There are many reasons why we want to remove the old finish coat from doors, furniture or other objects: the paint coat is cracked or skipped, the current colour is too dark and we want a lighter one, the wood is painted and we want it varnished to show the grain, we don't know what the original paint was and we don't want to risk the new coat peeling, etc. One of the preferred methods of removing old coats is stripping. Why it is a preferred method, how stripping is done, what materials are used and how the wood is prepared for repainting is explained below.
When stripping is the recommended method to remove paint from the wood surface
According to the DEX, pickling is the removal of grease or oxides from metals. The term has, however, also been adopted for cleaning wood, and the solution used for this purpose is called paint stripper. Pickling solution names in Englishpaint removeror in Italianpaint stripper,are more accurate because they refer strictly to paint removal. But the market has adopted the term paint stripper and under this name you will find solutions in specialist shops.
We choose pickling especially when the shape of the object or the carvings present on the surface of the wood make it removal of old paint layers by other methods to be very difficult. The most suitable method for such surfaces would be sandblasting with softer abrasive materials (baking soda, shredded walnut shells, corn cob husks), but it is harder to find wood sanding specialists and, besides, the method is expensive.
Stripping does not require high costs or special equipment or skills. Patience is needed because it is not enough to apply a coat of paint stripper and the problem is solved. Most of the time the procedure needs to be repeated 2-3 times to remove the paint completely. After the paint stripper has been applied, the paint will soften and must be removed with a scraper. On difficult surfaces thin tools should be used and often the surface also needs to be washed with thinner to clean the wood thoroughly. I did this when I cleaned the doors of the Pitar Moș church. Find heredetailed step-by-step information.
Are there more than one kind of paint stripper or just different brands?
Paint strippers are solutions that attack the paint, making it much easier to remove. They are either very aggressive solvents or acids or bases that attack the bonds inside the resin, destroying it. Restrictions on the use of some products now considered hazardous to health have made paint strippers less and less aggressive. In a way, I agree with those who say that "in their day", paint strippers were better. Yes, they were much more aggressive and very rarely needed to be repeated, but they were also much more dangerous.
The three main types of paint strippers
- Aggressive solvent mixtures
- Pickling solutions for natural oils or alkyd paints and varnishes
- Universal waterborne pickling solutions
Solvents are used more in factories because their strong smell is hard to bear. In factories there are high-performance exhaust systems that remove solvent vapours, but even so it is hard to work without a mask and protective equipment.
Paint strippers for alkyd oils and paints are caustic soda-based. They attack the inner bonds in the resin turning the paint, oil or varnish into a liquid that is washed away with water. The problem in this case may be the water used for washing. On old and sensitive items, too much water may not do any good. But if the wood is sound, the method is preferable because it removes old coatings simply and well.
Universal water-based paint strippers are the most used. They are generally in gel form because they take time to work. If you have a choice between a liquid stripper and a gel stripper, choose the gel, it's much more effective. The differences between the different brands are due to the concentration of the active substance, hence the greater or lesser effectiveness of the respective products. Only by testing them can you determine which is better. Until recently I thought that Decanol from Policolor was a good paint stripper. I even recommended it many times. I worked with it 8-10 years ago and it was very effective. Two months ago, when I worked on the doors of the Pitar Moș church, I tested three paint strippers: Decanol, Dekapant gel Kober and Supralux Extra Strong Universal Paint Stripper. Of all of them, Decanol was the weakest, Supralux paint stripper was far more effective.
Paint stripper application and removal
The paint stripper is applied with a brush, in a not very thin layer and left for the time recommended by the manufacturer, usually between 20 and 30 minutes. During this time the paint layer softens and sometimes wrinkles a little. Paint stripper does not work well at very low temperatures. At high temperatures drying should be avoided. A well wrung wet cotton cloth placed over the top prevents drying and can increase the effect on the paint layer.
The soaked layer is removed with a scraper, narrow chisel or wire brush with thick brushes and bonnets. Brushing is effective when the surface has intricately patterned carvings. It is not simple and takes a lot of patience. Soaked varnish often clings to the brush and must be left in thinner to clean thoroughly. If the surfaces are straight, cleaning is easier and quicker. Very rarely does the surface clean completely in one operation, but the hardest is the first time. Over time the paint becomes softer and easier to remove.
