Primer sprays like sand???

[timmycharger]

I have a current thread on the progress of my bodywork, I listed it below as it has the most recent pictures and its a pain to re post the same pics. We sprayed some Primer the other night and had some interesting results:

http://www.dodgecharger.com/forum/index.php/topic,111466.25.html

This past Sunday, we sprayed the underside of the panels, the primer went on smooth as glass and looks great. We ran out of activator so we had to stop.

The other night, we started the top side. The prep was exactly the same, all panels wiped down with PPG wax/grease remover, then wiped with a tacky rag. We mixed the primer as per instructions, its a 5 Star Extreme urethane primer, when used as a sealer, its mixed 4 parts primer, 1 part activator, 2 parts reducer.  We did use a new can of reducer and I believe it was the same as before, it was definitely the same brand.  We used the same activator brand and part number as on Sunday.

We tested the gun on the clear plastic of the booth, got a nice spray pattern and everything looked great when sprayed on cardboard. When he sprayed the hood, it didnt look like it was covering very well, but we figured it was just the first coat.  On to the Valance panel, it went on like glass, as it did on the hinges and bolts. The fender was so so, some went on smooth, but then it started to do weird things in some areas.  In some areas, the primer looks as though it was dry spraying, tiny balls of paint everywhere leaving the fender with tiger stripes.  Nothing changed with the gun or how he held the gun, i was watching him the whole time.  I cant understand why on Sunday the backside of the panel was perfect, but on the front side, not so much. I thought it was due to the body filler but the doors didnt have any and they looked the worst.  We used a cheap harbor freight gun to shoot the primer on Sunday, cleaned it thoroughly when done. We used the same gun the other night, but to rule it out, I had another Harbor Freight gun that gave same results, we then went to a 1.5 tip finish gun that we had which we sprayed color last year with excellent results, while it sprayed better, same crap.

I did some searching and found an old thread about someone using this product having similar problems and people suggested a bigger tip, but if 1.6 worked on Sunday, not sure why it works on some panels and not others.  The good news is that I will be blocking the entire car and sanding most of this off, but It doesnt seem right to me. Luckily on the inside of the panels its perfect, where we will be spraying blue next week.   The old thread I found is below:

http://autobodystore.com/forum/archive/index.php/t-2523.html?s=eba090b507ddca0c70aaf326b816fd62

[Pete in NH]

I'm not familiar with the primer you are using but, if it's a high build type the 1.5-1.6 tips may be too small.  High build primers usually use something like a 1.8 tip or bigger. From your description it sounds like too much air and not enough fluid. Also, the reducer may have been too fast for the shop temperature or the gun was too far away  from the surface being primed.

Those low cost Harbor Freight guns are also know to be very inconsistent, sometimes they work fine, the next time they don't. Also, a lot of low cost Chinese guns are full of oils and other types of corrosion preventives that can clog things up internally and give inconstant results until  they are broken down and cleaned very well.  I use an old Binks syphon gun for primer and its always worked well.

[jaak]

I'm not familiar with the primer you are using but, if it's a high build type the 1.5-1.6 tips may be too small.  High build primers usually use something like a 1.8 tip or bigger. From your description it sounds like too much air and not enough fluid. Also, the reducer may have been too fast for the shop temperature or the gun was too far away  from the surface being primed.

Agreed. Especially if you are using a Polyester Primer... you need a large tip for it. I bought a cheap gun (new was 20 bucks) with a 2.0 tip, and still had to thin it about 10% to get it to lay down smoothly. 2k urethane primers, I have a gun with a 1.8 tip I use for that.

Jason

[Canadian1968]

Well you said it was a urathane primer , so anything from 1.8 to 1.5 will be fine especially if mixed as a sealer . Your tip size is not the problem . I would suggest, wrong reducer or hardner? , wrong mixing ratio, wrong gun setup. Contamination, will not give the problems you are explaining .

Did you notice if the primer/ sealer seemed to kick off faster than normal ? Are you using any accelerator at all?? Your temperature conditions will hav to be pretty extreme at the same time using the in correct reducer at the time ( fast reducer super hot temp)

A clogged tip/ gun could give the same result but you should notice this right away. You should have full coverage in one coat . If you are not getting a nice even fill coat with one coat and correct hand speed , you simply are not getting enough fluid flow . Pull apart the gun and clean it out .

[timmycharger]

Well you said it was a urathane primer , so anything from 1.8 to 1.5 will be fine especially if mixed as a sealer . Your tip size is not the problem . I would suggest, wrong reducer or hardner? , wrong mixing ratio, wrong gun setup. Contamination, will not give the problems you are explaining .

Did you notice if the primer/ sealer seemed to kick off faster than normal ? Are you using any accelerator at all?? Your temperature conditions will hav to be pretty extreme at the same time using the in correct reducer at the time ( fast reducer super hot temp)

A clogged tip/ gun could give the same result but you should notice this right away. You should have full coverage in one coat . If you are not getting a nice even fill coat with one coat and correct hand speed , you simply are not getting enough fluid flow . Pull apart the gun and clean it out .

It was relatively warm in the booth when painting, I wish I checked the actual temp, Id guess close to 80. No accelerator used, Im using the recommended activator that's on the can of the primer. Im using the reducer the guy at the paint shop gave me for the project, its a medium reducer, Omni MR186. The same stuff I used last Sunday. It may have been slightly cooler on Sunday when we did the inside panels. We tried 3 fresh guns, all same result, good spray patterns.

[hemi-hampton]

Are you spraying this primer as a primer or as a sealer? That would determine your tip size. If mixing as a high build primer with 4:1 ratio then you would want a 1.8-2.0 tip. If mixing as a thin watery sealer at 4:1:2 ratio then you could use a 1.2-1.6 tip. Just my  LEON.

[timmycharger]

Are you spraying this primer as a primer or as a sealer? That would determine your tip size. If mixing as a high build primer with 4:1 ratio then you would want a 1.8-2.0 tip. If mixing as a thin watery sealer at 4:1:2 ratio then you could use a 1.2-1.6 tip. Just my  LEON.

Im using the product as a sealer, mixing it 4:1:2, very thin and watery, not sure if the tip is the issue as he sprayed the backside of the panels last Sunday flawlessly.

[hemi-hampton]

Do you have a filter in Gun, sounds like filter could be getting clogged. If not I would have to be there in person to see whats going on to figure out solution. LEON.

[Canadian1968]

Do you have a filter in Gun, sounds like filter could be getting clogged. If not I would have to be there in person to see whats going on to figure out solution. LEON.

A lot of those cheaper guns will come with a screen that fits right into the top of the gun, as one more filter before the fluid passes threw the gun. These are pretty useless and clog up very easy!!! Throw it away if your still using it !!

Also another thought. What cup system are you using ?? Are you jus using the metal cup that comes with the gun or do you have 3m or norton style plastic cup system If just using metal cup make sure your vent hole is not plugged on the lid !!!

[timmycharger]

Do you have a filter in Gun, sounds like filter could be getting clogged. If not I would have to be there in person to see whats going on to figure out solution. LEON.

A lot of those cheaper guns will come with a screen that fits right into the top of the gun, as one more filter before the fluid passes threw the gun. These are pretty useless and clog up very easy!!! Throw it away if your still using it !!

Also another thought. What cup system are you using ?? Are you jus using the metal cup that comes with the gun or do you have 3m or norton style plastic cup system If just using metal cup make sure your vent hole is not plugged on the lid !!!

Yup, the guns we used did have that little plastic filter, I thought it was a bit overkill since I used a screen when pouring the primer into the cup. Im using the plastic type cup vs. the metal one.