After brushing on a 1-lb. cut of shellac on the workpiece, I scuff sanded with 320 girt paper, dipped some #0000 steel wool in mineral spirits and rubbed it on the workpiece in a circular fashion. When the slurry dried I wiped it with a clean cotton cloth.
I saw a lot of fine scratches and swirls in a raking/low angle light, so I repeated the steel wool application and rubbed with the grain. Now I see very fine straight scratches ans some faint hints of small swirls.
Will a coat or two of satin polyurethane hide these scratches, or do I need to do something else first to remove them?
Thanks for the advice,
Brian
Replies
bmyyou,
It's easiest to go back to the shellac. Just make a pad and squirt some shellac on it and, in circular motion, put a thin coat of shellac on. If you want to, you can then sand with a higher grit and repeat the process as many times as you want till it's as polished as you want.
I will suggest however, with a 1 pound cut, I'd put on 3 coats before I started the circular motion action..
Jeff Jewitt has excellent articles on his Homestead Finishing web site about shellac finishes, including how to pad on shellac. BG's idea is a good one, IMHO, but you want to put a little denatured alcohol on the pad before starting with the shellac.
Click here for Jeff's padding article, click here for an index of all articles, including other info about shellac.
If the shellac you used was dewaxed, polyurethane would certainly cover the stratchs left by steel wool, or the 320 grit sand paper. If the shellac still contains it's natural wax, you would need to use a tradtional resin varnish--one that did not contain polyurethane.
Brian,
It's not clear what you are trying to do.
You brushed on a single coat of 1# cut shellac, then abraded with 320 grit followed by 4-0 steel wool. Of COURSE you will be able to see that level of abrasion if you examine in a "raking/low angle light."
What do you mean by "hide these scratches" when you ask about covering that thin, probably broken shellac film with another layer of finish? Given the issue of adhesion that Steve raised regarding your having used shellac containing any natural wax, yes, covering the abraded shellac will "hide" that surface. The surface you will then see will be the dry surface of the final finish, and its appearance will depend on how you have allowed it to dry/harden and whether you have applied any abrasion to it.
What are you trying to accomplish? A satin finish that shows no abrasion marks when viewed critically as with a low angle light?
Rich
I'm trying to get a satin finish on the workpiece - not glass smooth but one that doesn't show high spots or scratches.
The shellac I'm using is dewaxed so I will try padding it on as referenced in a previous post. I have been using 1 lb cuts because I couldn't brush on 2 lb cuts very well on practice boards.
I plan on using a satin polyurethane or a wiping polyurethane for the topcoat.
I'm also having trouble not sanding through the edges of the finish on the workpiece when I scuff sand the shellac coats with 320 grit; would appreciate any advice on how to avoid that.
The ONLY coat of shellac that needs scuff sanding is the last one--the one that will hold the varnish. Shellac itself will bond to itself perfectly with no sanding at all.
To avoid sanding through edges, make sure that you keep the pressure on your sanding block well back from the edges. Also, remember that the edges (arises) should be slightly broken, or rounded before finishing.
As Steve said, the only coat that you need to abrade is the final coat, whatever that is. So if you want a satin finish, it's the final coat of polyurethane that you want to use the steel wool on.But that still begs the question - why are you starting with shellac and applying a final coat of polyurethane? Why not just shellac? Why not just polyurethane?Rich
I see others have asked the same thing. Why aren't you just putting the varnish on--wipe on coats of a non-poly varnish for a beautiful finish. I use satin throughout the finishing applicatons and by carefully keeping the mixture swirled, the particles stay in suspension. If you don't think you can do that, wipe on gloss varnish and finish with a coat of satin. You'll need about 8 applicatons.
Now that you have started with shellac, just finish with the varnish. Using non-poly will keep adherence problems from occurring.Gretchen
Gretchen,
I'm not a very experienced finisher so I'm having some trouble following your suggestions.
I have been lightly scuff sanding with 320 grit after every wiped on coat of 1lb shellac. The workpiece is a desk top, and I believe shellac will show water rings so I was planning to finish with 2 coats of satin poly to avoid that problem. Is there another finish that I can use that is easy to apply and will finish smoothly?
