Hi! An old cupboard made on softwood was given to me. It is coloured with oil paint. My aim is to remove this painting. It was told to me that caustic soda is a possibility. Has anyone experience with caustic soda? Or does anyone knows other ways? Any idea on this is very appreciated. Best regards, Chablisa
chablisa asks:
Does caustic soda=lye? I think it does. Best avoided if possible. Modern paint removers do a decent job, with less hazard. I've always had good luck with ZAR Paint & Varnish Remover.
Charlie Self "Did you know that the White House drug test is multiple choice?" Rush Limbaugh
Pros use a dip in caustic, which just isn't practical for single use. The strippers are formulated to stick to the piece so it doesn't have to be immersed. Not all strippers work against all paints, though the nastiest, methylene chloride, seems the most effective.
Lots of caution even with the "environmentally friendly" types advised. Goggles, gloves, and disposable clothes.
|Hi! |An old cupboard made on softwood was given to me. It is coloured with |oil paint. My aim is to remove this painting. It was told to me that |caustic soda is a possibility. Has anyone experience with caustic |soda? Or does anyone knows other ways? Any idea on this is very |appreciated. |Best regards, |Chablisa
Caustic soda---lye---Sodium Hydroxide will strip paint. In my youth, I worked in an automotive machine shop and we used a heated tank full of the stuff to remove the crud from cast iron engine blocks, heads, etc. In my later life in the missile business we used brief immersion to clean aluminum parts before chemically treating them.
I believe some commercial paint stripping operations use something similar.
The problem is that it can damage the wood to some extent and should be neutralization with weak acid afterwards. All of this water will raise the grain of the wood and glue joints don't much care for this insult either.
Some commercially available strippers are lye-based (no pun intended) and include thickeners to make them stay on the work surface while they do their thing. I've heard of homemade versions of these using things like cornstarch for thickeners.
If your project is to be repainted, doesn't have glue joints and you have a method for safely applying this stuff, than it might be appropriate. Otherwise a commercial stripper, also handled with the appropriate cautions, is your best bet.
I have some experience here and I wil provide what I have. I have and have been working on an old house for some years now so paint stripping is one of life's constants for me. Couple of observations I have made (personal opinions and experience only so please keep the flame-throwers in check)
1) Chemical strippers are frought with issues. The best chemical stripper I have used is Peel-Away 1. It strips paint like nobody's business but the watch word here is MESSY. The process is that you smear it on, put a "special" paper on it, wait a while, peel off the paper and the paint. You have to "neutralize it" after you are done and you basically need to repaint as it stains the wood. Peel Away 7 is supposed to not require neutrilization and not stain wood but I have never used it. The company says that it is perfectly safe but you can hear it working. For my money, if I can hear a chemical working then I am giving it it's distance and applying all sorts of safety measures regardless of what the manufacturer tells me. There are others, that are of varying degrees of effectiveness, mess, hazard. MC-based ones seem really dangerous. Peel Away 6 doesn't work worth a crap in my opinion. 2) Heat gun. If you are SURE the paint is oil-based and NOT lead-based (this goes for all layers of paint) then a heat gun might just be your best bet (assuming you are repainting). You just need a good scraper, lots of time, and lots of patience. Watch for fire though, especially if the cabinet is not free-standing and there is a substrate behind it. 3) Sanding / mechanical removal. This is tough-love and I don't recommend it for things with any appreciable amount of surface area. 4) There is a product call the SilentPaintRemover that is quite good. I have one and am quite familiar with it's operation and can answer questions if you have them. Web site isThis topic is discussed to death in old house forums, you might also want to try there for more information.
The process may well damage the piece what with having to neutralize with some acid. FWIW, we used to dehorn calves using caustic soda. Quite common practice but nowadays with all the polled varities not necessary.
Please don't let the kiddies do this. Their idea of brief may differ.
Launched many a hydrogen-filled balloon as a kid after generating same with NaOH and Aluminum.
In my later life in the missile business we used brief immersion
Sorry. I missed the OP.
NaOH (Caustic Soda, Lye ..) is the direct oppposite of a strong acid. SO, imagine how you'd do if working with a strong acid like Sulphuric [sulfuric] or Hydrochloric. Chemicals such as this euire extrreme caution; well, at least not an entire lack of caution. I.E. rubber gloves, goggles even an apron if protecting clothes.
To use on softwood is not a good idea. I easily stripped old brown varnish from the woodwork of my older home. I removed the wood, and took it outside. There, I brushed vigorously with a stubby-bristled, cut-down old paintbrush using TSP (Tri Sodium Phosphate.) It removed the varnish easily, but paint would be more stubborn, just requiring a bit more patience. When scrubbed to my satisfaction, I simply hosed off the gunk. All the mess was outside, which is where you should do your work.
You said "an old cupboard", so if self-standing, take it outside. If kitchen cupboards, it is still worth removing them, finishing, then replacing to avoid all the other work.
Bill.
This is an excellent summation. (I'm a fellow old-house owner, and have also suffered through my share of this!)
