I have a finishing problem. I am refinishing a set of chairs that had been previously refinished. After staining with an oil based stain I tried to finish with a water based lacquer something have never had problems with in the past.. The finish became soft and could be scraped off with my finger nai. Thinking it might be a problem with an old stain I redid them with a fresh stain and then left them for a week before trying to put a new finish on although not in all areas. I’ve tried shellac as a barrier but it doesn’t seem to stick. I also did a test with the original stain finishing over it after only half an hour drying to see if it would replicate my original prblem. It seemed to finish fine. I’m thinking there is something remaining from the previous stripping that is attacking the finish. I’ve seen similiar problems and invariably the people will tell me the piece had just been stripped. Am I right and how can I get these chairs done.
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Replies
More questions than answers.
You say the chairs were stripped? How? By whom? Using what chemicals?
I'd be tempted to strip them again, with stuff ranging from Mineral Spirits on the low end, and Methelene Chloride on the high end. I don't understand why Shellac won't stick; it sticks to everything.
Try some test stripping and let us know what happens.
Boris
"Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1934
Thanks for your reply. I can't really afford to strip them again I've already stripped them twice the first time by scraping and sanding the second with a semi-paste stripper containing the chemical you mentioned, after which I wiped it down with mineral spirits to remove the residue. I have no idea what the original finisher did but I am assuming they were tank stripped without properly neutralizing the chemicals. I was hoping someone would know of a way of either to neutralize or isolate the base. When the shellac came back off I kind of knew I was in trouble.
I was also hoping someone had had a similiar experience since like I said in the original posting I've seen similiar problems that seem to be tied to this kind of stripping.
Methelene Chloride is neutralized with water. It will raise the grain, but thats what is used, not mineral spirits.
I would also try Naptha which is like mineral spirits but is much better at cleaning that paint thinner.
I might try alcohol as well.
All these are cheap and easy and certainly worth a try on a small area. Total investment: about $10.
Regards,
Boris
"Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1934
kstrick,
You wrote that you cannot really afford to strip them again, but I think you cannot afford not to. It looks to me like they will be a total write off otherwise. Whatever is wrong is not going to go away by itself--especially if it is the bottom layer.
Alan
Well, it is either a residue from the stripper or the oil based stain.
Semi-paste methylene chloride strippers all contain wax, and I have never, ever had trouble removing it by giving the piece a light sanding, followed by a thorough wash/rub down with mineral spirits and steel wool. What brand was the stripper?
If you have done all that, then the culprit must be the oil based stain. What brand is it? How was it applied?
Also, I assume the barrier coat was a dewaxed shellac, right?
Originally I did not use stripper except on one area and I did wash it down with mineral spirits as recommended on the can. On one of them I also washed it down with TSP (also recommended) followed by water.The rest was scraped and sanded. The finish did come off very easily and seemed very brittle. The piece had been stripped and refinished with what I don't know. When the problem first occured I thought it was the stain so started over with fresh leaving extra drying time with the same results. The problem is not the stain since I did a test with the original stain pushing it well past recommended use allowing no more than half an hour and finishing over it with water based poly without a problem. The shellac was out of the can although I don't stir and try to take it straight off the top. I didn't use shellac the first time this occured.
It does seem like a wax problem although I don't know how that is possible since it was originally taken down to bare wood.
What do you mean when you say "I don't stir"? If you open a can, and there is a layer of oil or something floating on top, is that what you used without mixing all of the compontent parts together.
Did you read the label, is that what it said to do?
He's talking about shellac, not the stain.
Well, if he is talking about the shellac and didn't stir it then he has basically "shellacked" his chair with alcohol. It needs to be stirred, of course.
