As nail professionals, we are surrounded by dozens of bottles, pots, and jars. And it all costs money, so we want to use every single last drop of our products. Therefore, it makes sense to many of us to decant the last bit of a product into a new bottle, and throw away the old one. But should we?
Depends on how you look at it. From a health and safety point of view, it is ok to do that with products like nail polish, gel, L&P, etc., since no pathogens can survive in them. That is not the case, however, with creams or lotions, especially ones that you might use your hand to take out of their pot.
There are other reasons, though, for why you should NOT decant your old product into the new. First of all, you could be taking some dust or glitter with it!
But let’s look at it each product type separately.
Old nail polish will probably be missing a lot of its solvents that will have evaporated since the time it was first opened. This is, after all, the reason why it becomes thicker. By decanting it into the new bottle, we would be messing up the balance of the fresh product’s formula, something I am sure no nail professional wants. The best option, in this case, would be to add a few drops of the base coat into the old nail polish (preferably of the same brand), give it a good shake, and continue using it.
A hybrid gel polish that contains solvents can become thicker over time by losing some of them due to evaporation so, again, we should not be mixing it with fresh product. If it has been properly used, a good shake will most likely bring it back to a good consistency. Remember, it takes more shaking/blending than nail polish since they have a very different consistency.
Pure gel polish doesn’t have any solvents in it; therefore, it is not likely to become thicker. It can, however, contain dust, glitter, or lint.
The same goes for sculpting gels, builder gels, etc.
The newest builder gels in a bottle may fall into the pure gel or the hybrid gel category. Depending on whether the brand you use contains solvents or not, follow the same guidelines as for the gel polishes.
Finally, monomer liquid should not only not be mixed with a new batch, but it should also never be returned in its own bottle once it has been decanted for use. Leftover monomer in the dappen dish contains traces of polymer powder and is therefore contaminated. If returned in its bottle, it will affect the polymerization. You should not keep it in the dappen dish to use on the next client, either, for the exact same reason. It should be poured into a paper towel, and get discarded safely as all solvents should. Portion control is the best approach when using monomer so that you do not waste it.
Use your products safely and with respect!