Airbrushing with CO2?

i think i will be fine with free air, from a compressor. its been reliable for about 6 years now, about 2 hours weekly, sometimes more, sometimes less.

QUOTE: Originally posted by cmarks1965 I really like my CO2 setup, but am wondering if it could be causing some of my tip dry problems when I use acrylics. The gas is perfectly dry and compressed air isn't even with a moisture trap. Anybody else get tip dry with their CO2?

It isn't the CO2, it's the acrylic paint. Acrylic dries so ridiculously fast that virtually everyone gets tip dry when using it. I just keep a Q-tip moistened with alcohol or water handy and every time I sit the airbrush down I just wipe the tip off.

You can also add a couple of drops of acrylic retarder to your paint bottle / cup. That significantly slows down the drying time of acrylics and helps alleviate tip drying a little bit (not a lot, but a little bit).

Weigh the tank when filled, use the bathroom scale, and when it is getting about 20 pounds lighter then get it refilled. I have a 15-pound tank. It runs 37 pounds when full and 22 empty.

I really like my CO2 setup, but am wondering if it could be causing some of my tip dry problems when I use acrylics. The gas is perfectly dry and compressed air isn't even with a moisture trap. Anybody else get tip dry with their CO2?

QUOTE: Originally posted by MikeV QUOTE: Originally posted by Frank This pressure is pretty constant and the only drawback I've run into is the fact there's not much of a hint that you're running low on gas, hence my backup cylinders. Don't your gauges tell you what's left in the tank, or do you just have a single gauge for operating pressure? I love that story about the tank you found at work. Pennies from Heaven. Mike

Well, since CO2 is sold in 'pounds' and works at a fairly constant pressure, there's no accurate way to tell what's left. If I were using my SCUBA cylinders or for argument's sake, acetylene (NOT recommended!), the pressure drops as the supply gets depleted and you can read the gauge to see the lowering pressure in the cylinder. Since CO2 maintains it's pressure to the end, it's hard to tell what's left. That's why dual-stage regulators are found on oxygen or acetylene cylinders - the welder can adjust the pressure with the secondary (working pressure) gauge while the primary gauge can show the lowered pressure remaining. With CO2, it's 850 psi and that's it.

I still laugh about that day I found the 20 pounder. IIRC, I was angry my five pounders were empty and lamenting the fact I couldn't afford a bigger cylinder. What fun!

QUOTE: Originally posted by Frank This pressure is pretty constant and the only drawback I've run into is the fact there's not much of a hint that you're running low on gas, hence my backup cylinders.

Don't your gauges tell you what's left in the tank, or do you just have a single gauge for operating pressure?

I love that story about the tank you found at work. Pennies from Heaven.

Mike

Mike -
After my tour with the SCUBA cylinders, it was easy for me to choose CO2. Yes, CO2 is liquid in the cylinder and boils off at room temp to around 850 psi. This pressure is pretty constant and the only drawback I've run into is the fact there's not much of a hint that you're running low on gas, hence my backup cylinders.
As for the conversion, it was pretty straighforward and as long as the cylinder can pass the safety test, you're in. I found three old CO2 fire extinguishers in my parent's garage and had them all converted. I ended up giving two away to guys in our local club when I found the 20 pound cylider I currently use. As God is my witness, I drove to work, parked and right next to my car was the cylider, laying on the ground. Well, it took me all of three seconds to realize what it was and hump it into the trunk! Talk about pennies from Heaven...
The real problem with my SCUBA rig was the costs. Refills were around $5 but yearly inspections were $25 (x2) and the looks from the owner of the dive shop when I needed a refill in the Winter were classic. My old, steel cylinders are rated for 3000psi but they were typically filled to around 1800psi. That translates to about 80 cubic feet of air. I've yet to find a table to compare cubic feet versus pounds for industrial gases...

Thanks for the update Frank.

I was unaware of that fact.
I know what you mean about using a scuba tank. They have a lot more pressure than a CO2 tank but not near the running time.
I guess it's because CO2 is a liquid right?

Mike

I just posted a response to a similar query on rec.models.scale. You can indeed get a CO2 fire extinguisher converted for airbrush use. Take it to a welding supply house and they'll replace the valve on the top with a 'regular' CO2 valve for around $10. You will have to have the cylinder safety checked (once every five years for around $10-$15) but they''re generally rated at 1600 psi and the working pressure is around 850, as previously stated.

Just because it was a fire extinguisher doesn't mean it can't be used in another role. It held CO2 before and in the same quantity - five pounds worth. I have one at the supply house right now, getting safety checked. It's worked very well for me and I also wish I had it before I bought my small compressor. My SCUBA cylinders even got in the act but proved too expensive for powering the airbrushes.

Hope this helps.

QUOTE: Originally posted by sigman I have a lot of scrap fire extinguiser and I would like to inquire if the tank can be converted for CO2 and if it safe to use.

