PDA

View Full Version : Spray Painting Ideas



lenord
04-24-2004, 08:49 PM
All,

I regularly have to spray paint small pieces of metal. Brackets and the like. What I have been doing is using a large cardboard box, on a workbench, taped up well, and the shop vac hose in a hole on the side to get the fumes out. It worked well enough until now.

Now, I have a LOT of spraying to do, multiple cans worth, and find the shop vac is not getting the paint smell out well enough to suit me. I've changed the filter, not much better.
Does someone have a good idea for filtering out the paint fumes smell in a semi production type shop ? Somewhere between 3-5 cans a week maybe. Should I build a regular booth out back and have an exhaust system ? What kind of filters do I use ?

Thanks
Lenord

coles-webb
04-24-2004, 09:50 PM
The problem with using a vacuum or some people use a box fan to suck out the fumes is that you are sucking the flammable fumes past an electric motor. You would probably benefit from building a proper booth even if it is only the size of a small shed or greenhouse. You have 2 basic choices, a positive or a negative pressure booth. A negative pressure booth sucks the fumes out. It requires a fan of probably at least 18 to 24 inch dia. that is driven by an offset explosion proof motor. You would have filters for the air coming in and filters to filter paint particles out before they go through the exhaust fan. You can use the better quality filters for furnaces or buy actual spray booth filters from an industrial supplier (they are not that expensive and usually come 20 by 20 or 20 by 25 inches or larger). You need to have a chimney to get the exhaust fumes up and away from everything to give them a chance to disperse. This can be a disadvantage as neighbors usually frown on paint booths next door. Ensure also you know the wind direction while painting to avoid the fumes going into a neighbor’s barbeque or getting sucked in someone’s air-conditioning. Just because the fumes are gone out of the booth doesn't mean you are not responsible for them anymore. The disadvantage of a negative pressure system is that it will suck air in from everywhere not just the intakes and any dust or bugs will possibly come from cracks or joints also.

The other option is a positive pressure system that has a fan outside the booth pushing air through filters, though the booth and out filters at the other end( through a chimney again). This is a better system as it will also blow air through any cracks or joints blowing dust and bugs out. The fan is also outside pushing fresh, clean air through filters which means no problems with fumes going through an electric motor. A box fan or 2 would work for this. The same types of filters as mentioned above will work. All lighting in either types of booths should be explosion proof, sealed or outside the booth shining through Plexiglas along with any other electrical equipment explosion proof or sealed. Parts or the racks they hang on should also be grounded to earth to avoid static electricity. For your own protection I would read the MSDS Sheet, use rubber gloves and a respirator with the proper fit and filter (not a paper dust mask). To be extra safe disposable coveralls can be purchased. Ensure it is not too hot, cold or humid in the booth. I wouldn't recommend painting too late in the day as dew can affect finishes also. Unfortunately these types of booths are limited to nicer climates as they require warm dry air or a heating system. But on the up side you can paint parts and let them dry without any worry of the finish getting damaged and carry on in your shop with other work. Putting a good finish on a product completes it, putting a so-so finish on a product makes it look so-so no matter how well it’s made. With this type of booth you can paint the better quality types of paints that give better more durable and longer lasting finishes than spray cans although I have seen 2 part epoxy paints that now come in spray cans but I have not yet tried them. And as a last point technically you have to follow all laws and regulations dealing with this type of equipment (sorry I had to add that). Good luck.

Mike

Forrest Addy
04-24-2004, 10:46 PM
Cardboard appliance boxes have been my quick and dirty spray booths for years. Cheap box fans have exhausted the fumes and expired furnace filter captured the overspray. it's a great simple cheap system needing only a window to blow the fumes outdoors. Usually I paint outdoors under open shelted so I don't need the fan and filter stuff.

There is no spark hazard with box fans becuase induction motors have no comutators.

In order for solvent fumes to ignite they have to be in a certain concentration with air. Try this experiment out of doors in a 20 ft square cleared area: Fill a spraygun with thinner and spray a quick burst at an ignition source like a 4th of July sparkler. You can't hardly get the solvent spray to ignite from the sparkler unless the fog is right on it. If it does ignite it's impressive so don't forget to let go of the trigger.

