3M accuspray gun - first attempt was a FAIL, need advice.

I know, I should have asked before I started. But anyways, I need to spray clear gel with 0.015 metalflake. I armed myself with the new 3m accuspray gun and a 2mm nozzle. From my research on spraying flake, I needed to get the gel/flake mix to a mud like consistency, so I did. I hooked it all up, and set the pressure to 20psi (max recommended for that gun), and pulled the trigger. Nothing came out. Only air. I bumped up the pressure to 30 psi, no change. I went down to 10, no use. I tried adjusting the fan shape knob, and the flow control knob, no change. So then I went ahead and watered down my mix with more styrene, to get it real runny. Still nothing. I went ahead and cleaned out the gun, and tried spraying acetone through it, and it would not spray. Before I put the flake in it, I checked the gun by running water through it, and it worked fine. But now, it is being cranky. Any advice appreciated. Thanks

 

You need much larger tips for flake or it will plug up just as you described.

And that gun won't spray gel coat very well because the tip is much too small.

Depending on the exact flake, you need at least a 3mm tip, which they don't make for that gun.

Look on Amazon for a 3mm hvlp gun, or buy a 2.5mm and drill it out bigger. Less than $35 gets you a good 2.5mm spray gun.

You don't need to mix it up like mud, there is no right or wrong amount of flake. You add the amount that yields the look you desire.

And flake comes in many different shapes and sizes, with smaller flake you can get away with a smaller tip.

Don't add styrene, it turns yellow quickly once it's exposed to the sun.

 

well, I may have figured out the problem. When I pull the trigger, there are air bubbles going into the cup. Not good. Seems like I may have a bad nozzle. The tutorial I watched bud had a 1.8 and the flake would go fine through that. I will play around some more and post back.

 

Which accuspray gun did he have? The one with a pressurized pot will spray gel coat, the new version lacks that option. And was it the same size flake you were using?

Attach the link, a 1.8 tip is too small to do much of anything with gel coat unless you thin it a great deal, which isn't good.

 

Also, how big of an area are you trying to spray?

If the area is very small, a 1.8 might do it, but would be very slow. Just doing a boot stripe would seem like an eternity.

 

okay, I go everything to work out. I needed to thin it down a little more, with a little less flake. Then the stuff came out of the 2.0 really nice. I am doing just a spot repair on the gunnel cap on my boat, about 3 inches wide by 8 inches long. it did not turn yellow, however, if it did I would not care much since it is not the clear coat, just the gel holding the flake together. Even when I watered down the gel/flake mix with styrene it cured just fine in about an hour without yellowing. I think its not the styrene that causes yellowing, but acetone, if you use that for thinning. for the clear coats I didn't thin very much, and although being much thicker, it when through the 2.0 nozzle really well with good thickness. Thanks you @ondarvr for your advice, I am done this stage now and moving on to sanding and buffing!

 

It doesn't turn yellow when you mix it in, styrene turns yellow when exposed to UV light.

Acetone doesn't turn yellow, but can have its own issues.

Since you are doing such a small area the 2mm will get it done, but limit the thinning as much as possible.

The reason for a larger tip is to reduce or eliminate the need to thin the gel coat, plus speed up the job on larger surfaces.

Adding styrene doesn't stop it from curing, but it does compromise the physical properties of the gel coat. This includes water, UV, crack and flex resistance.

Adding 3% styrene will cause a slight increase in yellowing and may not show up short term in other areas. If people limited it to 3% it wouldn't be much of a problem. People tend to go overboard and add 15-20% or even more. This has a terrible impact on the physical properties.

For the next repair job look at the Duratec line of products, you don't need to thin them because they are formulated for this type of use.

 

The pressurized accuspray gun will push out just about anything. I just finished spraying a 18ft skiff plug with duratech base primer. Basically mud. If you have the standard hvlp gun & not the pressure pot gun, it will not like anything remotely thick.

 

Great thread, looking to start doing small to medium gel shooting myself in the UK, will have a good read over all of this!