Spray gun cleaning, what solvents

Terry NJ

Terry NJ

Well-known member
I got lazy last year and hung up the spray gun, partially full of paint. Now what do I do? Plus, I have some HVLP guns that need a good cleaning. Again, I need the name of a good solvent to break it all down. I have lacquer thinner, but this is too aged for that. Most of the paints are PPG shopline (if it makes any difference) that I've used in it. I've heard of Acetone and MEK. Thanks!
Terry
 
I suspect you are screwed. Maybe you could take it to a body shop and ask them if it is salvageable or a lost cause. Is the gun high valued or a cheap one? I almost had the same thing happen a few weeks ago. I sprayed some SPI high build primer and the spec sheet said do not leave in the gun for more than 30 minutes. I was done in 35 minutes and I barely got the paint out of the gun with lacquer thinner. I bet you don't do that again!
Rusty Nelson
 
if it is urethane and has gone hard all i can say is good luck.
if it is still soft gunwash / lacquer thinner should soften it and wash up. pull the whole gun apart and soak it in a can.
 
You guys use different terminology for paints from us but if the paint was a two part (paint and catalyst) one go and buy yourself a new gun. If it is what we call acrylic lacquer, soak it in gun wash or the same thinners you used when painting and flush thoroughly. Then, don't do it again! :)
 
Your best best in my opinion is some good old fashioned stinky carburetor cleaner.
take out in seals or it will eat them up. Dump everything in and leave it for a week or
so.
Then flush everything with lacquer thinner.
 
Try Methyl ethyl ketone. I found that I could remove paint that had dried in some of the paint brushes that paint had dried in. I think that you may be able to buy it at Lowes, Home Depot or paint stores. I filled a container with it and let anything that paint had dried in or on sit in it until it dissolved the dried paint. I used it on my Purdy brushes that my son used and didn't clean. Hope it works for you.
 
Terry, there are several brands of good quality spray gun cleaners that are made specifically for this purpose. Don't try chemicals made for cleaning carburetors or other generic solvents. We use a 3M spray gun specific product. They work very well at dissolving 2k primers & paints, so from my experiences the gun is savable.

The issue that makes guns repairable or not, is the soft parts (seals, o-rings, plastic cuts, etc.) availability. Many guns today are made to be 'throw-away' guns simply because the value of the labor to do thorough cleanings exceeds the value of a gun. Many spray guns are just like computers where the prices for new units is way less than what they were several years ago. Our spray gun of choice right now in the shop is a Sata 5500 which is under $1k new. Five+ years ago this was a $2,500 gun. It is on the edge as far as a throw-away gun. The DeVilbiss FinishLine gun is one of the guns we use for spraying primer, -and would be considered a very good hobbyist finish coat gun. The last I knew, these were in the $250 range new and are considered a throw-away gun meaning the clean-up time exceeds the value of the gun by the time the hours spent cleaning and costs of replacement parts are factored in. A Harbor Freight spray gun is honestly not worth the cost of the cleaner needed to clean it, so the answer to your question is yes you can save the gun but is it a value to do so.
 
Your lucky you don't live in California. Everything that worked
has been banned, and some replacements we have left just don't
work. Not trying to be a jerk here, but you committed the number
one sin in paint gun maintenance. Good suggestions from previous
post to try.
 
Last edited:
Methylene Chloride or Dichloromethane was what was sold not too many years ago as a gun cleaner but as was mentioned, a person may need a repair kit to replace the soft parts like seals & packings. I don't know if the stuff is even available anymore. It's same as the old carburetor cleaner. The gun would need to be completely disassembled to soak it any form of solvent and a person would likely have to chase all the fluid ports to get it working again.

Kleen Stip makes "Naked-Gun" gun cleaner that is marketed not to be the old stuff but I don't know what it is.

It may be cheaper to purchase a new gun depending on what a person wants or needs.
 
