MITRA Forum Question Details

In theory, I would not use milk or egg white as they can eventually become insoluble if you fail to wash them out. Gum Arabic will not do this but again, in theory, the dry residue would likely become incorporated into the paint. I keep writing “in theory” because in practice, this is unlikely to cause any real problem. The percentage left in the paint would be infinitesimal.

There is really no issue with saliva (HOWEVER make sure to not put the brush into your mouth as there be some remaining pigment or metal ions, also do not transfer the materials from the brush to your mouth).

On the other hand, I also knew a painter who would shape their expensive kolinski brushes with the wash water and then reinforce the point with a single ply of toilet paper. They would then remove that at the beginning of the next painting session. It seemed to work well for her.

​I think methyl cellulose would be worth considering for this application. 

Methyl cellulose is generally a weaker, less brittle adhesive than gum Arabic and may be a better solution. It should still be a very weak solution. It would function the same in that it could be manipulated our by hand if of the proper weak solution (you would need to do experiments to find this out yourself). Like gum, this means that a tiny amount of it will get incorporated into the oil paint but at that level I cannot see it causing future harm.

Hair conditioner contains a vast number of components including non-drying oils/fats, emulsifiers, and a wide array of materials that would certainly condition the hairs of your brush but could really compromise any paint that it is contaminated with. It may be all right if one rinses the brush in water and then an organic solvent before using with oil paint. I would caution against this practice unless one is willing to be scrupulous in the above practice. This reminds me of the practice of sign painters keeping their sign painting quills in lard or mineral oil to keep them conditioned. These needed to be scrupulously washed in organic solvents before use or the sign paint would not “dry”.