How have I screwed up this primer?

[julianf]

To clarify -

Compressor to 3 stage
To belt pack (through known clean hose)
Which feeds both mask AND gun (gun hose is the old hose)

 

[Nick DV]

cheapy reg combo

https://www.ebay.co.uk/itm/Air-Pressure-Regulator-Gauge-Spray-Gun-In-Line-Water-Separator-Oil-Trap-Filter/264240044204?_trkparms=aid=1110001&algo=SPLICE.SIM&ao=1&asc=20200423095753&meid=e2e74cb1568440cdb4b9c67e220d6415&pid=101224&rk=5&rkt=5&mehot=none&sd=132408058403&itm=264240044204&pmt=0&noa=1&pg=2047675&_trksid=p2047675.c101224.m-1

I've a couple of these and found they work really well

 

[carbon]

oil from your compressor , would be my guess , separate oil separator and reg needed ,

see this earlier post

Air from the compressor is going through a 3 stage to a belt pack, with a small line from the belt to the gun.

Very unlikely for contamination to get past a 3 stage filter

 

[Munkul]

I just can't see how the job can still be dirty if I've painted it, then used enough paper and thinner to wipe away all of the failed layer of paint?

I mean if I've done enough wiping to remove a layer of paint, but there is still contaminants, I kind of have no hope!

I'm not really even saying there isn't. I mean somthing is going wrong. But my logic just does not work that I can managed to wipe away a whole layer of paint off a job, but still leave a problem chemical behind. On a previously sanded bit of metal.

I reckon it's got to be hose, or user error.

It's silicone! That's just what it does. It's a nightmare. Nothing like any other sort of contamination, it's totally invisible and very difficult to get rid of.

Test spray a fresh bit of metal and see if its contaminated surface, or if its contaminated paint/air.

Even the car manufacturers have this problem, and they just scrap the parts.

https://www.kcprofessional.co.uk/me...on_Guide_from_Kimberly-Clark_Professional.pdf

My bet would be something to do with your air line arrangement - make sure there's not a load of thread tape etc. Oil could still cause this problem.

Like I said earlier, sometimes you can get around silicon contaminate by locking it in with etch primer... if you're lucky...

 

[julianf]

I just put on another coat with a different air line to the gun.

No difference.

I photographed the job before and after the 2nd coat as then, I figure, I'll be able to see if the craters come back in the same places, pointing toward surface contamination, or different places, pointing toward product contamination.

I also drained the compressor just as I'd not done so in ages. Nothing to speak of.


This times arrangement -

Compressor
25mtr air line to garage
3stage (pressure reg at this point)
25mtr to air fed (clean)
Belt pack
25mtr to gun and small to mask

So we now have 75mtrs of line between the compressor and gun.


It's just a cheap gun, but I've used it on jobs before with no issue. Last job was the one that I mentioned a while back - hammerite with hammerite thinners. Gun was cleaned well after that, but could that be the issue?

Maybe I'll compare these two sets of photos and, if the craters have moved (ie product contamination) I'll see if I can use a different gun as another test.


One last thing - I didn't use any thinner at all on this mix. Just 100g of 29107 and 30g 29370


Thank you all for your replies so far. Much appreciated.

 

[Munkul]

HAMMERITE!!!!!!!!!!!!!!!

That's your problem right there. Hammerite has silicones in. Sorry mate, your gun is ruined... simple as.
You'll have to buy a new gun. Good job it wasn't an expensive one.

And don't ever spray hammerite ever again... you'll have contaminated everything around with spray mist.

Or, alternatively, ONLY spray hammerite, and you'll not have a problem

 

[mr haynes]

As per munkul above.
I only ever sprayed hammerite with my blower gun, primer gun only primer, paint gun only base/2k
Never used a silicone spray lube in workshop either for the very reasons already mentioned

 

[julianf]

Cool - so at least there is a solution. Im happy with that.

Its a real cheap gun - one of those £20 kit things from the usual suspects. Im pretty sure i have another one knocking about too thats never been used.

Forecast says rain, but its still sunny outside. My garage still has no roof, so this is important to me.

Ill check the forecast, and see if i cant run another coat with another gun and see what happens then.

Thanks again.

 

[julianf]

Cheapo gun #2 -

Never been used.

None of my other guns have the screw on the side, where the paint cup attatches.

I'm guessing Google will tell me what it's for, but anyone want to beat me to it? : )

Thanks again.

 

[julianf]

I'm assuming it's an hvlp, but, really, as you might be able to tell, I have no real idea.

I didn't even buy this one. Just acquired along the way.

Tip says 1.5

 

[carbon]

Possibly fan control

 

[Munkul]

I'd say fan control. Usually placed further back, that's all. Controls air pressure to the air nozzle directional ports and therefore fan width.

You'll have to clean the life out of the panel again, or you'll be left with silicone again. It does not want to come off! Toluene is one of the better solvents for this.

 

[julianf]

Two questions -

One coat has been on there since last night - wont that have set hard now?

Second - no chance of just misting over it again?

 

[julianf]

...i have stripped the paint. It was not fun.

My experience of paint has always been that ive not been able to fix previous issues by putting more paint over. I know it can be done, but my luck has not been good.

So, once again, i have bare metal... and it is about to rain here now, so i either have to move the compressor (so its not in the same place as i am painting indoors) or wait until later.

 

[Munkul]

you can sometimes get away with a few very light coats of primer. Essentially silicone removes surface tension of paint, so it wants to flow around, hence fish eyes. A few light coats can sufficiently cover over enough to get a full even coat on after drying... I've done this with etch primer before... but it doesn't always work... so I'd say you did the right thing.

 

[julianf]

Still no success. Starting to get sad now.

I spray, and then, as i watch, within seconds, the craters form from the flat paint layer.

Just the same as before, but with the previously unused gun. Really no difference.

There happened to be a plastering trowel close by so i hit the bottom of that. Exactly the same.


So, gun side of the 3 stage, ive now changed everything. Its got to be either technique, or mix contamination?

Im not even spraying in an area thats ever had hammerite near it.

 

[Al Strachan]

i used to get similar ish results until i fitted a filter (same red one as shown previously) to my gun. Also its quite damp here at the moment, and without a temp controlled garage and all the filtration i have, i wouldn't even attempt to spray 2k until the weather perked up.

You are going way beyond the levels of cleanliness and prep that i would and still not having success, its been said before, but i would improve your moisture traps at both ends, wait for a sunny and dry day then try again.

 

[julianf]

These are the syringes that I'm using to get the product out of the tin. I worried they may have some sort of lubricant on them, but the packet says they're for spinal / epidural use, so I'm guess they would have to be pretty clean for that?!

 

[keithski122]

Could be the cloths or thinners used for clean up.

 

[julianf]

Re temp -

Despite the forecast, it's been sunburn weather here all day today.

I'll order one of the little gun filters. I mean I'm getting to the point where I'm searching about for new things to change!