Nitrogen to Paint?

[Doug Krebs]

So I'm taking my normal morning dump and I'm flipping through the harbor freight catalog. Just browsing and see a couple different water traps for compressors.

I know people go through great lengths to get rid of the moisture in compressed air when they paint. Why not just hook up the gun to a nitrogen or CO2 bottle. I'm going to assume one big bottle would probably be enough to paint a car? Maybe it would cost $20 to rent one a month and have it filled?

Not painting anything any time soon, I was just sitting on the crapper and got to thinking :gigem:

[Graystroke]

I would think it would add more moisture when it is comming out of there at 1800psi and starts to freeze up. U would have to have some special reg. i wouldn't even know where you would start. a good electric fan drier is $500 and will do the job

[Doug Krebs]

I would think it would add more moisture when it is comming out of there at 1800psi and starts to freeze up. U would have to have some special reg. i wouldn't even know where you would start. a good electric fan drier is $500 and will do the job

Yeah but if just wanted to dick around painting something I don't want to spend $500 on a drier. I also don't think my compressor would be up to the task.

I agree with freezing up. It would probably need one of those hi flow regulators. How would it add moisture to the inside of the line?

[AggieTJ2007]

you would have to build some sort of heat exchanger out of coper tube so you don't freeze the paint

[Graystroke]

kinda what he said when you freeze the paint and then it hits the atmosphere it would suck moisture from the air.

[Doug Krebs]

ahh ok, I see what you're saying now.

Just wondering for those of you that have painted, how dry does the air have to be? Do you need a desicant filter?

I was thinking of building one of those "franzinator" deals by the compressor and running a small desicant filter by the gun.

If you've never heard of a "franzinator", it's basically a vertical 2ft long piece of pipe. The compressed air comes directly from pump into the middle of the pipe with a nozzle that directs the air towards the bottom. The air exits at the top and then is plumbed into the tank. There are all sorts of plans on the internet of these things and different theories about them.

I really just want to dick around in the future painting some small things. Maybe one day a car, but probably not with the compressor I have now.

[DRAGOONRANCH]

Since the co2 or nitrogen would be dry in the tank, then I would think that the gas coming out at 50-100 psi would not gather any moisture. The air compressor gets the moisture straight out of the air it brings in correct. The air coming out of the compressor is not cold enough to condense the moisture in the air correct?

[Doug Krebs]

Yeah, but what they are saying is when the cold/freezing paint hits the warmer atmostphere it's either going to form condensation in the air or when it hits the metal.

[DRAGOONRANCH]

I can see how the gas coming out at 1000+ psi would do it, but not at the pressure you would be painting with. I think it's doable, but getting enough flow may be hard.

[Sharpe]

Even if the gas coming out was only 10-20 PSI it is still colder than ****. Ever aired up tires with a CO2 tank? The regulator and air hose get colder than ****. Something tells me if this was a good idea someone would have done it already.

[DRAGOONRANCH]

nope, never really messed with the co2. what psi are you using coming out of the tank

[DRAGOONRANCH]

I am basing my assumptions on this situations on my use of oxygen tanks.

[Sharpe]

My experience with CO2 is limited to setting up a kegerator and helping air up tires on the trail. As long as pressure is being released I dont think it matter what the PSI is, it will still be hella cold. To weld aluminum with a MIG you need straight CO2 for the gas, which means you have to get a different regulator because an argon regulator will freeze up if you use it with CO2. MIGs use 30-40 PSI. It just the nature of the beast.

[Doug Krebs]

I can find info on it for air brushing, but the site said that only required about 1 cfm of air. I believe a normal paint gun needs roughly 10 cfm to operate well.

[Sharpe]

I've been shopping around for one and most need 10-15 CFM.

[Doug Krebs]

I've been shopping around for one and most need 10-15 CFM.

How good of a gun are you looking for? Are you actully good at painting?

I ran across a thread one day about a specific model that Harbor Freight sells. They had a 3 page write up about how to set it up, etc... Seems that some people thinks it's one of the best guns for under $500. I know I have the thread saved somewhere, I'll dig it up if you're interested.

I bought the gun a couple of months ago as it was on sale. I haven't used it yet as I really don't have anything to paint. I might mess around with it at christmas if I feel like it.

What do you have to paint? I could bring my gun over and we could mess around with it. I've never painted using a spray gun.

[Doug Krebs]

Hmm we use nitrogen at work to heat treat and to purge furnaces. I'm not sure what volume the regulator is though. I'll look at it on wednesday when I work next.

I'll hook up an air gun on a 50ft hose and see how much volume it will flow and how fast it freezes up if I have free time. Maybe I'll hook it up to the liquid port and shoot liquid nitrogen around. These kids are crazy!

[Sharpe]

~$300 or so. I have a bunch that I priced and spec'd typed up on a spreadsheet at home, the current leader is a DeVillbiss, I dont remember the model right off hand though. I am eventually going to paint my entire jeep and am going to do it 100% right and pimpish. Between now and then I'd like to paint pigpen first just for practice, and then maybe the crewcab. I've never painted anything before but I try to avoid buying cheap tools when it affects the end product.

[Doug Krebs]

I've never painted anything before but I try to avoid buying cheap tools when it affects the end product.

Thats what I'm getting at... I'm pretty sure we wouldn't be able to know the difference or get any benefit from an expensive gun. However, I'm not saying buy a 10 dollar gun that no one has experience with. It would be like me playing golf with a $3000 set of clubs vs. walmart clubs. I'm pretty sure I'd suck just as bad with the expensive ones.

Also, I don't expect to be able to do a high quality paint job. I would like to be able to paint well enough that it looks good from a couple feet away.

I'm sure fred or someone that has experience will come and school us.

[eight]

Yea just get the $10 gun, drain the water from your compressor, use a cheap drier, and shoot light coats. You should be able to see through the first coat. I like to use 3 coats if I want to do a decent job. For a good paint job, I use my check book. You know how long it takes to paint a crew cab?

[Doug Krebs]

Found the website... I have the 43430 gun.

Harbor Freigh HVLP (http://purplesagetradingpost.com/sumner/techinfo/HVLPspraygun.html)

[agjohn02]

10-15 cfm from an 80 cubic foot bottle. you do the math.

edit: maybe im thinking scuba. whats the big bottle 122 cf? still...

[Doug Krebs]

10-15 cfm from an 80 cubic foot bottle. you do the math.

edit: maybe im thinking scuba. whats the big bottle 122 cf? still...

Thats part of the problem I have no idea how long it takes to paint. The bottles we have at work are big, around 350cf I think. The bigger one's hold more pressure I believe.