I would take some steel wool with stripper (it might not even need to be a very strong one) and wipe the chairs down firmly. Then I'd take a LOT of mineral spirits and keep rubbing them until nothing else came off. At that point I don't know what condition the stain will be in but stain if necessary. Let dry and then wipe on a varnish finish. Or put on a shellac sealer coat and proceed.Gretchen
Sorry, but you're wrong about the shellac; the standard way to "dewax " regular, conventional shellac is to let it sit until all the solids (waxes) accumulate on the bottom of the container -- then decant the liquid on top.
If you have a can of shellac that has been sitting for a few days, you can dip your brush in the top portion (as the poster did), and brush on a "dewaxed " shellac.
Edit to add: I concur with your stripping/staining advice.
Edited 7/9/2004 8:59 am ET by nikkiwood
First, thank you for coming to my defense, I don't know why people assume you are ignorant when you ask a question. I didn't take your advice completely but I did rub down the chairs lightly with mineral spirits. I also tried something else that is using varnish to isolate the finish since shellac wasn't working. Your original reply made me think of another possible cause of this problem and that is whoever refinished these before didn't strip them but just finished over them directly leaving whatever was built up from before. I will never know. The varnish is working I coated one chair yesterday with varnish sanding sealer and today just got through rubbing it down. The surface was hard and dry with no problems with the finish pulling away. This may not have a precedent in finishing but in art it is more common to use varnish especially with uneven drying or a too dry surface. I plan to finish this with a sprayed on water based lacquer (Enduro). I've done this before but I am doing a test in this case.
To everyone who took the time to reply I would like to say thank you. Only one correction to Boris Yeltsin, water is not a neutralizer being a hopefully inert substance. The goal in using water is to wash off the stripper although you may also be driving it into the wood.
Thanks again
Kevin
The brand of Methylene Chloride I use specifically states to use water to neutralize and remove it. This MC is a home brew out of a Company in Glendale California that sells it in 5 gal cans, both liquid and paste. It is really nasty stuff, but really works well.
We heat strip flat surfaces first with guns and putty knives, then move on to several coats of MC.
I am a remodler and have used this brand and this technique for over 15 years, and have stripped probably 50 homes with an aggregate square footage of 100,000 square feet. This technique works for me and is recommended by the manufacturer of the product.
Regards,
Boris
"Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1934
Boris,
After reading more about it I agree it is nasty stuff and I stand by what I said water will not neutralize a chemical only dilute it. What they are having you do it dilute it to the point it no longer can act on the surface and hopefully carry it away. In reading it is stated exposure is taken care of with soap and water. Soap would act as a neutralizer as would soda. You still have to rinse that off.
In using mineral spirits I was also following the manufacturers recommendation.
I gather from your methods you are fairly conservative in your methods; heat stripping before going on to more aggressive means, but there seems to be alot of misuse and overuse of these chemicals out there. I was hoping I wasn't alone in thinking that. I will never know for sure if that was the culprit but it is my number one suspect.
Kevin
I assume that is a base as opposed to an acid, and one would need a chemical with a slightly acidic composure to neutralize it. Dunno. I am not a chemist.Regards,
Boris
"Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1934
Boris--
I think your advice was really misleading. You took a product that is probably only available to people in the trade, and then lumped it in with all the weaker stuff commonly sold over the counter. And then you told this poor guy to wash it down with water, which is contrary to every widely available stripper I know about.
Water used as a wash can do a lot of damage in a hurry -- if you don't know what you're doing.
Finishing (and stripping) can be an enormously complicated undertaking for one without a lot of experience. So unless your advice is very generic, I think it is always better to name brands, and explain what product your recommended technique is tied to.
You know, I pulled off a gallon of Jasco Stripper off a shelf, which is popular and common consumer stripper, and the label recommends water to neutralize the stuff. The stuff is water based, as opposed to oil based, so you will get a huge amount of grain raising when using the stuff, so sponging some water over the wood you've just stripped is not going to cause any more damage than you've done in laying water based stripper over the wood for 6 hours.
