Examples of formulation
Everyone knows the "king" of the solvents used for paint stripping, dichloromethane. The molecule of this solvent is in fact able to penetrate the paint in a very short time and raise it from the substrate. Dichloromethane is able to easily remove paints such as polyesters and epoxypolyesters in a few seconds, but it must be combined with other ingredients to make it functional even on more resistant paints such as epoxies. The historical formulations were based on dichloromethane, formic acid, phenols and dodecylbenzenesulphonic acid, which managed to keep the acid solute in the solvent. Additives completed the formulation, such as for example corrosion inhibitors or oily products which stratified on the surface limited the evaporation and the harmfulness of the paint stripper. These products were number one, but were then replaced by pyrrolidones, especially by the NMP and then by the NEP. Both portentous, were declared harmful and reprotoxic, for this reason they are now less and less used, together with other known solvents such as methyldiglycol. The search for new raw materials at the moment seems to have stopped on the renowned Benzyl alcohol, which seems to have no competitors on a par with low toxicity. Benzyl is practically active on all types of paint and is compatible with a large variety of other solvents, bases and acids. Its functionality even when cold makes it preferable also to other noteworthy solvents such as DMSO, which seems to have efficacy in reasonable times only when hot and in a strongly alkaline environment, where it manages to complex in a super-base. Furthermore, DMSO is not always well regarded because of its smell and its ability to penetrate tissues and skin. Then there are other solvents such as DBE (dibasic esters) which have the ability to denature and slowly penetrate even in multi-layer paints. This solvent is increasingly used, especially for those paint strippers declared "green", in fact it does not present any toxicity to humans or the environment.
As for gel paint strippers, the same indications apply as traditional paint strippers, however, there are greater difficulties due to the physical state of the product which, being gel, finds it more difficult to penetrate the paint. For this they often use reaction catalysts such as hydrogen peroxide, amines, ammonia or strong acids. Certainly a higher speed of paint stripping is guaranteed thanks to the use of volatile solvents which, however, are not always desirable, except for the stripping of the wood in which solvents such as acetones and dioxolanes are still widely used. The gelling agents used are for example the classic modified carboxymethylcellulose for solvents such as Metocell, or solutions such as kaolin or some bentonites that make a "paste" effect, less sticky.