Spray Room Cleaning and Hygeine

For a quality finish you need a clean shop and spray room. Here's advice on getting there. January 2, 2012

I'm interning at a shop, and trying to help them out in some process improvements. What you are doing in your spray rooms to control your quality and keep the pieces you spray contamination free and drying properly?

The AC in the room has broken since I started, and the wall unit is being used for the time being. Although it isn't keeping the temps down around 75 degrees, it's at least not 95 degrees. I know this could use improvement.

I had the idea of using a dehumidifier. When it rains, it effects the dry time greatly. The room isn't air tight - we basically just have a closed off room with a couple tables and a spray booth fan. We have some dust issues when we paint, and I think sanding and tacking in the spray room is the culprit.

Forum Responses
(Finishing Forum)
From contributor Z:
Well, after looking at your company's website, I have a few suggestions. First of all, clean the shop out! That's right, move everything outside and clean it from top to bottom and then clean everything out before you bring it back in. That place looks like something you would see on one of the hoarders-buried-alive episodes. The dust particles are practically blotting out the photos. Just how big is this shop, and what kind of room do you have?

From contributor S:
I agree - a good place to start would be cleaning the main shop area. I found the most impact I can get as far as improving spray room quality is a clean atmosphere. And that does not start at the spray room door. Employees need to develop a habit of keeping work areas clean. Those with bad habits of not keeping the shop clean will not keep a spray room clean. When running fans in the spray area, airborne shop dust and even the dust or dirt on our main shop floor seems to find its way through two doors and a separation room. I would suggest no sanding or prepping in the spray room. We sand in the shop, prep in the next room, and then only spray in the spray room. And then we clean the spray room on a regular basis. We have a small shop, so we schedule spraying so it does not coincide with dust creating activities in the workshop. For us, this means spraying during the evenings or weekends sometimes.

From contributor M:

Anything more than occasional metal working in a wood shop is a bad idea. If I need to cut, grind, or sand metal I do it outside whenever possible. The possibilities for contamination here are endless. If I have to do it inside I do it on the floor or something.

Wash your hands frequently. Instruct employees to do so. I treat my final sanded surfaces as if I were handling food.

It's okay to spray stuff down with WD40 and other lubricants, but be mindful of where it lands. Once again this is another good opportunity to wash your hands prior to handling wood that is to be finished.

When I need to clean all of the dust out of my shop, I stick a couple of box fans in the back door to exhaust, and another in a widow to bring air in. I start in a back corner and blow all the dust from one end of the shop to the other and eventually right outside. During this process I run my dust collector with all the blast gates open to help circulate air and pick up some dust. Wear a mask or a respirator when doing this! This takes me about an hour.

Install ambient air filtration as well. If you have fine dust settling all over the place on top of everything, you need to do a better job, either capturing it at the source or while it's still airborne.

If you're having dust contamination within your spray booth, your make up air system is not keeping up and your booth is sucking in dirty air from the rest of the shop.

As far as temperatures, consult the manufacturer of your finishing products as to the recommended temperature/humidity for application and drying. Much of this differs from product to product.

From contributor J:
One thing you're doing right is asking questions and being open to suggestions. As an intern, use your common sense, which I believe you have. To answer a question such as yours would take pages of information, and not just for the finish department. You'd be amazed at what kind of finish you can get spraying in a non-sterile environment. I've had to spray on construction sites many times, so as with all the other suggestions made, try and keep in mind some fundamentals.

1. Remove/blow out all dust and sawdust, starting from one end of your shop to the other end. Keep the fans going and the dust storm moving in one direction - out! Repeat at a minimum of 3-4 times. Top of shop to bottom needs to be blown off.

2. Pick the perfect time to spray. If it's raining and your schedule permits, hold off the final coats until the moisture content drops per manufacturer's specs. (You'll never see perfect conditions.) If it's super hot, wait until the evening to spray finals.

3. Remember that constant wiping down of your woodwork will create a static charge to the piece and this will attract every single piece of garbage floating around, especially if you're spraying conversion varnish, etc. If you can't afford an air nozzle that dissipates static charges, you can use denatured alcohol as a good stop gap.

This list could go on and on! Just pay attention to where the contaminated air is coming from - in spray booths, it sneaks through cracks and small seams, etc. Unless you're spraying in a perfectly temperature controlled downdraft booth that has recirculating air that's been filtered, and air temp and moisture content is regulated, and you're wearing fresh Tyvek suits from head to shoes and testing the particulate fallout rate with a piece of 1'x1' black Plexiglas to see just how clean your booth is... You're gonna be prepping and cleaning constantly to fight for a consistent smooth finish. Or you could use pre-cat lacquer in a satin to dull sheen, have a fairly clean environment, and get away with murder by using a quick rub down after the finish has dried with the back of the sandpaper!

The short of it... Just know your coatings limitations, understand the environment and which direction the air is flowing from (start to spray from there). Keep the shop, your equipment, and your schedule clean and ready for the "didn't see that coming" things that finishers deal with day in and day out.

From contributor A:
I wipe down parts with a micro rag dampened with water. I spray waterborne finishes. I've read to mix water with denatured alcohol. Honestly I never knew why they did this. Is this to control static? When spraying white,I do notice things getting into the finish and can never figure out where the particles came from.

From contributor J:
I would imagine that is their intent. Personally I'd leave the water out. I like the micro-rags also but will lean towards the car finishers style with some tackiness to it (feels and smells like linseed oil or very diluted varnish on the rag). On the static subject, if you're using an air assist or airless, the fluid line is surrounded by a static charge, I would assume from the material rushing through the spray line. I'm a finisher and not a scientist so that's as far as my knowledge goes. It took banging my head against the wall trying to find out why all prep work for cleaning many times felt like a waste and more like a curse!