Hot Rods spray gun cross contamination

Question for the masses.

I am working on a side project for the wife and I have a question.
I am building the Viking table for the wife and I am getting ready to spray the clear. It's a clear urethane and it is thinned with mineral spirits.

My question is this. If I spray that through my dedicated automotive gun, will the mineral spirits contaminate the gun? Since it a petroleum based product, I am concerned that it may cause problems forever.

Thanks,

Root

 

Buy a cheapo gun from HF, you might like it for oddball jobs.

 

As long as you thoroughly clean the gun , it will be fine .

 

I don't see a problem as long as you completely disassemble the gun to clean it after the fact.

 

Not if you rinse the gun with lacquer thinner a couple of times...
I usually not my gun apart and clean it after every use so I've never had a problem, I know I've sprayed degreaser and paint stripper through my guns and never had any problems with them.

 

For a small project why not just use a Google d quality rattle can? I've rattle canned a few small things that came out really great....

 

Lacquer thinner is like the top of the food chain for solvents, it will clean up just fine.

 

Don't use your Iwata gun. If it were me, I would either buy the HF gun or use an old gun ( I have like 10 of them). I'd keep the clear coat gun far from anything that could Fup a nice paint job.

 

It’s a giant table. It’s 6’x9’, that’s why I have been leaning towards spraying. I brushed the bottom side and it has a lot of air bubbles. Plus, I hate brushing.

But, to keep it traditional it is 2”
Thick red oak and has breadboard ends with dowels and I built the legs out of 4”square tubing. All drawn in CAD by my buddy @NoSurf.

 

The HF purple gun is $9.95, plus tax, with a coupon.

Clean it before. Spray, then throw it away.

 

I have used my good gun for stuff like this lots of times. As mentioned, make sure you clean it good with thinner afterwards and you will be fine.

Or, buy a throwaway gun at HF as also mentioned.

 

I bought one of those piece of craps a while back….the think leaked like a sprinkler. Then the “anodized” coating wiped off with lacquer thinner. I know you get what you pay for, but I wasted $30 in gas driving back and forth.

 

Shouldn't be a problem. As long as it is cleaned and flushed well. My good gun has done old style enamel, poly varnish, urethane single stage, urethane clear, spar varnish etc. Still works fine and no fish eyes! That is the first symptom of contamination. Good cleaning prevents that.

 

I use urethane on yachts, both inside and out. I use foam brushes, and only the Red Tree brand. Don't continually go over the urethane, this will give the air bubbles, no more than 2 passes. Any bubbles on the first pass will disappear. I used to spray but have found that unless you are in a quality booth the foam brushes give a more than satisfactory finish. Don't use Chinese brushes, I have yet to find any that are any good.

 

For indoor or outdoor use? If outdoor make sure you use exterior or spar urethane.

From slowest to fastest, urethane can be thinned with mineral spirits, naptha, or lacquer thinner. Unless it's about 90 degrees where you're spraying, I'd avoid the spirits and go with naptha or lacquer thinner. Spirits dries so slow it'll drive you nuts and allow an extended time for dust or any other airborne stuff to settle and stick.

Whatever you use, be careful with the thinning. The usual amount is 4 to 6 ounces per gallon. Far less thinner than you'd use in automotive paint, and if you over thin it, it'll run like water.

My experience in spraying bare wood is that you need to get a good sealer coat on, let that dry, and sand before applying additional coats. The sealer coat will have what looks like a bunch of solvent pops bit it's actually air bubbles from the pores of the wood. Once it's sealed and sanded the subsequent coats will lay down smooth.

As far as the gun goes, just clean with lacquer thinner the same as with automotive paints and you'll be fine.

 

It would cost more to clean up than it's worth... lol

 

On projects like that I use my primer gun and as said clean it with lacquer thinner.

 

Properly cleaned there should be no contamination issues. If you are leaving contaminants in your gun when you clean it you will end up with issues regardless of switching products or not.

 

I had good luck with them. The first one I cleaned and thought “what a waste of time”. I did notice they have plastic nozzles though. The last few I just tossed and cleaned and saved the cups
I’ve only used them for primer and tractor matte paint though.

 

Just some random thoughts about brushing paint. Me to.
I did however discover that a quality brush matched to the products viscosity makes a world of difference. Some products say to stir rather than shake for the reason they do hold air. Temperature effects flash/dry times and that effects the risk of entrapment. A thinner product soaks in a void, a thicker one fills over it. Overloading the brush makes for a sloppy painter.
Depending on the surface, and the product, you could be spraying all day to apply what a brush or roller will do in almost less time for the thickness and without the waste.

 

All of mine are all metal but the cup and the seals.

I even have a 3M adapter for the Gen2 cup system for mine.

I have a few where I reamed out the tip to 2.2mm for heavier materials.

 

Um, they do ship these, cheap.

The only time I have had a lead is when something was not tight.

 

Heck, I must have gotten the economy economy model. I have one left. Going to take a look at it

 

Oh wait, I said nozzle I meant tip. My mistake.

 

I just checked the six that I have hanging up. They are all metal.

Weird.

 

Damn, now I wonder if I tossed the other ones with thinking about it. Have to find the one I still have and take a look

 

Maybe they have stepped-down to plastic to save money!

 

Maybe, I bought the first one about 4-5 years ago, then the other two a few years later. The first one had the plastic tip, never paid attention to the others. I’m pretty sure I have one left that I picked up a year or so back and never used, just need to locate it

And you’d be correct in assuming I have no organizational skills

 

Well, found the one I haven’t used, and it is metal, actually from the inside it looks brass colored.
Only plastic is the securing “nut”.
Dang, should have cleaned them and kept them.

 

My 91y.o. father told me that years ago when he worked building and repairing ambulances and hearses if thinner was in short supply they would use petrol (gas) to thin enamel for spraying. Same deal, just flush the gun with thinner before reusing.
I got dumped on a while back about using Vaselene (petroleum jelly) on the needle and pot seal after cleaning the gun and storing it for later use but have never had an issue with contamination. A quick spray of thinner through it before use to check for operation (which should be done anyway, even with a new gun) and away we go.