Spraying Doors in Vertical Hanging Racks
A well-arranged rack system can speed up production dramatically. March 3, 2010
Question
Any comments on spraying doors in a hanging position, both sides at once, using clips that hook into the hinge holes?
Forum Responses
(Finishing Forum)
From contributor P:
I spray lacquers and prefer them laying flat. I have enough to worry about without runs.
From contributor R:
One thing to consider is the air pressure you're spraying at. One of the funniest things I ever saw was a setup like you're talking about. The sprayer had a hell of a time trying to chase down the door as it blew in the wind, forwards and back and forwards and back...
I suppose if you had a dedicated booth and a way to attach the door to a firm rod that's attached to a firm crossbar, you could eliminate some of the issues.
Something else to consider is that overspray will want to flow towards your booth filters and as it travels towards the filters, the overspray just might migrate to a finished side. Hanging a bunch of doors also cuts down the draw that your fan will have. It will also redirect the flow of the booth exhaust.
Those are some of the drawbacks I have seen with setups like this, and if you plan to handle 20 - 30 doors at a time, you will also tie up the booth while they dry. By laying them flat you will be able to spray 20 - 30 doors/drawers, two good coats, all edges, both front and back in about 20 minutes.
From contributor G:
"By laying them flat you will be able to spray 20/30 doors/drawers, two good coats, all edges, both front and back in about 20 minutes."
Is that 20 min per door? Or do you move in a blur, like the Flash?
From contributor E:
I used to work at a custom door company, and we had adjustable door rotisseries. I was able to spray the whole door and keep the finish wet. You can run lag bolts into the ends and suspend the door between the uprights, and rotate the door to spray each side.
From contributor R:
Thirty years of pulling the trigger has taught me to be methodically proficient.
From contributor F:
Hold on here - I'm with contributor G on this one. Besides moving like a blur to cover that many doors in that short of a time, what finish dries fast enough to allow you to re-coat and then flip a door over that fast? You're saying 2 coats on both sides within 20 minutes? That's basically 5 minutes per coat per side for 30 doors, not including the time it takes to move them? So roughly 10 seconds per door with instantaneous drying. No offense meant, but that's a bit hard to believe.
I have a slow (turbine) sprayer so it takes me 20-30 minutes just to coat a single side of that many doors. Then an hour or more (depending on the finish) before I can safely flip them to coat the second side.
I too have looked at those spray hooks, but it's sounding like they're not too popular?
From contributor G:
I'll come to contributor R's defense here. He has been known to employ a degree of hyperbole is some of his posts. My take is that he meant "a fairly short time" when he said 20 minutes.
Although - using naily-boards and setting the doors in rows, one could blow 2 coats on the backs, flip them over on the nail points and blow 2 coats on the fronts in not much more than 20 minutes. The trick, of course, would be the intercoat sanding.
From contributor R:
I use very sophisticated spray racks which allow me to do exactly what I mentioned. I didn't, however, say anything about intercoat sanding. What I mean by spraying is sealing and topcoating. Nothing was said about staining or sanding, so don't read into what is not there.
20 minutes is a decent length of time in which to spray a few coats of sealer on both sides of 20 doors (not entry doors - kitchen cabinet doors) and drawers. 20 minutes is also a decent length of time in which to spray a few topcoats on those same doors/drawers. Let's not sway too far off the original poster's question about spraying doors/drawers while they hang.
No hyperbole in any of my postings, and no naily boards or nails either.
From contributor T:
I'm in the flat racking camp.
