For those of you that have a spray booth, do you do all your scuff sanding between coats inside the booth, or do you move all the parts out of the booth and only do spraying of finishes inside the booth?
From contributor R:
Even with an installed vacuum system and good air movement we still have to wait quite a while to assure airborne particles don't settle on finishes. Additionally, particulates on the floor can still be stirred and become airborne, so we do scuff sanding and all sanding outside of the booth. I know some think this is excessive, however re-doing final coats is more costly in time than materials especially if the workload is large. For a one man shop with adequate time and limited space it may not be as important.
Dust is the enemy to film depth, clarity, and adhesion. In every case of issues with clarity, depth or later, adhesion, dust proved to be the culprit nearly 90% of the time. (The remaining 10% was usually related to application or finish chemistry.)
Tests have proven that no matter what the regimen, everyone slips, and everyone becomes lax over time. Preventing dust infiltration is a very crucial step in achieving a clear finish with depth. That being said, it stands to reason that sanding in proximity to finishing areas should be absolutely forbidden in all cases, at least in high volume plants.
If one considers the finishing process itself, it is easy to understand this fundamental principal: Finish materials, before they are cured, act like adhesives. Dust clings and collects in and around adhesives.
As proof ask any old timer what he uses for a tack rag for oil varnish, and he'll tell you: wet a cloth with some thinned varnish. Therefore it stands to reason that eliminating the risk of dust infiltrates should be the goal of all Finishing Department heads.
Over the years my company has striven to instill good housekeeping practices and strategic finishing steps for all our partner factories. The result has been a significant decrease in finish failure and a significant increase in complements for our furniture, and so, more business.