" " wisno wood furniture finishing: Strip off the waterbased paint

Monday, August 27, 2012

Strip off the waterbased paint


Strip off old finish could be tough job, but it is needed when we want to update our old finishing with a new looked and color. The product must be clean and free from the old finish as an unfinished surface if we want to apply new finishing process (with new finishing process and material). We already post an article about strip off the old finish at our previous article:  How to strip off the old finish. In this article we want to share about how to strip off the waterbased finishing layer at the wood finishing. Waterbased finishing material includes the waterbased stain, waterbased coating, waterbased paint, latex paint or wall paint are quite much used in the furniture industry. They are can be used or in combination in the wood furniture finishing. The full waterbased finishing system is used to make the safe and environmentally friendly finishing system. While the waterbased paint, latex paint or wall paint also much used in combination with solvent base coating to make some special finish.
Although waterbased material uses water as solvent, but when it is dry it will cured, hard and won’t be resolved with water anymore. We need a proper solvent to solve and break the paint layer. More over the waterbased paint is usually thick and hard; it has to be completely wetted to get removed easily.  

Here is the process of strip of the waterbased finishing layer:

Dampen rag (or sponge) with washing thinner and put them at the coating surface, let the thinner soak and wet the finishing layer. It needs some minutes to let the thinner to wet, penetrate and break the finishing layer. The thinner used has to be the made of the solvents with high solvability to the paint. Acetone or MEK are the good solvents to be used, they are strong to solve the paint or coating. But they both have fast evaporation rate that could be too fast for the striping process.  We can add toluene, and (or) alcohol to the thinner mix to let it slowly dry.
The wet finishing layer will be broken, contracted and chipped off. Use a knife to scrape a layer finishing that is already damaged. Do the scrapping carefully since it may cause the scratch to the wood surface. Use the plastic knife to minimize the risk of scratching. Continue the surface cleaning with dampened rag; a scotch brite also can be used to rub the rest of the paint.  Although it has been detached from the wood surface, the waterbased film layer will not perfectly be dissolved. The waterbased coating particles may be left inside in the pores and grain of wood. We can use wire brush to clean the particles inside the wood pores and grains.
If there was wood stain at the finishing, then there may be some color at the wood. The stain is absorbed and will change color of the wood and cannot be cleaned with thinner. We can go ahead to apply the new finishing process at this condition as long as the new finishing color can be made based at the wood color.  But if the new finishing color is lighter the wood color now, then we have to re sand the wood surface. Use the # 180 sandpaper to sand the wood surface evenly. Make sure we got the smooth and even wood surface before start to do the refinishing process. 

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