I recently bought a moisture trap for my compressor and tried painting while it was raining outside. I still get a paint blob after a few hours of painting. What's the deal with this? the moisture still formed after where the trap was installed.
That's interesting -- I had a moisture filter/trap that fit right on the compressor and it worked fine and I never had a problem with water in my paint. I now use a compressor with a 2.5 gal. tank and the trap is on a hose that is about 10 feet long. I never see any moisture at all in the trap when using the tank compressor -- most of the moisture will condense in the tank.
I don't know what kind of paint is being used but if it is acrylic it has a tendency to dry in the airbrush if you let it set too long. Some older type airbrushes have clogging problems with acrylics due to the design of the nozzle. I had this "blobbing" problem with my Badger 150 and acrylic paint. I got a new airbrush with the cone type nozzle and the problem went away. If you have to let the brush sit for a while with paint in it it's a good idea to submerge the tip in a bowl of water to help keep the paint from setting up.
Actually, a trap works better if it is a little ways from the compressor. That is, have a little bit of line between the compressor and the trap. A section of metal pipe is ideal. The air has to cool in order for the water to condense, so the cooler the air entering the trap the better. If the trap is right on the compressor the air may still be too hot, especially if it is a tankless compressor or one with a very small tank.
=== Nothing better than redundancy, I have a water/moisture filter on the first hose that leads out of the compressor and a second filter (Paasche) about a foot from the airbrush itself, second hose - all together about 12 feet of hose.. Have had this rig for the past 15 plus years and have yet to find any water blobs spattering on my models. Water blobs are really a pain in the rectum ("ass" for y'all on the west coast). I have an old, very old, Penncrest diaphragm compressor that I inherited when my Dad passed away back in 1977. He'd had it for about 10 years before he passed on. It's a little cantankerous and has to be either kicked or jolted and turned on and off a few times before it starts to work. But hey, if it works, it works and why spend money for a new one. I guess I keep it mostly for sentimental reasons. Reminds me of him, he was quite a guy, and my best role model (no pun intended).
However, if you want to spend a few more bucks, get yourself a canister of compressed Co2 , somewhat like the canister that dispense soft drink found in most restaurants. There are a few members of the modeling club I belong to that have this type of rig and to date, they all say that they don't even have to think of moisture/water. The only problem I see there is having to get the canister refilled after several models.
Depending on compressor/moisture trap, many require occasional draining. Those intended for a regular tanked type compressor and attached at the tank shouldn't need this. But, the inline filters that fit your airbrush hose, definitely need an occasional draining by opening the thumbscrew. I do this every time I pause painting for a minute. It may not drain anything every time, but I figure every time it does it's a splatter I saved from happening. If condensation is particularly bad that day, in a long session I may even reverse the hose on the compressor, lay it flat, and let it blow clean the hose between the compressor and filter.
Filters are also directional, be sure it's installed properly or it does little more than reduce air flow. If it's an inline filter, it should be close to airbrush end of hose, back just far enough to be out of the way.
Painting when it's raining more than a quick shower or just before/after a rain or wet snow isn't the best. Odds are high that the issue isn't your trap failing, more that you're sucking more moisture out of the damp air than it can remove. If your doing the garage/porch/outdoor type painting, there's not a lot you can do to overcome a crappy day. Indoors you can however control the room a bit with a dehumidifier. Takes a bit to have a drying effect, but on a cooler day a space heater can do the same if you're careful not to kick up too much dust with it. Doing this with a heater actually takes a bit of trial/error since temperature in the room can affect the condensation. And, the McDonalds "hot coffee" type idiot warning: Turn off the heater before painting, 1500watt heat element in heater + aerosolized paint thinner = possible big boom.
The design of these filters is to keep up with condensation created by the compression in the system. They don't do much to actually dry wet air. There's an item called a tank dryer used in some industrial applications that can do that at prohibitive costs, and filters help some, but it's not really their intent to dehumidify. Mild humidity they do ok, but bad humidity you need to dry the air going into the compressor to not get some moisture coming out.
You state "paint blob", moisture does look much like that, but a close look can usually tell it's water splatter rather than paint. Especially once dry you can see a puddle was there from the flow lines, but there's no dried paint puddle. If it is actually paint, there's a lot of factors to consider. Mix ratio, proper type of thinner, air pressure, poor brush cleaning, sedimentation in the paint cup, impurities in mixed paint, all seals and washers in place, etc etc.