That being said, one of my guys that does the stripping likes to use lacquer thinner to rinse it off. So go figure. There is no right or wrong here Nikki, just different ways of doing things. If you think I am wrong, then pick up some Jasco and see for yourself.
Regards,
Boris
"Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1934
. The material itself is a solvent and probably can be thinned in its pure form by a variety of thinners. Maybe maybe not. You are right that water is generally listed as the thinner. Nikkiwood is correct that you want to avoid to much wetting on a piece of furniture and not just because of grain raising, your liable to regluing the entire piece. Also the most common variety of strippers are a mix of various solvents in a some kind of base.
One question to you and Nikkiwood. Most solvents will evaporate fully leaving a neglible residue. Is this the case with this material? If it is than neutralizing would be unnecessary.
By the way I am not an amateur woodworker. I have been carving and making furniture for over 20 years. Professionally for the last eight.
The chairs are complete using the varnish to seal them. Lacquer might also have worked but this seemed less likely to become brittle over time.
Kevin
I'm not a chemist, so I don't know, but I wanna get that nasty stuff off the wood. It raises the grain (it has to be water based, if it does that right?) and is nasty to touch, and obviously would play h e l l on any finish applied over it. I want it off and in the trash.
When I use the stuff on homes (I have never used it on furniture) we go over it with coarse steel wool until we hit the wood, then maybe go down to "00" to finish it off. The steel wool does a good job of removing the stuff, as it gets caught in the wool. We then toss the steel wool. A quick swipe with a sponge and dry the area with a terry towel.
Repeat as necessary until the area is 90% stripped. Once we are down to bare wood, we switch to 100 grit sand paper. Then 150. If there are any spots left, we go over it with more Methelene Chloride perhaps wrap it in plastic and let it sit for 4 hours. It loses its bite after 4 hours, and will no good, and will leave the finish on as opposed to taking it off after than. Then hit it with steel wool, or a steel putty knife, which we grind down (We have a bunch, of various shapes) to remove the last little nubs of paint. Then more sandpaper and etc.
I have may have to follow up with heat guns, too, you never can tell what will get the last bit of paint off.
We have about 8-10 window box type fans and maintain a very positive flow of air in the home on one side and out the home on the other side. We take ventilation fairly serious with stuff. We don't use masks, but each room has at least 2, and as many as 4 fans blowing that nasty stuff outathere. Thick rubber gloves are a necessity.
This is the way we do it.
Regards,
Boris
"Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1934
It's the water that's raising the grain not the methelene chloride. What I bought either probably has a smaller amount along with other things, acetone, tuluene, etc. As you say after four hours it loses its bite which probably means it has totally evaporated. Obviously you wouldn't leave it or your spinning your wheels.
After going through this discussion it seems to me what you are using would cause less problems than using something containing wax. I also prefer using one solvent at a time appropriate to the finish. You say you also use semi paste stripper. What does it have in it that makes it thicker?
I try to avoid stripping furniture, good furniture should never need it,but sometimes good furniture falls in with the wrong crowd and needs to be saved. Done correctly your method sounds safer with less residual affects. Small amounts of water won't cause any problems that a light sanding won't take care of. If the product evaporates fully as you say washing it down with water it down wouldn't be necesary. I'm talking about furniture after the disolved finish by other means.
Thanks
Kevin
I am a chemist, though I'm less experienced at woodworking than most here. For those who are wondering... Methylene chloride itself is a liquid that evaporates very quickly, leaving no residue. It can dissolve more different kinds of things than can mineral spirits or alcohol (that's why it's so effective as a component of strippers) but it does not mix with water. It should not raise grain by itself. However, many times what you want to clean off has stuff in it that will dissolve in water, and stuff that will dissolve in methylene chloride, so you want both present since a little of one thing can act as a barrier and prevent the other from working well. So the semi-paste stripper is probably water and methylene chloride with a surfactant added. Without a surfactant, they would be like an oil and vinegar salad dressing -- two layers. With the surfactant, they are like mayonaise: a dispersion of small droplets of one phase in the other. It's the water that raises the grain, and cleaning up after the stripper may be described as "neutralization" on the can, but it just means cleaning off the leftover surfactant. Methylene chloride is not an acid or a base, but it evaporates so fast you wind up breathing a lot of it if you're not careful. The water in the dispersion can cover the methylene chloride surface, slowing down its evaporation.
