A french polish question...

[Kalimna]

Greetings folks,
I have a quick question for anyone who french polishes. How long is french polish likely to last for in bottle? I made up some FP about 3 years ago (flakes into isopropyl alc and stored in plastic screw-top containers) and would like to know if it is worthwhile still using it, or should I make some fresh?
I seem to recall that there is a simple test to see if it is still viable or not, but perhaps I would be best to start straight over?

Cheers.
Adam

 

[Sgian Dubh]

It's probably best to mix up a new batch from fresh flakes if available. But you can test to see if the existing polish is still viable. Put a small blob of the stuff on a hard surface, about the size of a finger or thumbnail. If it dries hard overnight it should still be good. Obviously, to be sure of proper curing the fresh batch approach would likely be the best option even though there may some additional cost involved in purchasing new materials. Slainte.

 

[Kalimna]

Thanks for that - seems to tie in with what I thought. I shall see if a sample hardens overnight. Are you saying it should be rock-hard? I still have plenty of flakes (stored in the dark, wrapped, in a toolbox, in the garage) and IPA, so mixing up more shouldn't be a problem. I just don't like to waste things if I don't need to (compare with several small bottles of Tru-Oil I had decanted off from a large bottle a few years ago thinking it was more cost effective that way. Not really, it seems!)
The FP will be for some acoustic guitars, so that might be another reason to mix a new batch.

Cheers,
Adam

 

[Sgian Dubh]

It shouldn't be soft anyway, but well cured is what you're looking for. When I said a hard surface I was thinking primarily of a piece of glass, although other surfaces would probably do, e.g., some plastic laminate, something anyway that doesn't absorb the polish at all in the same way wood does. Slainte.