Last edited:
Thank you all for your help with this. Too many years ago, I hate to think of how many, I worked a little with MEK (Methyl Ethyl Ketone) and TCE (Tri Clor Ethane) and they became firmly locked in my mind as the two greatest solvents ever. Trouble is that they were so good that now I can't find them for sale anywhere. Like Chlordane, the world's greatest insecticide. Our favorite uncle with the striped pants has put the kibosh on its use. So now, Some of the restrictions are merely a state thing and some are federal. BTW, Yesterday, I went over to my local HF for a new $15 "Purple Gun" and the were all sold out. I believe that you cannot make a profit on that gun at $15 ( $9.00 ) and that it's heavily subsidized by the Chinese govt, in which case, they're losing on it as a "Loss Leader" GOOD!
Terry
 
Terry said:
Yesterday, I went over to my local HF for a new $15 "Purple Gun" and the were all sold out. I believe that you cannot make a profit on that gun at $15 ( $9.00 ) and that it's heavily subsidized by the Chinese govt, in which case, they're losing on it as a "Loss Leader" GOOD!
Terry
Click to expand...

Terry, many do not realize that using those cheap spray guns that cannot (-does not) atomize the paint very well actually costs more to use than if someone spent the money on a better quality gun and used less product. We just got another price increase on PPG's DCC9300 which is nearly $600.00 a gallon now wholesale. The hardener is almost $150.00 a quart, and solvents are up too. That makes Black single-stage urethane paint over $115.00 a sprayable quart. My Sata gun would likely spray the same coverage and mil thickness with 5 quarts to the Harbor Freights gun using 7 quarts. Doesn't take long to realize how a quality gun saves $$ in product usage, ...and then because it sprays the finish of the top-coat slicker, less labor is spent doing post-paint work such as colorsanding and buffing.
 
MEK is still available but a person has to know where to find it. It has been getting more expensive too, like everything else. It is the quintessential solvent for polyester resin also known as Butanone. It's around $25 a gallon from harware stores.

TCE is not so easy and the price is way out there at over $100 a gallon.

Not too many remember carbon tetrachloride but it was the best solvent to my knowledge. It was banned for any home use back in the 80s but like any chemical, it's still around for use in chemical formulation of other chemical products and propellants.
 
Last edited:
BRENT in 10-uh-C said:
Terry, many do not realize that using those cheap spray guns that cannot (-does not) atomize the paint very well actually costs more to use than if someone spent the money on a better quality gun and used less product. We just got another price increase on PPG's DCC9300 which is nearly $600.00 a gallon now wholesale. The hardener is almost $150.00 a quart, and solvents are up too. That makes single-stage urethane paint over $115.00 a sprayable quart. My Sata gun would likely spray the same coverage and mil thickness with 5 quarts to the Harbor Freights gun using 7 quarts. Doesn't take long to realize how a quality gun saves $$ in product usage, ...and then because it sprays the finish of the top-coat slicker, less labor is spent doing post-paint work such as colorsanding and buffing.
Click to expand...

You raise a good point that I never realized before. But then I'm not an real body man or a pro painter. I'm a hobbiest who occasionally paints cars! I never realized that one of the qualities of a great spray gun was that it used less paint. Now that I think about it, it makes sense, but how? Through better atomization? Is it directional? More of the paint gets onto the work and is not dissipated into the air? I've been using the $15 HF Purple gun and I can't say what's wrong with it, but they seem to be OK for a couple of primer applications and then and then they start messing up. I notice that my primer jobs are very uneven and require a lot of sanding to flatten out the surface. Sanding is one of the most tedious things you can do on a car and I don't like it at all. I've got a couple of old guns that are not of the HPLV type. The passages seem to be clear. Is there any point to using one of these? I don't want to invest big money at this time, in a SATA type gun, with maybe this job and possibly one more before I'm finished with painting forever. Thanks in advance!
Terry
 
rotorwrench said:
MEK is still available but a person has to know where to find it. It has been getting more expensive too, like everything else. It is the quintessential solvent for polyester resin also known as Butanone. It's around $25 a gallon from harware stores.

