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So-Called “Green” Paint Strippers

Jun 21, 2016 | Expert's Corner | 0 comments

There are an increasing number of so-called “green” paint strippers on the market with problems you need to be aware of. These strippers are easy to identify by their packaging, which is always in plastic containers. Traditional methylene-chloride and flammable-solvent strippers are always in metal cans.

The packaging tells you everything you need to know about the strength of the stripper. Strong solvents dissolve plastic. So the green strippers use weaker solvents.

These strippers are still very effective, however. If given enough time, they will liquefy or loosen the bond of almost all paints and finishes.

There are four things you need to be aware of when using one of the green strippers:

  1. Almost all brands claim they work much faster than they do. Two decades ago, when the first of these strippers came on the market, they quickly got the reputation for “not working.” They worked fine, but not within the amount of time claimed on the containers (usually 20-to-30 minutes). Right now I’m looking at a green stripper that claims to work in 5 minutes! It may take hours or overnight on some coatings, but given enough time, these strippers are usually effective.
  2. It’s actually the coating that’s being removed that plays the biggest role in determining the speed a stripper will work. For example, latex paint, shellac and lacquer dissolve rapidly with many solvents, so these coatings can be removed fairly quickly. But oil paint, oil-based varnish and polyurethane, some water-based finishes, and all high-performance finishes (which are being used increasingly in factories) resist the penetration of solvents. This is of course the benefit of these coatings: to hold up longer against being damaged. So more time is required to loosen these coatings from a surface.
  3. Many green strippers contain a lot of water. This may be promoted on the container because marketing people think it’s a good thing. But leaving water in extended contact with veneer, especially veneer on old furniture or woodwork, can dissolve the old glue and cause the veneer to lift. This is something you don’t want to happen. Water also raises the grain of the wood, which then requires more sanding.
  4. The claim of “biodegradability” made by many of the green strippers is misleading. The only reason biodegradability is an issue at all is that the solvents in green strippers evaporate so slowly that they could still be active when the stripping sludge is thrown in the garbage. Faster-evaporating methylene-chloride and flammable-solvent strippers don’t need to be biodegradable because the solvents evaporate so rapidly.