View Full Version : Vapor condensor for painting?

06-10-2014, 5:52 AM
I was over at my buddy's working on his Chevy. It's a frame-off deal, and the chassis has been prepared and is ready for primer. Anyways, he rigged up this enormous condenser (like, 15 feet high) out of copper tubing coming out of the air compressor and before the paint gun to draw any water vapor out. He claims that if there's any water at all in the air it'll show up in the paint/primer. I understand that is true on a theoretical level, or if your surface or whatever is literally wet, but is this really necessary? I hardly think that would make any difference at all considering the typical East Coast climate of at least 90% humidity all the time.

Does anyone use anything like this? I ask especially because I'll be shooting a bike of my own in the next couple months...

06-10-2014, 6:22 AM
Your friend is correct and was probably fucking tired of moisture in his air.

Commercial water separators are commonly put inline near the disconnect to dewater compressed air after it has cooled a bit during its travel from the compressor. This not only makes for better painting but protects plasma cutters and other sensitive gear (consumables last much longer). Water vapor certainly does fuck with paint.

Google "Franzinator" for a famous homebuilt design that's been widely used.

To protect our plasma cutters my boss used an old trick. He welded a chamber from some pipe fittings with a piece of expanded metal to restrain the contents. He had me skin out a large box of tampons and fill it, then we installed it on the end of our pipe run with a small drop leg and drain valve below it. When our department head was walking a client through the shop they saw me biting then ends off the tampon wrappers with my teeth next to a pile of "white mice" on the desk. Funny shit....
The filter worked and the expansion room plus dropleg got the condensation. It gets humid in SC.

Inline filters which use a roll of toilet paper are common (Motorguard etc) and often used in painting and plasma cutter protection.

06-10-2014, 6:54 AM
I Googled Franzinator and that appears to be a similar design to what he built.

Are there smaller units that one can buy to accomplish the same thing? I'd build one of those, but... I don't have anywhere to put it. I guess the tampon thing worked pretty well, huh?

06-10-2014, 6:54 PM
I maintained the plasma cutters and they didn't show any moisture or rust in their individual small separators, so +1 for tampax. Rust was a problem in the school pneumatic lines due to high air demand and humidity.

(Welder who showed me that trick was highly experienced and an artist with stick and TIG. Said he learned it working shutdowns where time was money and it could be quicker to grab some metal and rags then wait on a dryer. He also taught me if you need to purge long lines of pipe etc you can swap an argon cylinder nut and nipple onto an oxygen or other high-pressure regulator and crank it open rather than maxing out a limited flowmeter. A large reg flows a shitload more than a flowmeter and there's no reason it wouldn't purge motorcycle tanks too.)

You could get something one of these dryers or make a big one out of pipe and fittings:


06-10-2014, 7:36 PM
The dessicant driers woork decent, but I still pulled water through them.......I drain off my compressor of water every day too.

My next step is a refrigerated drier, pricey, but in my case, the plasma cutter is more money.
With painting I wouldnt think that water is as big of a concern now that everyone is moving too water based paints, but I'm no painter.....

06-11-2014, 6:50 AM
I'd try one or a couple Motorguard or similar toilet paper filters next to your plasma cutter if it's that bad. They work well and are very quick (if you put a 1/4-turn shutoff valve before them so no dumpee da air line) to swap rolls of asswipe between jobs.

Their popularity with plasma cutter owners is because they hold a lot of water and the density of asswipe stops moisture passthrough unless saturated.

BTW ask in welding forums for where to get the best deal on plasma consumables for your particular machine. Some local welding suppliers are cool but others have drug dealer markups...