TCE is not so easy and the price is way out there at over $100 a gallon.

Not too many remember carbon tetrachloride but it was the best solvent to my knowledge. It was banned for any home use back in the 80s but like any chemical, it's still around for use in chemical formulation of other chemical products and propellants.
Click to expand...

I think I saw a "modified" version of MEK in Lowes a while ago. I liked the good old days when I had a coffee can of TCE (Covered) sitting on my bench (sigh) A long time ago. It was a great degreaser and it turned your hands white when you degreased some parts. All these bad news chemicals stink so badly because of their affinity for evaporation. Later on I worked in a shop where the machines had friction drive wheels that had to be kept clean from the oil and we sprayed Per Chlor Ethane onto the spinning wheels to keep them up to speed. With dozens of those slingers of the Per Chlor twirling around at hundreds of RPMS, you can imagine what the atmosphere was like.
Terry
 
My old siphon guns still work for me. One is high pressure low volume the other is standard. I only do my own work now days. The days of painting helicopters and components with the old Imron and Deltron urethane are long gone. I use the Best polyurethanes I can find now days but I don't have to do near as much as I used to. I still have a half gallon pressure pot somewhere but I rarely ever need it.

I'm careful to clean the gun as soon as I'm done. It's a lot easier and it only takes some lacquer thinner to get it clean for the next job. I've made the mistake of not cleaning soon enough and once was all it took to alter my procedure back to ASAP.
 
If youre buying the cheap guns at HF, just throw them out after one use.......

not worth the water and time to clean a roller cover! just buy a new one.
 
Terry said:
You raise a good point that I never realized before. But then I'm not an real body man or a pro painter. I'm a hobbiest who occasionally paints cars! I never realized that one of the qualities of a great spray gun was that it used less paint. Now that I think about it, it makes sense, but how? Through better atomization? Is it directional? More of the paint gets onto the work and is not dissipated into the air? I've been using the $15 HF Purple gun and I can't say what's wrong with it, but they seem to be OK for a couple of primer applications and then and then they start messing up. I notice that my primer jobs are very uneven and require a lot of sanding to flatten out the surface. Sanding is one of the most tedious things you can do on a car and I don't like it at all. I've got a couple of old guns that are not of the HPLV type. The passages seem to be clear. Is there any point to using one of these? I don't want to invest big money at this time, in a SATA type gun, with maybe this job and possibly one more before I'm finished with painting forever. Thanks in advance!
Terry
Click to expand...


The best shine comes from a flat surface. Flat as in the substrates, and flat with the outer payer of the finish coat. Let me ask you a couple of question for you to think about. Suppose you were to have two equal sized aquariums that you filled with round objects, -one with golf ball sized spheres, and one with balls the size of BBs. When both aquariums were complete fill to the rim, which aquarium would have the smoother or flatter surface? Most would agree it would be the aquarium filled with the BBs. Arguably, the aquarium with the BBs will have less voids (-trapped air and/or solvents) between the spheres which would allow the paint to shrink down and stabilize better. Additionally, there will be less colorsanding and buffing needed when the top-coat of paint's texture is only as rough as the BBs instead of the Golf Ball sized spheres.

So my point is a cheap spray gun typically can only atomize the paint down to a certain size however the top-quality guns have the precision to atomize the paint into much finer size of spheres where it lays down and creates a much finer surface. Since a much thinner MIL thickness is needed for adequate coverage when the paint is atomized finer, less product is used. Likewise, if the texture on the painted surface is much smoother, then less time and materials are used to sand and polish it to be flat. That is why it is a value to pay more for the better quality gun and use less product or post-paint labor rather than use a cheaper spray gun that costs more in materials and labor.
 
You must log in or register to reply here.
Back
Top