# small bumps when spraying



## jkpainter (Jun 3, 2007)

While spraying a clean primed door with water base semi-gloss, we ended up with lots of tiny bumps that look like pimples on parts of the door. Does any one know what causes that and how it can be prevented?


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## cole191919 (Jan 10, 2008)

Are you using an HVLP or airless?

If your using airless, if you have the pressure up too high it can give a finish like that. 

Also from what I understand, if you do not let a 5 gal. pail sit for a good period of time, the air pockets in the paint will not have a chance to settle and escape causing it to surface in your application. That is also given you are using a 5 gal


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## NEPS.US (Feb 6, 2008)

jkpainter said:


> While spraying a clean primed door with water base semi-gloss, we ended up with lots of tiny bumps that look like pimples on parts of the door. Does any one know what causes that and how it can be prevented?


Clean your gun and springs.... or rebuild it.


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## CobraCDN (Jan 8, 2008)

Be nice to see a picture... U sure they are bumps and not fisheyes? Is it a wood door or is it mdf or hardboard slabs?

Cheers


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## DeanV (Apr 18, 2007)

I always assume I missed some dust or something before I blame the paint, but another option is to look close and see if it is really small craters, where air bubbles popped. If this is wide spread on the doors, it could point to an issue with the defoamers in the painter.


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## YubaPaintPro (Mar 2, 2008)

Thanks DeanV! As a rep, I appreciate the lack of assumption.  I also agree w/ DeanV, it is likely tiny air bubbles that got trapped in the paint and found their way to the top before the film dried. Also could be defoamers.

Sand them out, turn your pressure down a bit. I'd like to think that if your using a enamel (oil/latex), that your using a small tip and you ought to able to turn your pressure down below 2500psi. Again, assuming airless.


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## OverSpray (Mar 13, 2009)

Had a problem similar to this while doing rental house,problem was found around all light switches,doors and any trim around kitchen/dinning room/den.After playing mr. CSI ( my brother is a chemist ) we discoverd the previous owner clean up before moving out using cleaners containg orange oil in them,wash down with mild solution of tsp and the problem went away.


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## jack pauhl (Nov 10, 2008)

jkpainter said:


> While spraying a clean primed door with water base semi-gloss, we ended up with lots of tiny bumps that look like pimples on parts of the door. Does any one know what causes that and how it can be prevented?


You primed this door or sprayed over factory primer? Spraying over factory primer sometimes will create these tiny bumps, depending on the paint used, they go away or they dont.


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## JCM (Jan 6, 2009)

jack pauhl said:


> You primed this door or sprayed over factory primer? Spraying over factory primer sometimes will create these tiny bumps, depending on the paint used, they go away or they dont.


Factory primer sucks or doesn't suck. spraying over factory primer will always create tiny bumps or it will never create these tiny bumps. No matter what paint you put on it will look great or bad just as long as it's good material or bad. I'm sorry JP but are you even talking?



> Originally Posted by *jkpainter*
> _While spraying a clean primed door with water base semi-gloss, we ended up with lots of tiny bumps that look like pimples on parts of the door. Does any one know what causes that and how it can be prevented?_


 Could you post up a pic of what you are talking about? It could be a number of things like what has been mentioned by the Real contractors here. Contamination, air, dirt, poor prep, pressures so on and so fourth.
A pic and description of process and material is needed to get to the bottom of your issue.


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## Wolfgang (Nov 16, 2008)

...I still get goosebumps when I spray.:whistling2:


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## WisePainter (Dec 27, 2008)

I have had the same problem in the past and couldn't figure it out. 
So in order to stop standing around burning time, we sanded and resprayed with no further issues.


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## DeanV (Apr 18, 2007)

The original post is over a year old guys.


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## Wolfgang (Nov 16, 2008)

DeanV said:


> The original post is over a year old guys.


 
DAMMIT!!!


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## slickshift (Apr 8, 2007)

1) Always check thread dates when a n00b replies
2) The answer to the OP is "Stop using the Wagner Frustration Spitters" and get a real sprayer




jkpainter said:


> While spraying a clean primed door with water base semi-gloss, we ended up with lots of tiny bumps that look like pimples on parts of the door. Does any one know what causes that and how it can be prevented?


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## Bender (Aug 10, 2008)

Slick, I dig your sig line:thumbsup:


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## slickshift (Apr 8, 2007)

Thanks


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## jack pauhl (Nov 10, 2008)

JCM said:


> Factory primer sucks or doesn't suck. spraying over factory primer will always create tiny bumps or it will never create these tiny bumps. No matter what paint you put on it will look great or bad just as long as it's good material or bad. I'm sorry JP but are you even talking?
> 
> 
> Could you post up a pic of what you are talking about? It could be a number of things like what has been mentioned by the Real contractors here. Contamination, air, dirt, poor prep, pressures so on and so fourth.
> A pic and description of process and material is needed to get to the bottom of your issue.


I dont get what you are trying to say. Too difficult to call because often you have no idea who makes the door for me to say it happens this particular door from this supplier. The builders I do work for get doors from 4 different suppliers. None of the 4 are the same. It's the primer that causes the bumps or bubbles that dont go away with some paints. You can create this by taking a wet rag to the door, all it takes is rewetting the factory primer.


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