I have rubbed on 2 coats of shellac so far, and I was planning to rub on a few more coats to see if the finish gets smoother. From there, I am going to apply the poly unless there are some better methods.
Thanks for the advice,
Brian
Brian,We are all wondering why you are using 2 finishing materials. There are good reasons to do this under some circumstances, but it's not clear what you are trying to do.Are you intending on sealing the wood with shellac? The fact that you are using 320 grit and 4-0 steel wool on that microscopic shellac layer is what doesn't make too much sense.2 coats of a 1# cut shellac, "rubbed on" will not give enough film thickness to do any abrading at all.Gretchen was suggesting that you apply thinned polyurethane varnish by rubbing or padding it on. This applies very thin layers. If you apply each new layer before the previous has had too much time to cure, bonding will be good. About 24-48 hours for each application is about the right schedule. You will need 6-8 applications to bulid up a usable film of polyurethane varnish using the technique.Again, why don't you explain what you are trying to accomplish?Rich
Rich misunderstands me. I am suggesting using a NON POLYURETHANE varnish, as a wiping varnish for the entire finish. As others have said, you don't need to use the shellac.
Get some NON-poly (you will have to go to a real paint store, not HD or Lowe's), dilute it half and half with mineral spirits and wipe it on. Be done with this.Gretchen
Gretchen,Sorry. And sorry to have further confused this whole issue, which really is so simple!Rich
Edited 8/31/2008 9:29 pm ET by Rich14
Can I use the same padding approach for the wiping varnish as suggested for shellac, or does it require a different method?
A WHOLE lot easier than padding shellac. Dip a lintless cloth or good quality paper towel (with no pattern/embossing) into the thinned varnish and as Howard Acheson often describes, wipe your surface like a worker at Denny's wiping off the breakfast table. I personally like to wipe it with the grain. Let dry a couple of hours and repeat. The first 3 coats will make you think you have made a terrible mistake--they don't look good. Just keep applying coats, giving a very light sanding after 3 and 6. Wipe off with mineral spirits.
Pratt and Lambert #38 is an excellent non-poly varnish.Gretchen
Rich,
I didn't want to confuse others in my original post with background info on the project, but perhaps that will help explain the finish that I'm pursuing.
I'm finishing a maple desk that was stained with a water-based dye, treated with tung oil, then coated with a 1 lb cut of dewaxed Sealcoat shellac; then glazed with Mohawk Van dyke brown glaze. The shellac is supposed to be the seal coat before completing with a topcoat (or more shellac). However, I have read that shellac is not water resistant, and since this is a gift I would like to prevent any unforeseen damage to the finish. It is highly likely that the recipient will drink sodas or other cold drinks while using the desk, and I can't guarantee that they will use a coaster.
So I have been padding on shellac as suggested in the other posts with 1 lb cut of shellac. I read Jeff Jewitt's site before I posted, and I misinterpreted the finish polishing step to use steel wool with wax dipped in mineral spirits. I only used #0000 wool dipped in mineral spirits without wax after 2 coats of 1 lb shellac, and I ended up with the circular scratches as mentioned. Before I realized I missed the wax, I went back over the top with #0000 wool in straight swipes with the grain. That's when I noticed that the top felt smoother to the touch but I could see fine scratches under a raking light.
After reading the posts and growing more confused by all the possible methods and references to other finishes I am not familiar with, I decide to keep padding on the 1 lb cut of shellac as described on Jeff Jewitt's site. I tried to pad the straight 2 lb cut out of the can but kept dragging the pad and it constantly needed recharging. The 1lb cut glides much smoother across the top.
So hopefully you can understand better what I am trying to do. I had anticipated that subsequent coats of Minwax satin polyurethane that I have in the cabinet would cover the scratches after sanding with finer grits between coats. The finish does not have to be a mirror finish, but I would like it to be smooth and durable for it will be used frequently. I will also have to apply the same finish to the nooks and crannies of the base, legs, drawer fronts, hutch that sits on the top, and the stacked bookcase that sits on top of that.
