Airbrush-rengöring

Efter trehundrafuttifjorte airbrush-session med krånglande spruta googlade jag och hittade följande eminenta sida där Don i detalj går igenom hur man ska rengöra sin spruta och varför den beter sig som den gör https://sites.google.com/site/donsairbrushtips/

Jag frågade Don om jag fick kopiera texten för att inte glömma bort den, så här är den nu med Dons benägna tillstånd:

For me, the most important rule of cleaning is: Don’t put it off.   Dried paint is a lot harder to remove.

A lot of people will tell you that all that is needed to clean an airbrush is to flush it out with an appropriate thinner until it sprays clear.  My experience is that this doesn’t always work.   Sometimes I would find the needle stuck the next time I went to use the brush.  I suspect a little paint leaks inside the needle bearing and drys.  So, I always remove the needle and wipe it with a little thinner.  This only takes a minute, and it solves the stuck needle problem.  I also use an old paint brush to clean the front surface of the nozzle.

I keep a special bottle of thinner for cleaning, and pour a small amount in a glass cup for use.  When I’m done, the excess goes back in the bottle.  By the next cleaning, most of any pigment has sunk to the bottom.  As a last step in cleaning, I always spray a little really clean thinner.

I usually go ahead and  remove the head and wipe out the body and tip with thinner too.  It’s very easy to do on the 155, it just takes a couple minutes more, and I’m sure of having a clean brush. You can use an inter-dental brush for this, or I’ve found that a pipe cleaner fits nicely in the front and bottom openings in the body of the 155, and does a good job.  A pipe cleaner can leave little bits of fuzz, so after using one, I squirt a little thinner through the brush with an eye dropper to wash out any stray fibers.  I also use a pipe cleaner to clean the paint cup spout.

One way to clean the tip is to take the corner of a paper towel and roll it into a point.  Then dip it in thinner and poke it in the large end of the tip and twist until you can see a bit of it on the small end. I learned this on one of the forums.

If you are using a water based cleaner, it might be easier to insert the towel dry and then add the cleaner.  Water tends to soften the towel a lot.

To hold the tip for cleaning, I modified a wooden clothes pin by cutting it off and filing a little groove next to the ends.  Using it, I can easily pick up the tip from the bench and hold it securely. It eliminates a lot of fumbling.

Before re-installing the tip, I lightly rub the opening in the airbrush body that the tip fits against with a small piece of bees wax.  It’s just a little insurance to guarantee a good seal and avoid bubbles in the cup.

Some airbrush parts have very fine threads.  Be careful not to cross thread them.  If your airbrush is the type with a tiny screw-in nozzle, be very careful not to over-tighten it.  In fact, if you have the tiny screw-in nozzle, it might be better to just leave it in place.

Make sure the trigger is fully in place before trying to run a needle through it. When I insert the needle into the body, I hold it loosely.  That way, if I miss the hole, the point won’t be damaged. I push the needle in until I can feel it bump against the nozzle.  There should be some drag going through the needle bearing. You don’t want to push too hard or you may distort or split the tip of the nozzle.  I tighten the needle chuck and work the trigger to see that it feels right.  For me, the needle is the first thing out and the last thing in.

As a final touch, I turn the brush upside down, put a little clean thinner in the paint supply hole and shoot it out.  And that’s all I ever do.  I’ve read that some folks regularly disassemble their brushes and soak them in cleaning solutions and some even buy ultrasonic cleaners.  I personally have never seen a need for this.

Cleaning doesn’t have to be a hassle.  It’s just a matter of figuring out where the paint goes and finding the easiest way to get rid of it.  If it’s a through passage and the solvent is strong enough, aggressive flushing might do.  I’ve found that a pumping action with an eyedropper works pretty well.  If it’s a blind passage, like behind the cup, a quick swab with a tiny brush or pipe cleaner might be needed.  Each of my airbrushes has its own quirks, and I alter the process to fit.  A quick inspection with a magnifier and strong light source will show if it’s good enough.

Back Flushing

Back flushing means holding something like your finger or a paper towel over the nozzle of the airbrush while pressing down and pulling back slightly on the trigger.  This forces air back through the tip and into the paint cup, causing bubbles.  It is commonly recommended as part of the cleaning process.  Supposedly, it breaks paint free and helps to wash it out.  But here’s how I figure. Yes, it will cause bubbles in the paint cup.  But, in the narrow passageway leading to the nozzle, all you’re going to get is dry air blowing through.  To me, this does not seem like a  useful thing to do.  Anyway, I’ve tried it and I can’t see where it makes any difference, so I don’t do it.  I feel like I get better results with a pumping action from an eyedropper in the paint supply port of a siphon fed airbrush, or the cup of a gravity fed brush.  But, try it yourself and see what you think.  I do sometimes back flush to mix paint and thinner in the cup just before painting though.

Please note:  Since I first wrote this section, I’ve come to realize a value of back flushing that I had not considered earlier.  In most airbrushes, there is a narrow channel between the needle seal and the internal paint chamber.  This channel can collect paint.  By back flushing during cleaning, some solvent could be forced into this space and help keep it clear.

