Scuff Sanding in the Booth

Will scuff sanding between coats inside the spray booth lead to problems with finishes? September 17, 2012

Question
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?

Forum Responses
(Finishing Forum)
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.


From contributor C:
Starting out with a clean spray booth to begin with helps cut down on air born dust. A little water sprayed on the floor via an inexpensive fertilizer sprayer keeps floor bourn dust at bay. At the end of the day a good booth cleaning with a leaf blower (including the booth filters) gives you a head start on having a clean booth for the next morning's production. Most sanding of coatings happens in the booth unless another project needs to be sealed, and then whatever needs sanding is moved to the outside while the current project gets coated. Once the majority of the sanding residue is blown off using the Gershin tac-rags works quite well for a final wipe prior to the final coats being applied.

From contributor G:
I do all my scuffing in the booth. I don't have any problems with dust and I don't spray the floor.

From contributor I:
We run two booths - two AAA sprayers in one and we get a lot of dust. We scuff anywhere, inside or out. The only thing I prefer to keep outside is primer sanding. Otherwise once a week cleaning and we're fine with dust on the floor. We rarely have problems with airborne particle issues.

From contributor Z:
We sand in the booth because we don’t like the buildup of dust outside the booth. We clean the booth once a week, blow it out, and it works great.

From contributor O:
This is a great thread for anyone working in a high-volume environment, however I would like to interject some observations gleaned from 18 years working with large plants in South East Asia, fabricating furniture and fittings for the 4-6 star hotel industry.

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.

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