also true that at least the high-profile finish vendors have a big stake in ensuring the quality of their product, so I would have to assume that there is a reasonable level of quality control going on. But I wouldn't be surprised if there is at least a little bit of "vintage" effect. Next thing you know, they're going to be selling us vintage-dated, single-source shellac from a particular region of India, where the nights are cool and the breeze comes from the southwest....
By the way, the level of consistency required by the pharmaceutical industry isn't always all that high. Look up any naturally-sourced enzyme in the Sigma catalog. The range of biochemical activity for a given quantity is often very wide (example: S2515 - "Superoxide Dismutase from bovine erythrocytes" - 2500-7000 units/mg).
-Steve
Some good points.
Relative to the last point: That material is for laboratory use and not part of a fiinished product. The level of variation and contamination of the final product is usually in the 0.01% level. Moreover the variations in the starting materials are also extremely tight. As a matter of fact the largest part of any New Drug Application is the Chemistry and Manufacturing section to cover all of the regulatory issues. In the laboratory the person using the SOD would probably analyze each batch and adjust the amount used if the kinetics of the reaction were the critical part of the experiment.
I don't mess with pound cuts, etc. I pour some alcahol in a clean jar, add some flakes, keep stirring from time to time & maybe add some more alcahol after straining. I just go by how it looks coming off the brush onto the pc. I do it like Frenchy, verrrry thin.
James
Goodness. All this talk about water in shellac...
What I'd like to know from the shellac experts here is if there is a difference in hardness between unwaxed (Bullseye's Seal-Coat) and "regular," or "wax-included" shellac (Bullseye's regular shellac).
Are several coats of Seal-Coat appropriate for applications where one might use the regular variety? Will it hold up as well? I've been using shellac for years, but never could determine what the durability difference between the two might be.
Zolton * Some people say I have a problem because I drink hydraulic brake fluid. But I can stop any time I want.
The word on the street is that dewaxed shellac is harder and has more long-term durability than waxy shellac. I don't know of any rigorous studies, though. Chemically bleached ("super blonde") shellac is supposedly more fragile than other grades, as the bleaching causes some damage to the resin.
-Steve
Steve,
Thanks for your reply. In thinking about, I guess it would make sense that the dewaxed shellac would be harder and more durable than the waxed kind. After all, wax is softer than the shellac resin, and even in small concentrations would likely affect the final hardness.
Thanks again.. Zolton* Some people say I have a problem because I drink hydraulic brake fluid. But I can stop any time I want.
I read somewhere that adding a few drops of brake fluid makes the shellac even better....
-Steve
Now wait a minute here Steve. Ya don't want him to cut into his stash do ya!?
Regards,Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
Super blonde is still just a variety of orange shellac, with the natural dye removed by more activated carbon filtering. It's the Zinsser Clear that is chemically bleached to the detriment of its durability. Bleached shellac is not available in flakes since in dry form it has a life best measured in hours or days rather than weeks or months. So there isn't a down side in using the super blonde if the project calls for very light color.
Dewaxed shellac is somewhat more difficult to sand than shellac that retains its wax.
"I'm willing to bet you have all the troubles you've come to associate with stale flakes " I think maybe you intended that reply for someone else, Frenchy, as I've never mixed my own flakes. Sorry!forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
forestgirl
OK sorry, I reposted it to Steve..
As you see, the Shellac Wars break out again for the darndest reasons.
For more immediate help, go look at Peter Gedrys' five part video piece in the COMMUNITY section on refinishing a small table with shellac and varnish.
Pretty nice (and educational) to see someone actually do it.
Mike D
P.S. Frenchy got me started back using shellac again. I got good results, too - thanks, Frenchy.
Occasionally now I like to build up a film a little faster than with a 1# cut, so when I do, I use Zinzer's Seal and Coat right out of the can. I'm presently using a foam brush (although I've got much nicer brushes) and get good results with that, too.
