HVLP gun issue

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Forum topic by Robert posted 09-10-2021 08:53 PM 202 views 0 times favorited 2 replies Add to Favorites Watch
View Robert's profile


4731 posts in 2722 days

09-10-2021 08:53 PM

Its a Husky gun, 1.4 & 2.2 tips. I usually run around 15-20PSI.

Going to spray some oil based poly (Behr) and even though it says “don’t thin” I knew it was way to thick to spray.

So, I thinned it about 10% and when I sprayed using the 2.2 tip, the air was bubbling back up into the cup. No matter what I did with the adjustments, I could not get it to even spray. This gun has never been used. So, I dumped it, and ran some acetone through it – did the same thing.

Switched to the 1.4 tip, sprayed perfectly. Thinned poly 50/50 with naptha.

Any ideas?

-- Everything is a prototype thats why its one of a kind!!

2 replies so far

View bilyo's profile


1406 posts in 2344 days

#1 posted 09-11-2021 12:30 AM

First, I think that the 2.2mm tip is too large for what you are trying to spray. The 1.4mm tip should work just fine. For the air bubbling back into the cup, I think something is leaking inside the gun. Check everything for proper tightness and check all soft (plastic, rubber, etc.) seals.

View JAAune's profile


2034 posts in 3558 days

#2 posted 09-11-2021 12:52 AM

Air bubbles in the cup means your air pressure is somehow backing up into the fluid portion of the gun. Blocking the air holes in the cap could cause that. I suspect there was some blockage that you didn’t see which was removed in the process of changing to the 1.4 tip.

The larger 2.2 tip shouldn’t cause that problem if the 1.4 didn’t do so. 2.2 may be too large for the product but that would cause insufficient atomization rather than air in the cup. I suggest putting the 2.2 back on and seeing if the problem shows up again. Check your airflow without finish. You should get air out the air holes when the trigger is half-pulled and air out the fluid tip when the trigger is all the way back.

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