Replies

1. 
   SteveSchoene | Feb 26, 2011 10:22pm | #1

   If by lacquer you mean standard nitrocellulose lacquer, it will dry in cold conditions.  The lacquer thinner just has to evaporate, there is no chemical curing process going on.  The problem you might incur is that cold temperatures off also mean high relative humidity, which can be a problem. 

   If you are talking about a catalyzed lacquer, or the acyrlic waterborne finishes called lacquer, then the answer is you have to have the wood, the finishing materials, and the space warm enough to apply it and keep it warm enough for long enough for it to become well cured--at least several days. 

   Besides, if it is cold enough to worry about the finish drying or curing, it is a lot colder than I would tolerate doing the job. 

2. 
   AutumnWoods | Feb 27, 2011 03:00pm | #2

   Temps are Tricky

   Some factories "bake" their finishes to help them dry faster, but it can be a little complex.  First you need to have everything above 55 degrees and preferrably more like 65 to 70.  This means the Finish in the can, the air in the shop, the air in the compressor if possible, the workpiece, etc.  I'm not saying you won't get away with spraying it cold - I'm talking about maximum performance and cure.  This is especially important with catalyzed finishes.  I've tried blowing heat across something to get it to dry and it can bubble the finish or blush if you overdo it.  I think an ideal box for speed curing would be one that has a fan blowing out to expel fumes and a way of drawing warm air into it  to heat the finish.  That way nothing's blowing across it, warm dry air is evaporating the thinner in the finish, and excess fumes are being carried off.  Anyway, that's my 2 cents.

1. 
   SteveSchoene | Feb 27, 2011 06:49pm | #3

   Remember to keep the distinction between evaporative finishes--shellac and NC lacquer.  These will dry fine in quite low temperatures. Forties will be fine.  It is just as olvent, alcohol for shellac and lacquer thinner (a very volatile mixture of thinners and solvents) that must evaporate.  Cold slows evaporation, but not to a meaningful degree in this context. 

   But, reactive finishes, which include varnish, waterborne finished, and catalyzed lacquers. conversion varnish.2K poly, or polyester finishes require  chemical reaction to take place in the curing process.  These chemical reactions are much more sensitive to temperature than the simple evaporation with plain NC lacquer.  Some may tolerate cold better than others, but still any finish in this class should be used in situation where the temperature is warm enough.  And, as AutumnWoods points out, all aspects must be sufficiently warm, the wood, the finish material, and the air, and these must be kept warm enough for the cure to be substantially complete--several days at least for most reactive finishes.