Well a lot depends on the exact substance and I am just a link to the chemists, not a chemist myself, but:
- what you are applying is a product in solution (ie product and solvent mix). When the product cures the solvent carrier evaporates off and the product that is left behind can harden and bond with itself/the surface it is applied to.
- just because you add fresh solvent to the surface doesn't necessarily mean this new solid/cured/bonded coating is going to redissolve... it may have had heat to dissolve it in the first place, it may have been in a powdered form or whatever. The cured product will be different from that raw ingredient even if it it just a thin and cured coating of the product, rather than a loose powder.
- so when solvent is reapplied, if it is the right kind and applied in the right way, there is a chance of at least some of the product redissolving, for sure. But the reality is that it is a solvent/product mix (so not pure solvent) being applied, in a very thin form, and it will not be raw enough to have much effect.
Get a cloth and some water and try to remove the Dulux emulsion on your walls - it is a water based paint, so surely water as a solvent will make it wet and remove it? You'll find it doesn't - or doesn't easily. Cured/dried products have different properties to when they were in solution.