Safe sprayroom setup

Advice on everything from finish type to disposal of hazardous materials. December 17, 2003

I finally took the plunge and built a polyfilm room in a corner of the shop. Suffering chastisement from my electrician about the dangers of spraying lacquers and my absence of appropriate permits, I removed all electrical sources from the room - all switches and outlets are now outside - and bought an explosion-proof junction box to hook up the explosion proof fan (borrowed) in the window, switched outside the room. Now I get to investigate explosion proof lighting for the room, in addition to the light shining through the clear plastic portion of the walls from outside. If this works out, I will go the code route on the cladding of the room.

I am learning with MLC nitrocellulose primers and lacquers for speed and economy, using a Binks 2001 gun (borrowed). I do finish carpentry, not production, some off-beat kitchens, lots of built-ins and custom trim, some furniture. Basic spraying, even if it is only primer, makes me feel like my product is getting a whole lot better. On jobs requiring top notch finishing, I will continue to send the work out and suffer the scheduling problems.

Any suggestions for solid basic resources from you pros? What would you do if you were setting up for the first time? Other products than MLC (my plywood supplier now carries them, so that seems easy), or strong opinions about guns? Should I go to a pre-cat finish? I plan on sanding in the same room. How about respirators? I am using a 3M 7000 half mask with carbon filter and particulate pre-filter. And what should I do with all the dirty lacquer thinner from cleaning my guns? My guy dumped the first gallon in the dirt.

Forum Responses
(Finishing Forum)
If you are not going to be shooting conversion varnish, then it is worth a look at waterbornes. They will not eliminate the need for everything you describe, but they are much less prone to explosions and also clean up and thin with water so you have less secondary solvents to inventory and have on the shelf.

Get a good vacuum for the dust or make a downdraft table.

Use lacquer thinner in a very miserly way. Wipe out the cups with paper towels (wipe off the feed tube, too). Use small amounts of thinner in the cup for rinsing and change often. Keep two gallon containers for the used thinners; one for throwaway stuff and the other for the final rinse or two of mostly clear thinner, which you will then recycle after settling and pouring off the cleaner portion at the top for use as the first rinses. If you use several types of thinners, keep a separate container for the cleaner rinses of each type (I sometimes mix the throwaway stuff). This will save you money as well as benefit the environment. Put brushes in a bath of olive oil at the end of the day and quick clean them by squeezing in folded paper towels and then rinsing once in thinner and squeezing between paper towels again before you start work again. That way you only do a thorough cleaning at the end of a job or the beginning of a new one.

HVLP is beyond wonderful when you are spraying in any enclosed area. My system cuts overspray (versus a standard Binks spray gun) by about 90%, which makes a vast difference in dealing with the problem.

The trouble with nitrocellulose lacquers is that they tend to be more brittle and less adhesive and just overall less durable than I like. I recommend that you try water base finishes. I am currently using Breakthrough for many projects and I love it. The clears are too thick to spray well and so I thin them more than the manufacturer recommends but I have loved their performance anyway. The whites are better for spraying (though they still need some thinning) and I use them frequently. The satin white makes a great primer (finish coat too). I am currently doing a job that uses the clear Breakthrough (custom tinted by me) as a base coat for a distressed and glazed finish that is then overcoated with tinted polyurethane varnish, followed by clear polyurethane for protection. It has exceeded my most optimistic hopes for this application. Fuhr makes a very comprehensive line of water base and waterborne finishes that I have heard impressive things about, though I have been so happy with Breakthrough that I haven't gotten around to trying them yet.

Don't ever let your guys dump any chemicals on the ground or down the drain. You would be screwed if the wrong people found out. We use a company called Safety-Kleen for chemical disposal. They give you a 35 gallon drum for a deposit of $50 and you prepay for removal of chemicals. I believe it was $9 a gallon. There is no time limit. Run a ground cable from barrel with alligator clip on rim to a ground rod or water line. When it is full, you call and they drop a new can off and take the old one away. They give you all the proper paperwork for your records. This way you are covered. It takes awhile to fill up that much waste and although it will cost a few hundred up front, it is a lot less than fines in the tens of thousands.

Also, to keep things simple, it probably would be wise to go to water borne. Remember that even though it's water borne doesn't mean it doesn't have chemicals. You need to treat the waste the same as you would any other chemical.

By the way, I wouldn't tell anyone else about what your employee did - that story should be kept to yourself.

If I were setting up for the first time, I would re-route the air line from the compressor. The boss seems to have taken great time to run them perfectly level around the shops, and every outlet is a perpendicular drop from the main. That makes for a great, gradual water separation system, but I?d rather have it mostly separated earlier on in the piping than at each outlet.

We use a pre-cat lacquer at out little shop from a local supplier in the NW. I just love it. After you spray, it?s sandable in about 15 minutes. You don?t have to clean out the pump/gun fearing it will cure in the equipment, even over a long weekend. If you put a little sag in your final coat, it can easily be sanded away and returned to its original sheen with a little lacquer thinner the next day. To me, this product features a great compromise in product protection and ease of use versus production timelines. At $10 per gallon, it?s also relatively inexpensive as far as finishes go.

That being said, if I ran my own shop, I?d go purely water based. I?d do it solely for the health of my crew and myself. With good cross ventilation, an approved respirator, gloves and all the little things I do with nasty, solvent based products, all the employees would just be that much better off. I suppose at that point, I?d have to wonder if the customer would really be that much worse off. We also pay almost $50 per gallon for our small quantities of water based finish. I?m not saying that?s not worth the health risk or dry time, but I can appreciate the choice.

First thing I would suggest is get plenty of liability insurance if you don't have it already.

If you use water-borne systems, send a sample of your washings to the local water or sewerage company (I assume it's the same in the States as here in the UK?).

They will analyse the sample and let you know if you can discharge it to the foul drain (sewer, not rainwater) and how much a day you can discharge. You can then pour your washings down the sink or loo.

If this is not so, then contact a local waste disposal company. We also use Safety-Kleen as they supply a solvent parts washer (normally supplied to auto shops for degreasing engine parts) which we use for washing out paint brushes. They come and change the solvent reservoir every 6 weeks and fill in all the paperwork.

From Russ Ramirez, forum technical advisor
Excellent point about waterborne waste discharge into sewers - exactly right.

I would have expected a little more alarm on the issue of pouring solvent into the ground. Introducing solvents into the atmosphere is one thing (and okay with me) because the atmosphere can take care of what us finishers are shooting (large manufacturers not included), but the ground does not so easily correct the pollution we introduce into it.

The fact that water table contamination is such a big issue makes pouring anything into the ground an egregious act, and one to be avoided no matter what.