Alan,
What would the surfactant be since that is liable to be the cause of the original problem? Normally it would be a soap or wax; right? What would be the safest and most effective way to remove it if such is present already?
Thanks,
Kevin
No soap or wax in methylene chloride strippers. Methylene chloride, mineral spirits, ethanol and methanol. The mixture is slightly soluble in water. 10 or 15%. Probably no surfactants. Thickening agent may be methylcellulose or hydroxypropyl cellulose. Something like that in very small quantity. a tenth of a percent maybe. Doesn't need much. Methylene chloride will remove wax, oil and most silicones. Scrub afterwards with water or spirits to remove gunk. No neutralizing necessary. Nothing to neutralize since its a solvent rather than an acid or base. The thickening agents are nontoxic and water or alcohol soluble. Less than a percent of anything except solvents in the mixture.
While we're waiting for Alan (the chemist) to weigh in, could you tell us what leads you to conclude there is no wax (or a wax like substance) in semi-paste strippers?
Look up the MSDS for a couple strippers. They all show 99+ percent solvents. The people who make strippers understand that they're used for refinishing furniture. They don't put in stuff that would interfere with refinishing. I know of no products that use wax as a thickening agent. Cellulose compounds, collagen (gelatine or hide glue) , seaweed derrivitaves, proteins, starches and silica or silicates. Those are thickeners.
While the formulations of most strippers are proprietary, I suspect that the thickening agent is Klucel hydroxypropylcellulose, methyl cellulose or less likely, a silicate. A fraction of a percent turns alcohol into solid jello (sterno). Silicates are used to thicken gasoline into napalm. All are also used as thickening agents for gel stains and varnishes. I don't have any of that stripper handy. Too toxic for me. But, if you have some put it in a pan and let it evaporate. I'll bet that you have an almost invisible amount of a fluffy white powder left over. Add a little water. If it turns to instant jello, its a cellulose compound. No, I'm not a chemist. But, I am an engineer and physicist and have spent a good 30 years working with coatings.
Re: wax in semi-paste strippers.
Here's what Bob Flexner has to say in UNDERSTANDING WOOD FINISHING:
" The solvents in [methylene chloride] strippers ..... evaporate rapidly, so paraffin wax is almost always added to retard evaporation." (page 290).
Flexner's main gripe about finishing products has always been that the makers disguise or obfuscate the ingredients of their products. His book is still considered by most to be the definitive treatment of finishing. And he certainly does a masterful job in demystifying what these concoctions consist of.
I'm afraid your statement that manufacturers of strippers "... don't put in stuff that would interfere with refinishing" -- is simply not accurate.
If one does not adequately clean the surface of these stripper residues, either by sanding and/or scrubbing with solvent, it is just about inevitable that the final finish will not adhere properly.
I don't know what brand he uses. The last I used was Kleenstrip. It has no wax. Paraffin does not wash off easily with solvents. Just gets diluted and driven into the wood. You'd have to wash it many times. I used strippers often enough before the toxicity was widely known. Lots of different brands. Never once had a problem with the finish not sticking. I never washed with solvent, just plain water.
I'd agree that it would be a poor idea to add something to a stripper that would mess up a finish. A wax sounds unlikely, but the word is not very specific, and there are a few things that might be called waxes that could work. Polyethylene glycol (PEG) is also known as carbowax, and is used to stabilize wood by replacing water. It's very different from paraffin wax, or other waxes. Bob: the reason I believe the stripper under discussion has water and surfactant in it, and not just a jelling agent, is that it raised the grain of the wood. A hydroxypropylcellulose would probably work well as both thickener and surfactant. The key point though, is that wiping with a rag damp with water ought to remove most of it, whatever it is. That may just be a roundabout way of saying that the instructions on the can might be worth following.