I kind of doubt it as most places would probably not want to fill it if it is not a certified CO2 tank. They do not want to be liable for filling it. CO2 tanks have to be hydro tested every so often and I doubt an extinguisher bottle would fit the category.
I could be wrong but I would check into it.
That would have to be a very thick, heavy material extinguisher bottle to handle the high pressure of CO2 anyhow. At room temperature the pressure in a CO2 tank is 853 psi!

Mike

QUOTE: Originally posted by sigman I have a lot of scrap fire extinguiser and I would like to inquire if the tank can be converted for CO2 and if it safe to use.

As long as 1) You can find the hardware to connect them to a regulator, and 2) You don't exceed the maximum pressure rating of the tank, I can't think of any reason that they couldn't safely be used. I don't know if there are any legal issues or not. If you are going to use CO2 in it, I would check with the places in your area that refill the bottles. If they don't feel it is safe and meets appropriate standards they won't refill it, so you may be going through the efforts for nothing.

I looked one of them here in our office, and the fittings would not be usable. The valve and nozzle are in a single assembly that screws into the tank itself. If yours are the same, that entire assembly would have to be replaced so basically all you would have would be an empty steel bottle. I suspect that you could lease a bottle, manifold, and regulator cheaper than you could buy everything to convert one of them. This one did have a label on it that said it was tested to 720 psi, however the normal operating pressure was 240 psi.

http://community.webshots.com/s/image1/1/21/79/40012179fcVNCd_ph.jpg

That's my CO2 rig with a single stage regulator

I have a lot of scrap fire extinguiser and I would like to inquire if the tank can be converted for CO2 and if it safe to use.

I have a lot of scrap fire extinguiser and I would like to inquire if the tank can be converted for CO2 and if it safe to use.

thanks Scott

QUOTE: Originally posted by Garry_Gnu i saw a CO2 tube used for airguns, it says 4,000 psi. it doesn't have a regulator. only a valve that lets the air out. if i use it on my airbrush, since no gauges tells how much pressure is coming out, would my airbrush go kaboom if i let out too much pressure? i'm using a canned air right now and it's very expensive.

If it's the little CO2 cartridges I'm familiar with, about the length of a finger and a little bit bigger in diameter, you'd run out of gas pretty quick. Quite a bit of pressure in them, but not much volume at all. And yes, you would need some sort of regulator. They have about enough volume at that pressure to get your airbrush about halfway to the next county.

There are a couple of inexpensive ways out though. First, Badger makes what they call a "Spare Tire Adapter". Basically just an adapter that lets their canned air valve fit the stem on a spare tire. The catch is that the tire has to be mounted, so you can't just use an inner tube (I tried that once years ago, it didn't work). The next alternative is to get an air tank from Sears or Lowes or someplace like that. You'll still need a regulator though, and those are about $20. Stop at a gas station and fill the tank and you are good to go until it runs down. They are usually rated at about 90 psi so you won't get a lot of volume, but still more than several cans of air.

In the long run your best bet is an airbrush compressor or a tank of CO2 or nitrogen. Either of those would require more of an initial investment but would pay off in the long run with convenience and efficiency. Keep an eye on EBay since they tend to show up there from time to time. If your local hobby shops have a bulletin board, post notes that you are interested in a compressor.

i saw a CO2 tube used for airguns, it says 4,000 psi. it doesn't have a regulator. only a valve that lets the air out. if i use it on my airbrush, since no gauges tells how much pressure is coming out, would my airbrush go kaboom if i let out too much pressure?

i'm using a canned air right now and it's very expensive.

Wow! I just remembered that I have a CO2 tank in the basement left over from my aquarium days. I had no idea that it could be used for airbrushing. I've got to go find that thing. Thanks. -Lee

I would agree with Greg that for modeling it would last a long time. Some T-shirt artists use a 20 lb CO2 tank and it lasts about 6-8 hours at 45-50 psi. The only negative is that you can run out of CO2 in the middle of a project unless you have a spare or never let it get that low. The gauges can also freeze if sprayed a long time but I doubt that would be a problem with modeling as they don't require that much paint and time of spraying. In the long run a compressor is cheaper....possibly, as it all depends on how much you use the airbrush.

Mike

I use a C02 tank for airbrushing and I must say that I wish I had do it a long time ago before purchacing a compressor. I purchased a 30 lb tank at my local Carbon Dioxide Sales dealer for only $150.00(less than average hobby compresors in my area). The company set me up with the nessessary equipment such as the tank and line gauge and regulator; heck they even filled it for free too! There are many size tanks available depending on how much spraying you anticipate doing. A 30lb tank will hold enough compressed air to airbrush 15 to 20 1/72nd models before refilling for me. The air is clean and dry(no moisture trap needed), easy to regulate and best of all, it's completely silent with no eletricaly powered parts. Refills in my area for a 30lb tank costs me approx. $16.00 and its takes me around 2 years to use up a full tank...(IF) I'm really airbrushing alot. FSM did several articles and features on "Powering your Airbrush" covering the C02 tank option, thats how I came to use one today!