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Spray Gun Adjustments?


jer7440
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Hey, I was wondering what to adjust on my spray gun to reduce the orange peel that I am getting. Here are a few details:

1- This is my spray gun. sray gun I know...very low end, but it's what I have to work with.

2- I am using Behlens stringed instrument lacquer and thinner.

3- I have been spraying at about 35 psi.

4- I have tried changing my finish mix... first I sprayed the lacquer straight out of the can (like the directions said), then I tried mixing 1/3 thinner 2/3 lacquer. The thinned mix seemed a little better, but still not great.

I have spent a ton of time trying to get this level, and that's fine, but I have 2 small sand throughs that need to be re sprayed and I don't want to start over with the major leveling if I don't have to. And it would just be nice to understand how to best set up my spray gun :D

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My experience, which is limited, is that with a low end gun like that you are going to get peel.

Couple of quesions 35 psi at the gun or the tank?

What diamter hose an fittings?

I only use automotive euros so I cant tell you with the lacquer. I know old school painters used to spray a wet lacquer coat last to make it flow.

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http://www.harborfreight.com/cpi/ctaf/Disp...temnumber=92126

this is mine and I run it at 35-45psi. Depends on were in the paint stage I'm at, I start with a 50/50 for almost all the coats. I know Drak posted a long while ago the exact way he does it. For me this worked fine. minimal orange peel, and after I level sand I add a bit more thinner to the mix and shoot a few coats, this usually need almost no sanding to get it nice and smooth.

try adjusting the air supply valve at the bottom, and shoot on scrap until you get it nice and even. Most of the tmie that people have problems with peel is that they are too far away from the pice painted or moove too fast leaving an almost dry coat along the way.

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I actually shoot at about 25 psi myself, and 12-15 for some bursting procedures (not always).

Sometimes I shoot at 30-35, but not very often.

There are no hard and fast rules, but there are tips and discoveries along the way...

Taking for granted you have your air mixture and product feed valves basically correct, a good way to see where you're at with your 'mix' is that if it takes 35 psi to even get it to come out of the gun, it's thick, too thick for me anyway.

The thinner your mix, the lower psi it takes to get it out of the gun at all, so you can use that as sort of a barometer as to how thick your mix really is.

If the gun will shoot the mix at 15 psi, your mix certainly is not too thick...you get the idea...

And another thing, people call all sorts of things 'orange peel' when a lot of times it's something else.

Shooting at a high pressure like 35 and shooting too close can result in 'spray wave', which is not orange peel.

It seems that every time somebody has a problem with shooting their lacquer finish, it gets blamed on orange peel, when in fact, several different things can occur, so part of the problem is actually identifying properly what the problem is in the first place.

The most common reasons one would get orange peel:

1. Air mixture too high (it's drying before it even hits the target)

2. Shooting from too far away (it's drying before it even hits the target)

3. Moving the gun too fast (it's drying before it even hits the target)

4. Fast speed thinner is being used (it's drying before it even hits the target)

5. Mix is too thick to spray and flow smoothly (it's a constipated mix)

6. The air relief hole on top of the can is clogged (it's a constipated mix)

7. No retarder being used (helps flowout)

I didn't look at your link to see if you have a bottom feeder or top feeder, so don't know there...

But many other things can happen too...blushing, spray wave, too thick a coat applied (usually resulting in runs), dissimilar products used together or over top of each other (odd reactions), people thinking that when their finish dries, it's supposed to be real shiny, etc...

Under the right conditions, a dry finish can be shiny, but it's not mandatory, and it doesn't mean something is wrong if your sprayed finish isn't real shiny.

Some people attribute a perfectly fine but dulled finish to orange peel, which is a false assumption.

Using retarder or a slow speed thinner will usually result in a dry shiny finish, but using retarder/slow thinners is a whole different chapter.

I always use a tiny bit, or just buy a medium or slow thinner, which does the same thing...

Tons of people don't even know there are different speed thinners out there, that they're all the same, which is a false belief, and changing to a slower thinner can sometimes cure a lot of dry finish problems.

Using a slow speed thinner is the exact same thing as using retarder as an additive, it's just already done for you, and you have to really LOOK for medium and slow speed thinners, most places don't carry them as a rule, you have to ask around for them.

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Thanks Drak and Maiden69. I am one of those who didn't know that thinner came in differents speeds. I will have to check around for a slower thinner. Does the can indicate the speed of the thinner? I never looked real close at the can I have right now. I just figured thinner was thinner. Do you accomplish a similar result by using a thinner mix, ie. more thinner and less lacquer?

I am currently using a top loader gun...so even if the air is disconnected, I still get paint if I pull the trigger. This makes it kind of hard to judge my mix by my air pressure. The 35 psi number was just something I read somewhere, or somebody told me to try. I will have to try cranking that down. I was also thinking about trying a bottom feeding jam gun. I was contemplating some bursting and I don't think my current gun is up to the job.

I'm pretty sure what I am seeing is orange peel. The finish dries and it is bumpy or almost pebbly feeling...like the peel of an orange.

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You gun should be good for bursting too. But a small dedicated one could be better. All you need to do is adjust the paint supply needle and air accordingly. What Drak means about it flowing is if you are shooting and it takes a lot of psi to get the paint flowing smooth out of the gun, then it is too thick. thin it 50 50 set the gun to 25 and try to spray. Some time I keep the gun pressure at 35 (per instructions) and then just adjust the air supply valve in the bottom. If your mix is too thin and you use high psi it will flow too much and be a bit hard to control runs. as far as I know, and by my little experience I have had no problem with the thinned down solution.

As of bottom feeders, I don't like them. I got one and I hate that everytime i finish there is a few oz left in the bottle. Mine is not a jam one, but a regular gun. Here are both.

DSC03634.jpg

From the small one i have painted nitro, automotive metallics and pearls, the big one just 2K clear.

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