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Tue Jul 31, 2012 7:54 am

I just sprayed some Summit Racing 2K HS Urethane Primer with a new Summit LVLP gun (can't tell any difference between it and a HVLP) with a 1.7 tip. The cfm of the compressor is unknown, but it has a 220v motor and a 2-piston upright pump- virtually identical to a 5hp-60gallon compressor I used to have. I had an inline gauge at the end of the gun showing approx 60 lbs with the trigger closed and 30 at wide open. It seemed to spray well, but left a lot of orange peel to be sanded out. I know theres no way to tell without being there and seeing it, but where should I start in trying to reduce the orange peel?

1)- The regulator at the tank is set at approx 80lbs for the other air tools I use, does it need to be turned up to 120 for full flow to the gun?

2) Does increasing the line pressure on the small regulator at the gun help reduce OP? I see on some old posts that a lot of people run hvlp guns at around 50+ lbs?

3) Does the air volume knob at the base of the gun have much effect on OP? Gun came with very poor instructions..

4) After this primer is sanded out the next coat will be House of Kolor KOII white sealer. Since it uses a reducer, with all else being equal on the gun settings would it likely be thinner and spray with less orange peel than the high build primer did? The KOII is not designed to be sanded, the tech sheets say to let it flash and topcoat within 2 hours...

5)When it comes time to topcoat, I have another new one of these guns with a 1.3 tip and also have an older Shape Finex HVLP with a 1.4 tip- I use PPG Concept and its so expensive I hate to use much of it experimenting on a piece of sheet metal trying to get gun settings right, is it feasible to get a quart of of a cheap shopline paint and use it to set up the gun, or might the consistency be too dis-similar from the Concept to tell anything?

Thanks, somewhat a novice, have only painted 2 cars and a Harley before this, although they turned out well enough that other people have asked me to paint for them :roll: - But the first one was painted with an old style siphon gun I can't seem to find now, the second one with a Sharpe hvlp about six years ago that I never got to spray without orange peel, and the Harley was painted entirely with old style touch up guns..

Tue Jul 31, 2012 1:01 pm

not too sure about lvlp guns. with hvlp your tip size for primer is spot on. for base you definently want to use the 1.3 tip. the peal in your primer is more than likely due to pressure being too low, or distance from the panel issue. depending on how the gun is set up, when spraying base and clear run it with everything wide open, fan, pressure, and needle. go get you a pressure guage with a regulator and put it on the end of your gun. make sure you dont have pressure spikes and drops while spraying, which is very important when spraying your base. you really need to find out what optimum pressure should be to spray with with that gun though. due to the nature of base coat the peal shouldnt be a problem. with the clear that is a whole nother story. however so long as you have enough material on the panel you can knock the peal out with a cut and buff after everything has dried.

Tue Jul 31, 2012 3:09 pm

after you spray your sealer, before the top coat window closes, spray a light base coat on it. let it sit over night. now, hit it with 800 wet, clean, re-base and clear over it.

what this does is kills the peel in the last coat of primer/sealer but still lets you get correct adhesion by spraying down the base and re sanding it.

it was a trick Schell59 told me, and worked killer.

Tue Jul 31, 2012 4:57 pm

yessir works the bomb...be carefull of drag marks and sand scratches even WITH 800,but even before that, make sure your sealer is laying flat..plus your base is wet and not laying dry as well....when your spraying your clear...your product itself can cause peel because of its make up and your gun too...a real gun with atomize way better than say a harbor freight or a summit knock off...a SATA or a Devillbiss is expensive for a reason...the nail it with needle sizes,air caps and transision...some novices do not research these areas and think the clear and color will lay the same at half the price for materials and the tools...

Wed Aug 01, 2012 7:00 am

I use an IWATA LVLP and set the inlet pressure around 16psi with the gun triggered. 30psi sounds too high to me... Too high a pressure will also give some peel.
An old trick I picked up when setting your gun up is to set your pattern from six inches away (from the surface), getting a six inch wide pattern with the finest overspray droplets possible (around the outer edges of the wet area). This gives a pretty good INITIAL setting and you can fine tune it to your liking from there.
LVLP guns can get away with lower volumes of air than HVLP, but it's still a good idea to use high-flow connections and fittings throughout your air line system. Much less chance of surging air pressure if the compressor is not up to par. Keep in mind, HVLP and LVLP guns were developed for bodyshops and professional painters. They will work in other settings, but still rely on an adequate, clean air supply.

schell '59 is right, good guns are expensive for a reason, cheapies are cheap for the same reason.
In my opinion, buying a good spray gun is like buying a good compressor, once you really get using it, you'll never regret the extra expense. It's tough to see someone lose a paint job over a cheap paint gun. Paint supplies cost way too much money to have to do the job over or be less than satisfied with the results.
The gun you buy once, screw up the paint and you're buying it again.

Wed Aug 01, 2012 2:51 pm

also make sure that your reducers and hardeners are good for the ambient temp when you are spraying.