Replies

1. 
   Kevin | Apr 19, 2007 07:06pm | #1

   Latex doesn't spray nearly as well as just about any other kind of paint out there, and latex "enamel" is famously more difficult to get a decent flow out from.

   Your reduction schedule, via Fuji, sounds reasonable to me. But I've learned that with latex you really have to go with what works best and use suggested reduction schedules as merely good advice or a very general guideline.

   More Floetrol would have helped. I like to use closer to 20+% floetrol and then I reduce with water until I get an acceptable, if less than ideal, flow from it. Of course as with any paint or finish, the more you reduce the more the risk of runs or sags is increased and need to be accounted for.

   What I like to do is what is commonly referred to as a "painter's two-step." Which is to spray on a layer of paint/finish in two steps rather than in one fell swoop. I'll put on a medium wet tack coat on everything and then come back (before the tack coat dries or flashes completely!!) and put on another slightly wetter coat.

   How this works is that some of the solvents/water dries out of the tack coat and this allows the second coat of the two-step to be applied heavier while reducing the risk of runs or sags that would be caused if the same amount of paint/finish had been applied in a single step rather than in two steps. Some of the solvent/water in the second coat will disperse into the tack coat, thus effectively reducing the viscosity of the second coat, which is what enables it to hang better without sagging or running.

   Even with a painter's two-step I sometimes find that I have to let the latex dry, sand it lightly and then give it a final light coat. Mostly because I've found that over-thinning latex too much causes tiny bubbles to be a slight problem, although they are vastly easier to deal with than a run or sag. In such a scenario I will thin the final coat much more than the previous coats because I already have the color and all I need this last coat to do is to flow out - so thinner is definitely better than thicker (to a point...!). And since it only has the one task to perform, I don't have to spray it on nearly heavy enough to cause a run or sag. I just want a smooth final appearance. 

   I would suggest sanding your sags out and then double the amount of both Floetrol and water and then spray that over it all as a final coat.

   I assume you have the back out of the bookcase so that it's just the shell and the shelves you're painting? If not and the back is installed too, then I would suggest either removing the back or proceed with your brushing the final coat idea. Inside corners (where two angles meet to form a 90 degree corner) are ofen difficult to spray decently into with any equipment which requires air to atomize the paint or finish. The phenoma is sometimes referred to as the "caged Fariday effect" which is actually a term from electrical engineering which roughly equates to what happens when painting. Anyway, a compound inside corner (more than two surfaces meeting to form a compound 90 degree corner) such as where the end of a shelf, the side and the back all meet, are nearly impossible to spray paint evenly even with materials which flow out superbly. With something like latex it would definitely be mission impossible to spray a compound inside corner and have it come out looking good.

   
   

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   Edited 4/19/2007 12:07 pm by Kevin

1. 
   user-72272 | Apr 19, 2007 10:06pm | #2

   Kevin -

       I spray a lot of my book cases with latex and a Fuji sprayer.  I have found that using equal amounts of Floetrol and water works for me.  Typically I thin using about 15% water and 15% Floetrol.  If it is warm and the paint is not flowing out because it is drying too fast I suppose you could go to 20% of each additive.