It's probably worth adding that lead paint would also be an issue with sanding. You don't want to kick up any lead dust. I seem to recall that heat guns were actually somewhat safer in this regard, compared to sanding. There may be more recent research on this, though. Either way, it's worth paying attention to possible lead content. If the piece was painted before 1950 or thereabouts, there's a good possibility that one or more coats contained lead.
I have used caustic soda quite a bit as a paint stripper, it seems to give mixed results, but always works better when hot.
It is nasty stuff, though and you must wear gloves and goggles. It also is a bit rough on the wood, but it cleans up well enough.
Do it well outdoors, in an area you can hose down the whole mess when done.
I have been meaning to do a small trial mixing caustic soda with wallpaper paste to make a "caustic gell" Most of the paint strippers are a gell, so as to hold the stripper against the wood for a longer period.
Barry Lennox
The cornstarch gels it nicely. Dunno about paint, but it's pretty much worthless as a stripper on Helmsman exterior polyurethane.
If you are SURE the paint is oil-based and NOT
(and still more...)
Not a flame, but a mere correction: lead was (and is still, just not for residential purposes) used as a pigment in paint. It is not a "base". The base would be some kind of oil, an alkyd (think synthetic oil), or, in the case of latex paints, water. The "base" is the carrier or solvent in which the other ingredients are suspended, dissolved or otherwise distributed. The "base" evaporates and leaves behind the pigments, bonding agents, and a multitude of other things that make the paint flow, stick, resist the sun and (acid) rain, etc.
Lead is wonderful as a pigment because it stays put and is tough as metal (this last is kinda obvious), but it sure plays havoc with living systems (nerves, blood, bones, kidneys...it has an affinity for red blood cells, and thinks nothing of taking the place of iron in hemoglobin) so we don't use it in homes any longer (thank you, gov't regulation). However, it's still used in industrial paints, highway paint, etc.
The point of all this is that if the cabinet in question was painted before 1980 (and even later--how many cans of paint are in your basement and how long have they been there?), the paint probably has lead in it. In addition to using appropriate precautions for whatever method you use to strip it (chemical, mechanical) be aware of the potential lead poisoning hazard. Anything you do to take the old paint off can pollute the area in which you work so be careful, keep the kids away, wear proper clothing and gear, etc. Lead poisoning is no joke.
The EPA has information about safe treatment of lead bearing paint which you can probably find on their website
Good luck, and strip safely.
Dan
DO NOT (shout intended as hazard eminent) EVER use a heat gun, especially one with an open flame. The heat can release the lead as a toxic, readily inhaled vapor. The safest methods for removal will be mechanical--wet sanding and scraping, with the significant word being "wet". Lead dust is less easily inhaled because it is too heavy to stay suspended in the air (it is lead, after all) unless there is a lot of dust and the air constantly disturbed, as in heavy demolition. Chemical stripping would be a distant (because of compounded toxicities) second choice. Heat guns should never be an option.
Lead bearing paint was manufactured for the U.S. consumer market until
1978. Given that inventories probably stayed on the shelves for a while after that, it is wise to consider anything painted before 1980 to have at least one coat of lead bearing paint; given how long some cans of paint survive neglected in basements, it might be wiser to add a even more years.To your health, Dan
It also depends on the fineness of the dust, which will remain suspended for some time. It will also coat other items. I.E. Wear a mask, even if wetted.
One common key throughout all of this is to take outside if feasible.
Bill.
Methylene chloride - Lye. Drop of lye in your eye and you need a new cornea. OTOH, it doesn't insinuate itself into your blood stream and lead to cancer, liver disease and the other nice things associated with meth chloride. Much kinder to the environment and used by our grandmothers without fatal result for a long time making soap. I think I saw a recipe somewhere using corn starch with lye to make a paste remover which clings to the wood long enough for it to do the job. (Don't hold me to this, it was some common kitchen item used as a thickener.) IIRC, meth chloride has a particularly hard time with milk paint. I've applied a fair amount of it (milk paint) but haven't had to strip any yet.
Bob G.
George wrote:
Since when? Am I reading you wrong?
Bill.
= lie.
Lye is sodium hydroxide, not methylene chloride. Whatever gave you the idea that it was methylene chloride?
Looks like an either/or proposition to me, based on the verbiage.
You might have read that wrong.
Use caustic soda as a last resort. It is pretty vicious stuff and can damage the wood if you don't know what you are doing.
You don't say how large the cupboard is but I will assume that it is small enough that you can handle and turn it on a large suitable surface.
You don't indicate how old it is. I realize you have said "oil paint" but I do not know how you determined this. If it is very old, you may have milk paint. There are specialized removers for this that are safer than caustic. If it is indeed oil paint, there may be lead in it so don't go for sanding or a heat gun. All but the milk paint can be removed with standard methylene chloride containing strippers although there are removers made specifically for paint. BIX makes one that is a powder you mix with water.
The best thing you can do is to buy a small quantity of a methylene chloride based stripper and try it out over a small area. If it works, you have just saved yourself quite a bit of time spent on specialized safety precautions.
One of the most difficult aspects of stripping paint is if the paint was applied to the raw wood. It is MUCH easier to strip paint from something that had a clear coat finish and was then painted over. Paint tends to lodge in all the pores, splits, and cracks so well that a fair amount of time spent in getting it out.
Good Luck.
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