From contributor N:
I spray horizontal on a turntable with a metal Hafele drying rack (50 shelves) right behind me, into exhaust fan. I spray CV (Becker Innovat), and can usually go through a rack in 10-20 minutes (one side only). 20 minutes is usually enough to flip doors and do the other side, so I don't usually stop spraying. I use a remote pressure pot and can spray four edges and top in about 5-10 seconds per door (pressure pot really was an improvement over my gravity cup gun). I think this is the only way to go. Need more capacity? Just get another rack. I think they were about 300. Very stable, even fully loaded. Can usually do two kitchens' doors/drawer fronts and sides in a day (two wet coats, hand sanded between), sometimes third coat on fronts, if needed. I spend nearly that amount of time just prepping the shop for spraying and taking down plastic, rearranging tools afterward.
From contributor J:
Contributor N, I do it almost exactly as you do, and it sounds like your times are the same as mine. Only difference is I give about 20 minutes from when I finish the last door till I flip and start to spray the other side. I hate sanding out those little marks from the rack if you flip it too soon. I typically spray MLC Krystal or Becker pre-cat.
Here is how my day goes for one kitchen's worth of doors:
Spray sealer 1st side, wait 20 minutes
Spray sealer 2nd side, wait 20 minutes
Scuff sand
Spray fronts with topcoat, wait 20 minutes
Spray backs with topcoat, wait 20 minutes
Scuff sand
Spray backs with 2nd coat of topcoat, wait till 1/2 hour before end of day
Spray fronts with 2nd coat of topcoat
Clean gun
Go home
I use the same Hafele rack and a Devilbiss pressure pot and Devilbiss gun. I agree totally, the pressure pot is a huge step forward in terms of speed. Also, watch Hafele as the racks do go on sale periodically.
From contributor N:
I think many shops use this technique. In fact I learned about it on WOODWEB. Just wondering why you use a sealer - if it is cheaper, easier to sand? The Innovat I use is supposed to be self-sealing, sandable, and non-yellowing, but is expensive and is post catalyzed. It would be great if I didn't have to mix it up and could use a similar pre-cat sealer and didn't have to be worried about yellowing. Any suggestions? Prefer to stick in the Becker line, as I have a good relationship with the local supplier.
From contributor J:
I only use the sealer if I am using pre-cat, as I find it sands a little better than the lacquer, and it's a little cheaper. When I spray Krystal, I usually just do two coats, no sealer.
Becker makes a sealer called CareSeal. It's a pre-cat, but I am pretty sure it can go under a post-cat or a CV and it is definitely cheaper. It's real thick out of the can and needs to be thinned quite a bit to spray, so a 5 gallon pail of it goes a long way. Check with your distributor for pricing and to confirm if it can in fact go under the topcoat you are using.
From contributor S:
I have to mention one more perk when spraying doors on a vertical rack. Usually only the topmost door gets any settling dust.
From contributor X:
We have been spraying parts (doors, frames, and veneer) this way for almost twenty years. We are a high production semi-custom cabinet company and do a lot of spraying in the vertical position. We have three booths that overhead conveyors run through. Booth 1 is for spraying stain, then it gets hand wiped off. Continue on this line to a sealer booth (booth 2), which then goes through an oven and off line on to cart to go to the seal sanding department (time around 40 minutes). The second line, with one booth (booth 3), is for finish coats and rushes which also goes through the oven (20 minutes).
Spraying this way is very efficient, quick, and good quality. You're not taking up space on drying racks. We use Becker Acroma conversion varnish products with air assisted airless Kremlin equipment. A couple key things are a moving overhead conveyor system, enough flash off, good equipment, good material, and an oven. This keeps the flow moving and a lot less space is needed.
From contributor Q:
I spray vertical on site all the time with great results. I set up cables with I bolts screwed into studs from wall to wall. I can spray 40-50 doors, fronts and backs, nonstop. Then after a short rest for dry time, hit them again. You can see in this picture the paint grade doors in the background. I spray the stain and clear on the kitchen doors you see here with the same method. This is obviously before painting the trim and walls of the home. After covering the kitchen cabs, the paint grade doors are sprayed, then removed from the house and the millwork painting takes place. Obviously you will need to take into consideration the flammability of the material you are spraying and whether the area has ignition sources present.
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