Honestly, I think for a short time I used more brake fluid to strip paint than paint to paint parts trying to figure out why this or that happened with my airbrush when I got it. Been using one for years now, still keep a tub of brake fluid and some latex gloves up on the shelf for when *it happens. Rest assured that it'll never be some odd little detail piece that never gets seen, when it happens it will always be the topmost, frontmost part that will most display your error on the finished model and most likely on your final finishing coat. I'm in a valley with 2 rivers within a mile,
3 lakes within 5, and lots of wetlands nearby, it's humid here quite often, I spend a lot of time "preparing the air" before I even turn on the compressor. I never post here, not really into all the military building stuff that's prominent here, but damn, since it's too damp here today to even try airbrushing anything but little bits I could as easily brush so far today, and I'm feeling too damned lazy for everything else, figured I'd share the pain.
Where is your compressor located? Is it in the same room as you work in. Or is it in a remote location. If your air compressor is in a cooler location, say a cold garage and you are pumping air into a warm basement, the lines will condensate moisture as the air travels from the cold air into the warm house. A moisture trap should be mounted as close to end of the line as possible to do the most good. My recommendation is purge your whole system with isopropal alcohol. Drain down your air tank if equiped, pour in about a cup of alcohol, fire up the compressor and immediately open up the line at the far end, hopefully you are able to have that end outside. Remember NO SMOKING or OPEN FLAMES!!! This will flush out the water already trapped in the system. If your compressor is drawing cold air, you will want to do this a couple times a year and also purge/drain the system at least weekly. If you don't have an air tank, pour alcohol into the line at the compressor end, Hookup the line and blow the line clear. You may have to do this twice. The problem may not be water, it could be oil, either way this should help solve your problem. Not knowing the specifics it is the best advice I can give.
The Badger 155 is an excellent airbrush and should be able to handle just about any type of paint. Can you tell if your blobs are due to droplets of water or lumps of paint? A good filter/trap should be able to handle the job coming straight off of the small compressor. If its not efficient you might need to do as others have suggested and add a bit of hose between it and the compressor or even better add a second filter. If you are using the color cup you should periodically flush it and the airbrush. Another thing -- I have found that Tamiya acrylics can be problematic -- when exposed to air they have a tendency to gel and clump at times.
Usually when it starts spurting out funny sounds i remove the hose and typically it will spray a fine mist of water through the hose. So, yes, it is a paintblob caused by water mixing within the paint.
DO NOT PUT BRAKE FLUID THROUGH YOUR AIRBRUSH. I keep a tub handy at the paint table to fix errors as in soaking the part for a bit in it and using qtips and a soft toothbrush to scrub the paint off the plastic followed by soap and water wash. While it'll strip even many year old paint, it works fast on still tacky paint. It may be safe to put through your airbrush, has to be less caustic than some paints I've used, but I'd never do so myself nor suggest it, and there's no reason. Big point of the brake fluid mention was just that you've really got to be as prepared to fix an error as it is easy to make one.
There's very few paints I can use straight from the jar. My Badger is old enough they didn't stamp model on it, and I've long misplaced the manual, but it's similar to one of the 200 models and works like new. I paint with everything enamel, acrylic, nail polish thinned with acetone, auto paints, etc. Some it's just a few drops, but most I do thin. The exception being testors metalizers and some auto paint I get from a shop that does custom rattle cans but will sell me a one off 2 oz. bottle from their mixed paints which are already thinned for the rattle can. This however truly is a "what works for you" thing. Beyond just flow through the airbrush, different work habits, light spray, heavy spray, etc. make a difference. I may actually thin different for different coats of paint, thinner for mist coats, thicker for wet coats. Check for a water in oil reaction by mixing a few drops of paint, but most acrylics thin fine with alcohol. That said, head/needle size matters, a large head can pass thicker paint, a smaller head needs thinner paint. Air pressure matters, more pressure can pass heavier paint. Lower pressures, smaller head, thinner paint. How thin, there's tons of factors that go into that, but I heard someone once say the consistency of whole milk as a base. I usually find that just a touch thin, but it's a good reference point. I hear a lot of folks say they use Future acrylic straight from the bottle, I have to thin it myself or the flow pulsates badly and it tends to plug the head and start to spatter.
As for spare hose. If it's a bolt on type filter, it does go on the compressor, but the inline filters actually require you cut your pretty new braided hose and insert at that point.
I'm kind of thinking you just picked a bad day to paint, too humid. I'd still suggest eventually getting an inline filter. As someone else stated, on a tankless compressor, the air is still hot at that point it hits the filter. As it cools going down the air hose, moisture can still form. I've got a diaphram compressor, tankless of course. I used to run a filter at the compressor, and one inline. I now just run the inline and notice little difference other than a bit better air pressure as long as I keep the inline filter drained.