If the shape of your airbrush nozzle makes it difficult to back flush because it has a crown or forked design, try holding the rubber bulb from an eyedropper over it.

Airbrush Lube

When I bought the brush, I also bought some store brand airbrush lube and applied it to all the moving parts.  After some time, I noticed that the trigger action was a bit stiff.  I found that the lube had gotten sort of gummy.  I suspect it was nothing but glycerin with a little food coloring.  So I cleaned everything and put a tiny bit of sewing machine oil on all the metal parts that rub together.  I usually don’t lube the needle because I decided that lubing Teflon was kind of redundant.  The trigger movement has felt fine ever since.

Ammonia

Ammonia will dissolve dried acrylic paint.  But, it also attacks chrome.  However, a lot of people use a window cleaner, like Windex, that contains ammonia to clean their airbrushes after spraying acrylic paint.  Apparently, you can get away with this because the amount of ammonia is small.  But, I would always flush with clean water after using it.

Explosion risk

I clean with lacquer thinner.  And, I used to shoot into a large plastic jug with a 1/4 inch hole in the side, like the one shown on the right.  I had an old mask filter on top to catch the spray. But, it occurred to me that filling a jug full of such a flammable mist might not be a good idea.  So I did a test.  Instead of the filter, I put a sheet of Kleenex over the top of the jug and secured it with a rubber band.   Then I filled the airbrush cup about half full of lacquer thinner and sprayed it in the little hole. I took the jug outside and held a flame from a long butane lighter next to the hole.  There was a WOOMPH, and the tissue blew apart and caught on fire.  Before I could put it out, it partially melted the top of the jug.  I repeated the test with mineral spirits, and nothing happened.  It wouldn’t ignite.  If I had done this with lacquer thinner and a tight fitting filter, I believe the jug might have exploded.  And it wouldn’t have to be a flame.  A spark from static electricity could also set it off.

So I switched to cleaning with mineral spirits, and was doing just fine with Testors enamels.  But, after practicing with some blue paint that I had decanted from a spray can, and cleaning the airbrush with mineral spirits, I shot a bit of lacquer thinner just to check.  The spray came out blue, real blue.  And, I had even swabbed out he body and tip.  But, it obviously didn’t get everything. Besides, I don’t think mineral spirits will work very well on DullCote or Floquil.  So, I got to thinking; how can I go back to cleaning with lacquer thinner without making a potential bomb?

Here are the precautions needed to prevent an explosion:

Keep the percentage concentration of flammable vapor below the LEL (Lower Explosive Limit).
Don’t allow vapors to collect in a confined space.
Prevent ignition sources like static electricity.

So here’s what I have come up with:

Note: I am not recommending that anybody copy this.
It’s just to show what I did.

I had this piece of copper tubing laying around.  It’s 12 inches long and 1/4 inch outside diameter.  On the end, I attached a short piece of 1/4 inch I.D. rubber gas line.  The rubber makes a nice seal to the nozzle of the airbrush.  The can is an empty coffee can.

When I used my old cleaning jug with the hole in the side, there was always a fine mist that would fill the jug and drift right through the filter.
With this setup, the copper tubing causes much of this mist to condense, and liquid lacquer thinner drips out the bottom into the can.  The tubing gets cold from the expanding air.  It works like a still, and there is less mist drifting around to ignite.  Of course, there is still some vapor, but I keep a fan running to disperse it plus the can sits next to an open window, so I don’t see how it could ever reach LEL.   Also, since everything is metal, there is less chance of a static spark.  And, even if it did ignite, there would be a burst of flame, but at least it couldn’t explode.  It’s not very fancy, but I think it works OK for me. I added some weight in the bottom to make it less likely to tip over.  Even if it did, it will never be full enough to spill much.  When I’m done, I set the can outside for a while.  It doesn’t take very long for the small amount of thinner to evaporate.

Of course, if you are using water based paints and thinner, the jug would work fine.

Postscript

If you have a Sotar or one of the Badger Renegade airbrushes, or any other brush with a tiny tip, here is something you should read.  A member known as Wingman_kz wrote a response to a cleaning question in this thread on the Fine Scale airbrushing forum and I think he did an excellent job.

I’ve been using interdental brushes like the one shown below.  But, I wanted something with more reach.  I had this needle that came with an inkjet refill kit.  So, I took some pliers and pulled the brush out of one of the handles and mounted it in the end of the needle with some hot melt glue.  It works great.  The needle is .047″ in diameter, which is smaller than the Badger needles, so it will go anywhere the Badger needle goes.  I can replace the brush by re-heating the end of the needle.

I like these brushes better than the commercial airbrush cleaning brushes, because the bristles are softer.

Step by Step

I’ve added a step by step pictorial of how I clean the 155.  You can click here to see it.

DANGER!! DANGER!!

I got an e-mail from a fellow who said a friend of his suggested using gasoline to clean his airbrush.

PLEASE DON’T DO THIS.    Gasoline belongs in fuel tanks.  Lacquer thinner is bad enough.

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