Staining Racks for High Production

Ideas for racking systems for high-volume staining of sawn wood members. June 30, 2014

Question (WOODWEB Member) :
I need to be able to stain over 20,000 10' 4x4 (untreated) and 13,000 10' 1x8ís. I will be using a water-based stain. I have looked at moulding sprayers but that will require two passes through. It looks to me like it would be just as simple to lay them out and spray by hand with an airless sprayer to save all the extra handling. I know we would still have to flip them but that wouldnít be as bad as stacking and re-stacking, would it? Iím also open for other suggestions.

Forum Responses
(Finishing Forum)
From contributor R:
I'd think about dipping.

From contributor J:
How about a pressure pot setup?

From the original questioner:
I will experiment with both of those options.

From contributor N:
How many sides will be visible? Is this stain an oil modified acrylic semi-transparent or a stain that will receive a clear top coat or is it a solid color? Is your wood S4S or re-sawn? If four sides (back, front and sides) or six sides (back, front, sides and top and bottom) will be visible your biggest challenges will be racking them while three or five sides dry then getting the last side after the other sides have dried and having a drying rack that will hold a lot of pieces, be movable and be able to be broken down. If you have one side buried then of course just do your finish side last.

If your wood is S4S and you're going semi trans or a stain that would be top coated later I would go with the pressure pot and gun as chances are you'll get away with minimal or no wiping. If you have resawn material, chances are you'll be back brushing or rolling to work the finish into the nooks and crannies be your finish semi-trans or solid color. If your finish is a solid color exterior stain I'd use the airless.

I've done a lot of this kind of work and the builders I worked for had a great rack design that was inexpensive to build, strong and could hold quite a bit of wood and allow five sides to dry without screwing them up while they did. Basically it was a 4x4 attached to a plywood base with 1 and 1/4" holes drilled through it at 4 or 6" intervals where I would place a 1"x 5' steel pipe, leaving me over 2' on either side where I would stack my wood - just place your boards on both sides of the 4x4 and when it fills up add a another pipe working from the bottom. Of course you have to have a pair for it to work and in your case four or five or more pairs will be the way to go. At 4" intervals you'll get 18 runs (bottom couple of feet of the 4x4 post will need to be well supported to the base) with only (six) 1x8's per run that's only 108 per pair of racks, but 540 if you have five pairs!

From the original questioner:
The 4x4ís are sanded four sides and the stain is a water-based solid with no top coat. These are going inside but they want to create a patio atmosphere so the design and finish are to look like it belongs outside if that makes sense. I need to be able to stain close to 500 per day to be able to meet the timeline. I have plenty of room for whatever kind of racking or drying area I need, or at least I hope I do.

From contributor A:
I would rather have the molder sprayer myself and rack if needed. The best way to finish this type of product would be vacuum coating. If you do a lot of this kind of product you should look into it. The equipment isnít low cost and there is some setup but the product can run at up to 70 plus feet per min. Water based stains with IR ovens and the product is dry to pack when off loaded.

From the original questioner:
We do a lot of composite wood panels but this is our first large scale project with lumber. We have an IR oven and a large automated spray booth but handling these 4x4ís multiple times doesnít seem like a good idea. The 1x8ís could go through that system I believe. I am going to look at a molding sprayer tomorrow.

From contributor N:
It's a simple design: 2.5' square 3/4" plywood base with a 1' or so tower made of 1x6's screwed to the base with diagonal supports. This tower has a 4x4 cavity in its center where you place an 8' 4x4 post. The post has holes drilled through it at whatever interval you like. Where you place lengths of steel pipe that will extend out horizontally from either side of the 4x4 (we had two sizes one made for 3/4" pipe for lighter pieces and 1" pipe for heaver pieces).

Simply set your pair of racks at whatever distance apart that works, load the finished wood onto the pipe ends and when that run is loaded add another pipe to both racks for more wood, adding runs from the bottom up works best. I used these racks for back priming and pre-finishing exterior siding and trim and interior trim. One project was over 100 upscale condos where every piece of exterior siding and trim had to be primed all six sides (miles and miles of western red cedar) and pre-finishing the interior trim packs; casing, window surrounds, base, and closet packs, using the same four racks for the two years it took to finish the project.