Paint Stripping

In our experience the two biggest culprits of damp in old buildings are cement and modern, synthetic based paints, so, if your property is built in the "traditional" manner, as solid composite masonry and sufering from damp as a result of modern paint coating/s it could well be that stripping the paint may be the only option open to you. What can be said about Paint Stripping other than for most people, it's not a job it's a sentence; as for the rest, they simply avoid it. There are a number of processes for removing paint from masonry walls and each one should be weighed up on its own merits and approached as an exercise in risk/benefit. Regardless of what the paint or surface coating is, the objective will always be the same, to get back to an appropriate surface using the least damaging method available with minimal risk to the operator and surroundings.

Methods of Stripping/Cleaning

The method of stripping paint will fall into one of two basic categories, either chemical or mechanical methods.

Mechanical Methods - Grit/Blast cleaning. High Pressure water jets - Steam Cleaning. Wire brushing, Needle gunning or other methods involving mechanical abrasion.

Grit/Blast cleaning uses a range of wet or dry systems with a wide range of abrasive media, from very coarse gritty materials through to fine talcs, even nut shells. However, water/air-abrasive systems, even at low pressure can all too easily result in damage to the surface beneath, particularly soft brick and stonework. There are too few contractors out there who have a sufficient understanding of the damage they are likely to inflict on traditional masonry structures from the all too often heavy handed approach many have when carrying out this kind of work.

High Pressure water cleaning is unlikely to be very efective, and could easily result in setting up its own problems as a function of the amount of water delivered into the fabric, bearing in mind that water is the engine of decay. However, I have used high-pressure steam cleaning with good effect on heat pliable paint surfaces; heat from the steam softens the paint, with the high pressure delivery assisting the removal of the paint film, using steam also greatly reduces the amount of liquid trained onto the surface.

Other forms of mechanical abrasion need to be carefully considered and are unlikely to be both efective and nuisance free. However, if there is existing limewash under the modern coating then the use of an air or electric powered needle gun may sometimes be worth exploring.

Chemical Removal

Chemical solutions are based on dissolving the paint with the use of chemical formulations. While these can be a very effective method for removal, there have been widespread concerns around the world in recent years regarding the cocktail of chemicals used. Such concerns have recently resulted in the European Union banning the use of DCM’s (Di-Chloromethane) in products sold to the public. Cornish Lime now stock an extensive range of DCM free paint strippers and Anti-Grafiti products; produced by Scheidel, one of Germany’s leading manufacturers in this field, who have been producing DCM free paint stripping products for many years. There are many types of chemical stripper with the more aggressive potions sometimes acting instantaneously while others such as the Scheidel range, applied as a poultice, pasted onto the surface with the chemical formulation breaking down the paint for later removal by scraper or water cleaning, normally after 24 hrs. The Company has an extensive product range to suit a wide range of paint products and our work to date with these products has been very encouraging.

Phil Brown - Cornish Lime Company.