Water-based strippers - why the demand for them?

PAINT strippers are the generic name given to chemical blends designed to remove paint and other finishes from a variety of substrates such as wood, metal, brick, concrete, etc. Paint strippers can also be used for cleaning paint application tools such as brushes, rollers, and spray guns.

Traditional paint strippers have primarily been based upon various solvent mixtures, the principal one being dichloromethane. These products will strip a wide variety of paint types and generally have little impact upon the substrate over which the paint lies. Their biggest disadvantage lies in their toxicity. Dichloromethane itself is in the process of being severely restricted throughout the EU because of its toxicity.

Changes for customers - and for industry

Over the last few years, a lot of effort has gone into substituting 'safe' solvents, such as dibasic esters and dimethyl sulfoxide for dichloromethane with various levels of success. However, in general these materials are derived from petroleum, and hence are not renewable nor have a carbon-neutral footprint.

Principles behind the technology

The principle of water-based paint stripping is entirely different to solvent-based strippers. Water-based strippers rely on an organic (solvent) component to penetrate the paint layer, and carry with it the water, which normally carries the active stripping agent. When the water reaches the interface between paint and substrate, the active ingredient in the water breaks the bond between paint and substrate and the paint falls off. In general, the paint is not affected by the stripper and simply falls off in large sheets.

This action of water-based strippers has several advantages:

  • The paint is not generally affected, hence harmful materials contained in the paint will not be released into the environment. 
  • Since the stripper does not attack the paint, it is not depleted in the stripping process. This is particularly advantageous in a stripping bath, where very long bath lives can be achieved, dramatically improving process economics
  • The paint substrate is generally much more impervious to water than it is to solvent and so very little penetration of the stripper into the substrate occurs. This makes cleaning the substrate after stripping often easier and quicker than if a solvent stripper is used

 

In general, water-based strippers are not so sensitive to different paint types as solvent-based ones.