Edited 1/7/2008 10:04 pm ET by Mike_D
Edited 1/7/2008 10:39 pm ET by Mike_D
Thanks Mike, I like Frenchy's method of using overthinned shellac. It is very forgiving of poor application and it lets me control the thickness of the film by just adding more coats until I acheive the look I like. I now have three samples - one with just one coat of shellac then wax, one with two coats then wax and one with four coats then wax. I REALLY like the look and feel of the one with just two thin coats then the wax, but I think I'll go with three or four coats to get some extra protection since it's a handrail.
You're welcome.
I'm going to have to recant my earlier statement that I get good results straight from the can. Darn test piece that I just put the 3rd coat on looks like a several day old mackerel. Euuuu! (I was trying using a brush, by the way).
Gonna have to sand that all off and start anew.
I haven't tried the pad method yet. Seems like I otta, since I'm delaying putting anything resembling a finish on my project until I master one of them.
Mike D
Oh, yes. If you go for the foam brush (does work great) - throw the darn thing away after two days - the alcohol started breaking mine down at that point, and I applied a nice finish of little grey-black flecks all over everything when I was shellacking a shop jig that I built.
Edited 1/8/2008 12:27 pm ET by Mike_D
"I haven't tried the pad method yet."
Try it. You'll never look back. The coats are thinner, so it takes more of them, but their smoothness compared to brushing is like the Bonneville Salt Flats vs. the Himalayas.
I'm trying to visualize exactly what a several-day-old mackerel looks like, but my guess is that you either put that third coat on too soon (the second coat wasn't really dry yet), or you "worked" it too much by brushing over the same area more than one once.
-Steve
I've tried the pad methond and I actually like the theory that you have to build up multiple coats because it let's you control the gloss a little more. BUT, in my attempts, I've always had the second coat re-dissolve the first coat and it seemed like I wasn't building any thickenss at all. What was I doing wrong?
Unless I'm doing a French polish, I've found that the second (and subsequent) coats work best with just single swipes across the surface. The pad I use is about 3-1/2" across, and depending on how heavily I "load" the pad, I can get around a 24" stroke without reloading. Let's assume that the panel I'm finishing is 12" square. I'll get my pad all nicely settled in my right hand, then apply a small squirt of 2-lb. shellac from a squeeze bottle with my left hand. I'll take one stroke across the top (that is, farthest away from me) of the panel, then another one 3" down (so there's enough overlap to avoid a dry spot, but no more). Then I'll reload with a little more shellac, and make two more strokes, one 6" down and one 9" down, which brings me all the way to the bottom of the panel.
That's it. As with the Frenchy Method, don't go over it, don't try to fix a dry spot, just don't touch it at all. Let it dry for a while, wipe off any dust that may have fallen on it, then repeat. I typically let it dry for an hour between coats, but that's just because I'm doing other stuff in the interim (like working...). You don't have to wait nearly that long. After you've done several coats in succession this way, you'll have accumulated enough specks of crud in the finish that you'll want to do a light sanding with 320 grit to flatten. Unless I'm in a hurry, I'll apply between three and six coats, let it dry overnight, then sand the next day before continuing with further coats (if I feel the need).
I don't know about "controlling the gloss" with multiple coats. An "off the pad" shellac finish is glossy--that's just the way shellac is--but generally not perfectly flat. You control the gloss by rubbing out: Wet sanding with 600-grit silicon carbide gives you pretty much dead flat; doing the same with 4000 grit followed by some automotive polishing compound gives you a high gloss.
French polishing, by the way, is different because you're rubbing the finish with the pad as it's drying. And you can only get away with that because you're using a lubricant to keep the pad from sticking.
-Steve
"I'm trying to visualize exactly what a several-day-old mackerel looks like" - it looks like it smells - not good! Shiny but definitely not smooth. Like I'd applied a nice shiny glue instead of shellac. Ugly. Ruined what I'd done before. etc., etc, etc.
I may have tried to put it on too soon, since it's really humid right now, but I did wait a full day. I also have a hard time not going over it "just once" from end to end to tip it out. That could have be the screw-up as well.