I would appreciate any suggestions you have to correct or continue the finish that I have started. According to Gretchen's post, I should either get P&L or Sherwin Williams non-poly varnish and pad it on to the top (after thinning it), or keep padding shellac, but I would like to have a more water-resistant table top.
bmyyou,(btw, what's your name?!)OK!,Now we know what you're trying to do. It sounds like you have a very good foundation for putting a durable and beautiful finish on that desk. You've gotten confused as you have selected a pretty complex process. However, none of the individual steps in the process is difficult. It's understandable how you've gotten bogged down.You've used shellac which is an excellent sealer/retarder for the glazing step. Shellac is amazing stuff. It not only serves as an intermediate substance, it can be used as the entire final finish.I'm a big fan of shellac and I could tell you how to carry the shellac through for the complete finishing process. But I'm going to recommend that you now switch over to varnish. Shellac is a very durable coating, much more water resistant than some people want to give it credit for, but I don't think it's quite the finish you want on this desk, which probably will get some heavy use.I recommend that you get a quart of Behlen's Rockhard tabletop varnish. Do a Google search, it's available at Woodcraft, Rocklers, Grizzly, and many other sources. This is a high-quality, traditional (phenolic) varnish that is a "short oil" formulation, meaning it cures to a very hard surface. I don't recommend it over bare maple because it will yellow the wood, but you have taken care of that with stain and sealer. It has an slight amber hue as do all oil-based varnishes. Like its label says, its a great finish for surfaces that will get hard use.I would apply the varnish full-strength, after a dilute "wash coat" but I don't think you want to do it that way.The following applies to Rockhard, as well as any other varnish, whether phenolic, alkyd, polyurethane, but not to water-borne or acrylic.This is a wiping varnish method. It's very easy to do, but takes a while. Others will probably add their refinements.Thin the varnish with an equal amount of solvent (mineral spirits or naphtha. If using mineral spirits, get the non-odor kind, the regular stuff smells awful.)Wipe/pad the 50/50 mixture on the wood. Wait 24-48 hours and pad on the next application for 6-8 applications. Every few applications level out any accumulated dust nibs with 320 grit sandpaper on a rubber sanding block. Don't try to level the whole surface. You shouldn't have to as it will be very level as the result of the fact that the thinned varnish has flowed out very evenly with each wipe-on application.By applying every 24-48 hours, each application will bond to the previous. If you wait longer than that, you'll need to scuff sand the hard varnish to encourage adhesion and to avoid "witness lines" that can occur if you sand or otherwise abrade the built-up varnish film.Stop at the next-to-the-last application. Let it cure for a week. Then level out all nibs and irregularities with 320 grit. You should achieve an over-all, even, ground-glass appearance. Then apply the final coat. It should flow on and dry to a smooth, even, luster. It's your call if you want to rub out that final coat with steel wool, then polishing compounds. Probably not, but if you do, wait 3-4 weeks for curing.Rich
Edited 9/1/2008 8:30 am ET by Rich14
OK, now we know where you want to go.
I really like Pratt and Lambert 38 varnish. It will look a hundred times better than any polyurathane once rubbed out. Use two coats straight out of the can. Let first coat dry overnight and scuff sand with 320 grit before applying the second. Don't worry about any fine scratches you have in the shellac, as the varnish will fill them in. Let cure two full weeks, then rub out to a high gloss as I described in my last post. A desk top is not too big a project for this technique, but I'd only take the sides and drawer fronts and legs (if any) to a satin finish. Your call, good luck.
Chris
Edited 9/1/2008 12:05 pm ET by fishnskiguy
One comment not related to whether to use shellac, alkyd varnish or polyurethane as a top coat -
You state that you'd like a (what I interpret to mean) a semi-gloss finish rather than a high gloss finish. There are several ways to achieve that. One is to add a "flatting agent" to the finish (which is done for you with satin or semi-gloss polyurethane). These flatting agents are small crystals that are embedded in the finish, and scatter incoming light and prevent a portion of it from reflecting back at the viewer. More flatting agent results in less gloss.
However, if you're using a finish that doesn't have any flatting agents (like shellac, alkyd varnish, or high gloss polyurethane), how reflective the surface is at the end depends a lot on the surface topography. In other words, if the finish has been rubbed out with a very fine abrasive like Rottenstone or a commercial polishing compound, the surface scratches are very, very fine, the surface itself is very flat, and the result is a mirror finish. One way to achieve a semi-gloss finish is to stop polishing with a coarser grit, whether that's in the form of pumice, 1000 grit sterate sandpaper, or 4 aught steel wool. Doing so leaves scratches that are deeper than if the finish is polished more thoroughly with a finer grit, and a portion of the incoming light will be scattered, which will result in a less than mirror finish.