With that mix of solvents, its miscible to about 10 or 15% with water. A cheap way to cut the cost a little and possibly slow evaporation as well. Who knows, it may even work better that way. I don't doubt that some companies would do that or maybe even add wax. Seems to me like a real quick way to lose customers. Although, a lot of the major brands of finishing supplies they sell at home centers are such garbage that I wonder how they ever get a second sale.
What I said above was based on my evaluation of the likely composition of strippers, not on measurement. Here's a link to some real data: http://aic.stanford.edu/jaic/articles/jaic32-01-005_2.html
One of the things they mention is that almost all strippers contain surfactants that are not on the MSDS because they are present in low quantity. The substances they list as surfactants used are common detergents. They mention that emulsion cleaners (as I am suggesting might be present) are used in cases where strongly alkaline conditions of carbonates, silicates, or TSP can't be tolerated.
Apparently, paraffin wax is used as a thickener in methylene chloride based strippers. I guess it's supposed to be scraped off with the old paint, and the little bit left must be thought not to be a problem. You'd need a solvent to get it off the surface, but that's likely to make it soak in deeper. Water will serve to remove the surfactant though, and acid or base. While paraffin wax sounds like exactly what you don't want on wood before you finish it, I suspect that traces of it usually don't make a lot of difference. Silicone oil and waxes are to be avoided because a little bit can make a bigger difference.
To get back the question that started this thread, it's hard to tell what prevented the water-based poly from hardening. Wax might make it not stick, but shouldn't prevent hardening. But since the original poster did the experiment to check the stain and it didn't cause a problem, that leaves the stripper, and anything previous. Water-based poly looks cloudy before it dries because it is really stuff that does not dissolve in water, dispersed as tiny droplets in water, with an ionic surfactant that prevents the droplets from sticking together. When the water dries, these droplets wind up next to one another, and the finish curing depends on the long molecules of adjacent droplets getting tangled with one another. When that happens, except for the little bit of surfactant, the finish should be pretty much the same as it would have been with a standard poly, where the molecules were dissolved in a solvent, and became tangled as the solvent evaporated. I will take a wild guess and say that maybe there was a lot of surfactant left from the stripper, which would not affect an oil-based varnish, but did combine with that in the water-based stuff, (and perhaps water -- high humidity would be a problem) to slow down the coalescing of the poly droplets. If I recall correctly, your finish did harden eventually. If this view is correct, it should be fine now.
Re: residue in stripper.
Ordinarily, I think you are correct; the chemicals in most solvents will evaporate , leaving a negligible residue.
But with semi-paste strippers, they use some sort of wax to give the stripper body so it won't drip and evaporate more slowly. So it is not the chemicals that are a problem, but the wax. This must be removed either by sanding, or scrubbing with a solvent -- paint thinner works and is less innocuous than lacquer thinner, which will also do the job.
Unless there is some really compelling reason to do so, I would never use water to wash down, even if suggested by the directions; it will obviously raise the grain, but it can also weaken glue joints in furniture pieces, and sometimes even cause the joints to fail.
Ok, I'll take a shot....The guy who refinished before you had a fisheye problem,and to solve it he used fisheye preventer in his finish...Fisheye preventer is pure silcone that you add to the finish and viola,no fisheyes.Since the finish has lots of silcone in it,and even though you removed it is still in the grain/pores of the wood. thus your problem???
Although I agree with Boris that shellac (de waxed) will stick to anything,and hold any finish, not sure why that didnt stick.. Just a thought...
shoot it all with a mist coat of nitro lac. then a full coat.
after that anything ya want.
Spheramid Enterprises Architectural Woodworks
Repairs, Remodeling, Restorations.
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