Solvent explosions and fires are rare in painting operations free of ignition sources (smoking and welding for example) but they are of such high conesequence that the underwriter's require elaborate and expensive safety making no allowance for scale ofoperations. A spray can and an industrial scale spray booth applying 500 lb of VOC coatings are equivalent in terms of risk.

Use common sense (NO smoking) and safety gear, have a charged garden hose handy, and spray to your hearts content in a cardboard or visqueen spray booth vented with a box fan out a handy window. Micheal Dresdner is a painting guru. He wrote a great article in Fine Woodworking on budget DIY paint facilities about a year ago.

Explosion proof motors with spark proof fans, commercial paint booths and similar precautions are like running with the big dogs but unless you're painting cars or three or four other large projects a day they are overkill diverting funds from other necessities like tooling, books and machinery.

[This message has been edited by Forrest Addy (edited 04-24-2004).]

lenord
04-24-2004, 11:06 PM
Forrest,

The refig. box, DOH !, should have thought of that one. Thanks !

I can get whatever fan/motor and filters I need. How do I make/can I make it a postive pressure booth ? I don't have a window handy. I also get small particles in the finish and would like to avoid that as well.

I have a barn out back I can put a booth into if the positive pressure thing is too hard to do.

Can one of you explain that in a few sentences so I can get it please.

I found the industrial paint booths. Not too expensive, but I like the reusable box idea better. I'm a cheapskate.

Thanks !
Lenord

CCWKen
04-24-2004, 11:29 PM
I see you're in Texas. If this is a business, 3-5 cans a week can get you in hot water with TCNR. If you don't register and they catch you, it could mean a $10,000 fine per day. If you do register, you can't use cans in production. Most spray cans exceed VOC limits in Texas. (5.0 allowed for special coatings, otherwise it's 4.3 limit.) I guess they only sell them here for the Taggers. You can claim a permit by exemption if your total VOC's per month don't exceed 50 but the 5.0/4.3 rule still applies.

Just removing "paint odor" from the shop is not enough. You must filter the solids and eject the exhaust 12' above any building within 150'. (Including yours) The exhaust must be straight up without interuption or difusion. (No caps). There can be NO visible emissions.

You might want to think about going to powder coat. Many companies have done so and no VOC's to track.

Alistair Hosie
04-25-2004, 03:33 AM
I saw a comercial fold away spray booth once .It was made of plastic sheeting which was held together with a plastic rod system with fittings on the end.
like a wendy house for children, seemed pretty good and folds away after use. Alistair

coles-webb
04-25-2004, 06:21 AM
Unfortunatly lots of rules and nasty fines if you get caught. Eastwood(see link below) sels hotcoat systems at a reasonable price. They also sell small booths or at least give you some thoughts as to how they are built. They also have a tech library giving tips on use of thier products.

Mike

http://www.eastwoodco.com/jump.jsp?itemType=CATEGORY&itemID=460

wierdscience
04-25-2004, 09:44 AM
Did you see?-

http://www.grizzly.com/products/items-list.cfm?&gid=EFBBC934-AD75-46CF-A7 D9-46B16DB24FAE&site=grizzly (http://www.grizzly.com/products/items-list.cfm?&gid=EFBBC934-AD75-46CF-A7D9-46B16DB24FAE&site=grizzly)

search for G0532 AND G0533


Even if you don't want to split with the coins its good for ideas,its got it all,filters,serious blower and it folds up.

[This message has been edited by wierdscience (edited 04-25-2004).]

coles-webb
04-26-2004, 06:42 AM
I like it, it give me all kinds of ideas as I wouldn't pay that much for it but to build is a different matter. Thanks for the grat link.

Mike

lenord
04-26-2004, 08:06 AM
Thanks for the info. everyone.

I think I will look around for a local firm to do the powdercoating/painting. It just seems easier. If it gets too expensive, I'll look into powder coating here again. I have the IR heaters for winter I could use.

Lenord