One interesting thing that I've discovered is that if you get a nice big drop dripped on the work, you have to stop and get that up, let it dry, and then sand the bee-jezzus out of it so that it's little ring of solids is no more. Otherwise it WILL print out again when you put on the next coat. (Everyone already knew that, right?)
Question: When you pad shellac, do you cut the mix from the Zinzer can to a thinner mix? I'm assuming that SealCoat is about #2 cut, but it could be #3 for all I know. Also, do I need to use mineral oil on the pad for the second coat to keep it from sticking? i.e., as if I were french polishing? Have'nt tried that yet, but I've read about it.
Mike D
Edited 1/8/2008 4:20 pm ET by Mike_D
"I also have a hard time not going over it 'just once' from end to end to tip it out."
Don't do that. And if you do do it, at least have the diplomacy not to tell me about it; it makes me wince. ;-)
I use a 2-lb. cut (either SealCoat or something I've mixed up myself). The other Zinsser shellacs are 3-lb., so they do need thinning.
Some people suggest a bit lighter (1-1/2 lb. or thereabouts), but I've never found 2 lb. to be a problem. Since the pad is already wet with alcohol, I suppose the actual cut as the shellac is deposited is a bit lighter than the starting ratio, so how wet your pad is to begin with may affect how easy or hard a given cut is to work with.
You don't need mineral oil for padding, but do understand that a padded shellac finish, just like a brushed one, needs to be rubbed out, as it won't be smooth enough "off the pad" for Fine Woodworking. The difference is that a padded finish is a whole lot easier to rub out (in my experience, anyway). In principle, a properly-applied French polish doesn't require rubbing out, but that takes a lot of practice, and I freely admit that while I've tried, I ain't there yet.
-Steve
And for the ultimate satisfaction in applying ANY kind of finish, God gave us spray equipment.Once learned, even the cheapest gun is so much better than any brushing or padding method (except the last layers of french polish, but that's a WHOLE different ballgame).Anyone who has had the perseverance to stay with spraying until mastering it - getting the angle of the light right, so you perfectly see the layer going down, beginning to end, spraying just enough to cover the wood, never enough to run. Letting it dry - spraying again, putting on exactly the number of layers you want, without worry of disturbing the under coat.When it finally "clicks," there is no faster or more predictable way to lay finish down. You will NEVER do it any other way.Rich
True,
But, one needs a dry, warm in winter (and no open flames please), well ventilated, well lit place to do it where overspray won't ruin every thing else in the space.
Regrettably, we don't all have access to such a space. If I did, I would.
Therefore, (sob!) on with the arcane tools and skills of hand application.
Deeply, deeply deprived in the dim, damp, and poorly ventilated cold, I remain, yours truly...
Mike D :)
Mike,You would not believe the measures some finishers take to make it possible to put down a spray finish in preference to other application methods. Heat, cold, humidity, wind, whatever. Once you get good at it, you look for ways to use it!Rich
I can understand that. I feel that way about my new Veritas Bevel Up Smoother. Can I smooth that for you? 700 year old oak knot? No problem. Lumpy concrete countertop? Just let me change to the 55 degree iron. Hummmmm, I wonder if it would be practical to shave with this in the morning?
Mike D
"When a man has a new hand plane in his hand, all the world looks like it needs smoothing.." or words to that effect. It must be the same for spray equipment. And if it says HVLP on it somewhere, why, geee......Have you seen how smoothly this will put CoolWhip on strawberry shortcake?
:)
Edited 1/9/2008 6:32 pm ET by Mike_D
Rich 14
Let me politely disagree with you..
I probably have a lot more spray painting equipment than you do.. and decades of experiance with spraying.. yet I won't spray shellac!
Takes too much time!
Not the actual spraying.. you are right in that if you have a dedicated space and everything set up it probably is faster..
However I know of few who have such dedicated space..
This forum post is now archived. Commenting has been disabled