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Primer going on rough- Eko prime

Posted: Sunday, October 23, 2011 2:21 PM Quote
I am putting eko-prime on gel coated fiberglass and aluminum parts in preparation for top coating with eko-poly.

Using a Devilbiss Finishline 3 gun, adequate air by Stewart System standards, paint booth temp about 75 degrees, humidity is ambient (or a little higher due to damp paint booth floors) for Anchorage.

I am spraying the primer filtered but unthinned.

I think this might be a gun set up problem vs a product problem but I would appreciate any help you might have.

The primer is drying with a fairly rough texture- maybe about like a cheap formica countertop as far as depth goes but unlike a piece of formica this isn't smooth when you run your hand over it. It sands out fine with 320 grit but it doesn't seem like I should have to resand every piece after I spray...

Maybe related- for open areas do you shoot with the fan control wide open? also, I have the fluid control knob open about 2 turns right now.

Thanks
Posted: Sunday, October 23, 2011 7:48 PM Quote
OK simple fix,

Dilute the EkoPrime 10% with distilled water, Get the gun closer, lay down a satin wet coat that's just glossy enough that you can start to see the reflection of the paint gun while you spray.

Also a quick correction. The air requirements for the paint gun are set by the gun manufacture. To best figure out how to use your paint gun you should first read the gun manufactures directions and understand what each control on the paint gun does. Google information about spray gun set up and spray pattern testing and spray gun technique. Hang some butcher paper in the paint booth and run through some spray pattern tests to find out what gun setting works best for your gun and air supply.

The biggest issues I have seen are related to lack of air (CFM not PSI) and holding the gun too far away from the surface.

If you are not close up to the surface being painted I gaurentee you'll have a dry, rough, orange peel, finish with poor coverage. The Finishline III paint gun likes to be right about 5-6" from the surface in most situations.  It should be about a 9" fan pattern at that distance. You need to make at least a 60% overlap to reduce the possibility of tiger striping.

I don't normally run the fan control all the way open. The fan control after about 1/2 of a turn open from all the way closed does not make much difference in the size of the fan. What it's doing when you open it more is trying to adjust the fan from being heavy paint in the center of the fan to more paint out towards the end of the fan.

I'll shoot a few test patterns to find out what works best for the paint gun and air system I'm painting with. Each gun will be different and the same gun used with different air sources will act differently. Once I know what the ideal paint and air mixture is for that gun I'll back out the fluid nozzle a bit for the first few coats eventually ending back up at the ideal setting for the last coat of paint. I vary my speed and distance from the surface to adjust how much paint I'm laying down.

I suggest spending a few minutes watching YouTube videos of Professionals painting to learn some of the techniques they use. Also don't expect perfection the first time you pick up a paint gun. Like anything it takes a bit of practice and you have to screw up a bit before you nail down a technique that works for you.

Again I can't stress enough that you should not learn how to paint or practice painting on airplane parts. Get some scrap material to paint or use poster board. Nothing worse that having to sand and sand and re-sand on parts that you spent months building. Learn how to paint on stuff you can throw away.




Jason
Posted: Monday, December 5, 2011 11:39 AM Quote
One more thing I can add that will help some builders it to use a larger needle/nozzle with the primers especially if you are using the EkoPoxy 2 part primer.

Switching to a 1.4 or 1.5 tip can help give you a smoother finish.


Jason