In other words, it's OK to have tiny scratches in the surface, you just may want those scratches to be a bit finer than 320 grit sandpaper will leave behind. So, you may want to level the finish (whatever that is - poly, varnish or shellac) with 400 grit stearated sandpaper, then progress up through 600, 800, and 1000 grit stearated sandpaper. Clean the stearate (the white powder) off of the surface after each grit, and stop when you achieve the "semiglossness" you desire.
Thanks - I have received a book-load of info from these posts and have learned a lot on achieving a good finish. I am going to try a few of these suggestions on my sample boards before proceeding. And you're right, I'm trying to achieve a decently smooth semi gloss finish, so I will have to sand a bit finer than 320 grit. The biggest mistake I made was "polishing" the top with the steel wool after only a coat or two of 1 lb cut shellac.
Bmyyou - I often use shellac, and its usually a rubbed-out finish. In my case, I don't touch the surface with any sandpaper or other abrasive until I have 6 coats on it. That sounds like a lot, but because it dries so quickly I usually can get 6 coats on in under an hour.
One other comment - you will find that freshly-mixed (and I do mean fresh - not over a couple of weeks old) shellac from flakes will behave the best from a sanding standpoint. I've used Zinsser's before, but I didn't like it. Not only was it expensive, but it was a bit gummy unless I let it dry for several days. The can was definitely "in date", so I interpret some of the poor sanding performance to a bit of wax that's included (the SealCoat formulation, from what I understand, doesn't contain wax).
With freshly mixed de-waxed shellac from flakes, I find that I can sand after letting the first 6 coats dry overnight, though I'll note that I use stearated sandpaper for this task. The non-lubed wet/dry or aluminum oxide papers might not perform quite as well.
You would be surprised at how water resistant shellac is. You would have to build a reasonably thick film to demonstrate this. Using 1 lb. cut will take for ever to get any sort of film, especially if you want to sand each coat. Adjust your mix to 1 1/2 pound cut, and don't sand between coats of shellac. But shellac isn't needed on every finish, only when there is a specific reason--for a particular coloration, to provide a barrier between incompatible materials such as certain stains and particular top coats. Nonetheless, the greatest longevity finish is almost always one that is a single material from sealer to top coat.
There is a very sure method of guaranteeing no white water rings--it's a low technology device called a coaster. Scatter a few around on every susceptible table top and they will be used--put them in a drawer and you're sunk.
What is a good brand of non-poly varnish to use?
How about rubbing it with pumice or rottenstone?
Here is what I have learned, and believe me, it took a while to get it right.
For a really gloss shellac finish apply five or six coats of 1-2 lb cut. Don't worry about drips, runs, sags, or brush strokes, but then don't slop it on either.
Let it cure for at least four days.
Then 320 grit paper, maybe thirty seconds per square foot. 3M sandblaster paper and Norton 3X are better than most as they resists clogging with shellac dust very well.
Then 400 grit sandblaster or Norton for thirty seconds per square foot. Then 600 grit wet-dry then 800 grit wet-dry for a minute or so per sq.ft. with each grit. I start off dry then wash the paper and shift to wet as the paper clogs. I only get three or four sq. ft. of project done per sheet of wet-dry due to clogging and wear. Not cheap.
Then DuPont auto rubbing compound, followed by DuPont auto polishing compound then Meguires (sp?) swirl remover, one to two minutes per sq. ft each.
Lots of work if the piece is big.
I'm not a high gloss fan on most stuff, especially bigger pieces. I usually go 320 grit paper then 0000 steel wool rubbed HARD and dry for about 30 sec per foot then a minute per foot rubbed softly, and call me done. I love a baby butt smooth satin finish.
Chris
Edited 8/31/2008 10:37 pm ET by fishnskiguy
You should have rubbed it out with rottenstone and a felt block, waxed it, and moved on. People have been doing it that way for a long, long time.
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