Ot car but still might help someone, delete if necessary . What causes these pits in 2k high build primer. Was a scuff and shoot, sanded to original paint and primed. Started with 320 wet then 600 wet. Can’t seem to sand them out, you can’t feel them with your fingers and only see them at certain angles. Will base clear cover them? Thanks. Sent from my iPhone using H.A.M.B.
Those are going to show thru paint and clear. Is it one area or the entire car ? Contamination localized on the panel or in the air supply. Not enough flow out, wrong reducer, old Hardner, sprayed too dry, too hot. Block that down and shoot another coat of primer.
My guess is either too hot of a reducer or you didn't put down enough material for it to flow. Just my .02 (and even that may be overpriced)
Did the car have surface rust on it before sanding? That sure looks like you painted over sanded surface rust that etched the metal, leaving low spots. If so, start block sanding till they are gone. If you are lucky the primer will stick to the pits, if not well it's going to bubble. If you can see it in the primer you will for sure see it in the final shiny paint.
There was 1 repaint on the car, didnt see any rust. Its only on a few spots on the car. Using turbine system with new primer slow reducer & slow hardner.
I need a 1.8 tip to shoot high build 2k brand marhydeI use 1.3 for base/clears and 1.5 for enamels. I might use 1.3 for epoxy primer that's really cut with reducer for a seal coat. I'd guess the tip was too small but I'm not familiar with a turbo rig Do you have a larger tip for that turbo rig?
Go back to sanding with 150 then when they are gone work to finer grades , finer grades too early tend to roll over the primer rather than cut it level . If you rub through ,as I suspect you will ,reprime with a 1.8 tip and lay it on wet. Then start again sanding 150 to cut level then work up to finer paper. Any imperfections in the primer will be mirrored or magnified in the top coat.
spraying a light mist of dark colored paint over the surface will help you see the low spots when your sanding. i would block that out with 180 dry then spray another couple coats of primer on those spots then wet sand.
I have 1.0 1.4 and 1.8 tip. Guess Ill have to resand the spots and reprime- resand. It sucks that they are so hard to see, you have to be at just the right angle and have the sun just right to see the bad spots Was hoping I could get away with it but guess not.
My 2 cents...........I agree with most of said above. Yes 1.8-2.0 on tip size for high build, and a number of things that could have caused it, with one of the possibilities/probabiliies being contaminated surface prior to painting. Waxes and silicons from common detailing sprays such as Maguires, etc., left on surfaces are very difficult to remove. Lots of threads here about the silicon nightmares. If the problem you have was in fact caused by surface contamination prior to priming, then you probably don't want to risk adding topcoats over it and possibly looking at a failure down the road. Depends on what you're building, but if you're adding high dollar base/clear or other topcoats, I'd sand that infected areas off entirely, not just smooth, and reclean then reshoot the 2k. You may also want to think about a sealer coat before the topcoats. If it's on a 20 year old Honda your fixing for the grandaughter's DD, then don't worry about it at all. A few other things: when you do sand the primer, use a guide coat light spray. small imperfections that are almost impossible to see and feel will jump out at you! You can get it a paint supply shops or any of the auto parts stores. Spraying it heavy will clog your sandpapers, and you'll be surprised how much a very light coat will contrast against the primer when you start sanding. The PPG rep at the Goodguys show told me the best thing to do to remove silicon is an aggresive wash with Dawn dishwashing soap and water, small areas at a time, and discarding paper towels after drying small areas to avoid spreading the silicons to other areas. Do this before the solvent wax and grease remover. Ask me why I was asking them!! The more I paint, the less I know it seems.......any painting gurus feel free to correct me.
Forgot one thing.....your pitting could be from solvent popping. If the temps were cold when you sprayed the primer, and didn't wait a longer than normal time between the coats to compensate for the slower evaporation, you may have trapped in solvents that hadn't evaporated enough before you added additional coats. When that happens, the solvents will blow little holes thru the added coats trying to escape!
Some times old hardner does this or if you let the primer sit to long after you activate it will look good when sprayed but will form bumps or lumps? It will bite you in the ass sooner or later. Also no one asked if you had a really good dryer at least 40 feet from the air source and plumbed properly, or was your air line ever used without a dryer. Moisture bubbles will form later, they only way to tell is to sand to bear metal. You don't want to take a chance on it when your talking about $1K in materials why take a chance. My drier is 80 feet from the compressor and has a drip leg before the dryer, I put a new hose on it and never use it for anything else. I seen hand prints show on cars that others have painted from where they pushed it in the shop before priming. Good Luck
Assuming that moisture and air dryers were not an issue with the use of a turbine sprayer. Can that be ruled out?
Looks like oil or silicone is contaminating the metal and screwing up your primer. It will show through and it needs sanded off and wiped down with some H.D. Wax remover cleaning solvent. In some places the pits look like deep rust pits or pits from harsh sand blasting. Needs more sanding and thick high build primer. Not a fun procedure. Sent from my iPad using H.A.M.B.
I bet there was still wax on the car when I started sanding, I just washed it then started sanding. Didnt use wax grease remover till right before I sprayed primer. Going to sand it back down tomorrow. Thanks guys.
I would bet it is the tip size. High build will orange peel like the surface of the moon when too small a tip is used. You should be using a guide coat as mentioned previously, regardless of the condition of the primer, when you are sanding so you know where your highs and lows are. Relying on finding them with your bare eyes is going to result in missing stuff that will show up when you start to paint. Also make sure you take your paint somewhere that can shake it up for you right before you are going to use it. The talc settles out like crazy in high build and it is almost impossible to get it properly mixed by stirring alone so every successive batch of primer you mix up to spray gets thicker and thicker as you finally get the talc mixed in from the bottom of the can.
Most turbine sprayers produce heated air supplied to the spray gun. If the heated air was warm enough to accelerate the catalyst/ hardner reaction it can produce a "solvent pop " type effect as the film cures too fast for gas from the catalytic reaction to escape. You might have to remove most or all of the primer and then reprime. Possibly, a good non sanding primer/ sealer with at least 2 coats or 1.5-2.0 mils film build, might keep the pits from showing through.
UPDATE. Resanded with 180 re primed using 2.0 tip , 320 wet. Think that did it. Now just have to redo the other bad spots. Thanks guys. Sent from my iPhone using H.A.M.B.
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