After complete removal of the paint layer, the surface sometimes remains tacky and should be wiped off with a thinner recommended by the paint stripper manufacturer. If there is no such recommendation, use a wash thinner or universal thinner. If wiping with a cloth is not sufficient, apply the thinner with a brush and then wipe with a clean cloth.
Preparing wood for repainting
Before repainting it is recommended to sand the wood as in the case of white grinding. The old finish has entered the pores of the wood and to ensure even staining and adhesion of the coats to follow, the pores must be opened. This is the purpose of sanding. If staining is attempted without sanding, the wood may not absorb enough and light stains may appear.
Sand with 150-grit sandpaper, even 180 or 220 if the wood is sanded or sanded (plop). Then dust with a cloth. Dust from sanding spoils the appearance and reduces the adhesion of varnish or paint layers.
I hope you find the information interesting and useful. We always welcome additions. And if you have any questions or queries, please leave them in the space below. I'm sure I'll answer them.
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Thanks for the advice, I really needed this information.
Very useful information. Thank you!
I manually cleaned the door by removing the old paint from the door frame, but only that which was peeling easily. I washed it and degreased it with thinner. Before applying the primer, do I have to sand where I removed the paint? I use Sticky brand oil based, universal paint enamel. Thanks!
The problem with the remaining paint is that if there is very little peeling this will become more pronounced over time and the peeling will not be prevented by the newly applied coat. Sanding helps you to see if the peeling has started and removes those bits of paint. Sanding also helps to increase the adhesion of the new coat of paint to the old one left in place.
On the other hand, washing and degreasing the surface would have caused the paint to peel off if it was already chipped. If this didn't happen it means it's well attached. And it does not appear from the product data sheet that the old surface should be sanded.
In conclusion, you don't have to sand if the remaining paint is well attached to the wood.
Hello, I greatly appreciate all the information received through your articles. I have from my parents some pieces of "communist" furniture, classic, from the 80's, brown, lacquered, glossy. I would try to change their appearance (even the shape in places) and I don't know if the lacquered surfaces can be painted directly, just with a simple sanding, or should be stripped with solvents and follow all the steps above. Thanks
Hello!
Thanks for your appreciation!
Lacquered surfaces can also be painted, but you need to ensure adhesion so that the new coat doesn't peel.
One possibility is to use Annie Sloan-type chalky paints. They're more expensive, but are made specifically to adhere to difficult surfaces. Surfaces don't need to be sanded, just degreased. Degreasing is done by washing with water and dishwashing detergent, after which the furniture is wiped with a soft cloth and left to soak. The first coat is applied thinly without diluting the paint. Brush until you feel the paint has set. After the first coat has dried, apply the second coat for full coverage. Finally the paint is fixed with wax or varnish (from the same company). The paint and varnish are water-based so there are no problems if you apply them at home. I leave below some links to articles you may find useful.
Another option is to use ordinary water-based or solvent-based paints. In this case it is mandatory to degrease and sand the surface so that the paint adheres. The advantage is that no wax or varnish is needed to fix the paint. Sanding, however, can be very difficult, especially on high-gloss surfaces. For this type of furniture, polyester varnish, which is very hard, is often used. It is possible that sanding can only be done mechanically, manual sanding is very difficult. To create adhesion sanding is done with 280 or 320 grit sandpaper.
I hope this has been useful.
Good luck!
https://revistadinlemn.ro/2018/01/23/vopsele-cretoase-annie-sloan-chalk-paint/
https://revistadinlemn.ro/2018/02/21/transformarea-mobilei-cu-vopsea-pe-baza-de-apa-annie-sloan-chalk-paint/
https://revistadinlemn.ro/2021/08/05/vreau-ca-aspectul-mobilierului-sa-fie-vechi-stil-shabby-chic-cum-sa-fac-transformarea/
https://revistadinlemn.ro/2021/03/04/vreau-sa-schimb-aspectul-mobilierului-ce-pot-sa-fac-fara-costuri-prea-mari-si-cu-efort-redus/
https://revistadinlemn.ro/2020/10/29/ce-trebuie-sa-stii-daca-vrei-sa-revopsesti-mobila-sau-usile-de-lemn/
Hello, thank you very much for the extremely useful article.
Before seeing the article :), I bought Supralux gel paint stripper, which I applied to a very old piece of furniture, with many carved areas, which over time has suffered repeated mistreatment with different types of paints, roughly applied in successive layers. I applied the paint stripper twice hoping that the thick layer of paint would somehow melt, but I can't manage to clean the soaked paint due to the intricate carvings, I tried with various brushes, with rough brushes, with thinner, but the paint that's soaked and hardened up in the end won't come off unless I try to scrape it off with a knife tip, which is impossible to do because of the intricate carvings (I think it would take me a month to clean it that way). I left the piece as it was until tomorrow, with the thought that maybe tomorrow it will come off a little easier.
From your article I understand that I should not have let the paint stripper dry. Can you kindly advise me what I should do tomorrow when the paint stripper has dried? Should I try to strip the paint with a brush, or should I apply a new coat of paint stripper?
The second question/prayer is about the intricate carvings and ornaments that are now full of "bleached" paint that won't come off. How do I get out of the mess in an honourable way? 🙂
Thank you kindly, in advance, for your reply.
Hello!
You need a wire brush to clean the carved areas. It is not easy and you will have to repeat the operation, i.e. reapply stripper, leave 20-30 min. and brush the area. After each brush cleaning, apply a universal thinner, with the brush, to the excess, then wipe off with a cloth.
You can try to remove the wrinkled and dry layer with the wire brush. If it has come loose enough pieces will jump out. If they don't come off, the adhesion is still good and you need to reapply the stripper. You can extend the time the paint stripper is working by putting a wet cloth over it. But don't leave it on too long because it sticks.
Carved areas are difficult to clean. For them, sandblasting is most effective. Cleaning is done with a strong jet of baking soda particles or dry ice. But the operation requires equipment, is more expensive and must be done by specialists.
I am leaving below a link to an article about the restoration of some carved church doors. There I used wire brush and thinner wash. I hope you find it helpful.
I also leave the links about sandblasting.
Good luck!
https://revistadinlemn.ro/2022/08/04/cum-am-refinisat-cu-lazura-precolorata-kreidezeit-usile-exterioare-din-lemn-de-stejar-ale-bisericii-pitar-mos/
https://revistadinlemn.ro/2021/09/16/lemnul-innegrit-de-vreme-sau-straturile-vechi-de-vopsea-se-pot-curata-prin-sablare-atentie-insa-la-riscuri/
https://revistadinlemn.ro/2022/11/17/sablarea-cu-gheata-carbonica-o-metoda-de-curatare-fara-reziduuri-a-lemnului-de-straturi-vechi-de-vopsea-sau-murdarie/
Hello,
Thanks for the article.
I would like to refurbish some doors and door frames which, unfortunately, have been painted with very thick, successive coats.
In some places there are cracks in the wood.
Can you tell me, please, what is the best method for removing the paint and getting to the wood for repairing the accessorizing?
Thank you.
Have a good evening,
Alex
Hello!
I think the easiest and with good results is with paint stripper. The coat being thick is very hard through sanding, and special sanding for wood I don't know if you have it handy.
I leave below an article about Borma Wachs paint strippers and how to use them. They are quite aggressive and you get clean surfaces.
In DIY stores you can find other brands, more or less aggressive. There's also an article about redoing some exterior church doors where I used various paint strippers.
After stripping, put putty the wood, sand well and then reapply varnish or paint.
Good luck!
https://revistadinlemn.ro/2024/05/31/indepartarea-straturilor-vechi-de-vopsea-ulei-si-ceara-de-pe-lemn-si-alte-suprafete-cu-produse-borma-wachs/
https://revistadinlemn.ro/2022/08/04/cum-am-refinisat-cu-lazura-precolorata-kreidezeit-usile-exterioare-din-lemn-de-stejar-ale-bisericii-pitar-mos/