Little paint help please.

[Ronw435]

I painted one of my fenders yesterday and this developed after the clear was on. There was nothing in the base coat that I saw but this showed up after the clear was on. I gave the coats the recommended time between recoats. I gave it about 8-9 minutes on the first base, 12 minutes on the second. I also gave the same amount to the clear as was the specifications of the paint. The paint is a Matrix MPB-LV base. I used a MR 870 reducer.
I am wondering if this is solvent popping? Or do you think there was something on the fender? I took the fender down to metal. wiped it down with lacquer thinner. Tack ragged it then shot it. The base went on nice and I never saw anything in the base after it was done.

Any suggestions?

Thanks for your help
Ron

[NEWFISHER]

"Took the fender to bare metal and shot it with base"

Did you shoot a sealer and the prime the fender before the base?

You might ask mods to move this to the paint forum....you will get some good advise over there too

Here: http://67-72chevytrucks.com/vboard/f...splay.php?f=16

[BigDan3131]

[QUOTE=NEWFISHER;6885179]"Took the fender to bare metal and shot it with base"

Did you shoot a sealer and the prime the fender before the base?


Those things need to be done first, if you did were you touching it barehanded or tack it after the base flashed off?

[Ronw435]

Yes I wiped down the fender with lacquer thinner then sprayed a high build primer, I sanded the primer, lacquer cleaned the primer, but I did not tack the fender after base had flashed. Guess maybe I should have done that.

Thanks for the reply's.

Ron

[Ronw435]

I painted one of my fenders yesterday and this developed after the clear was on. There was nothing in the base coat that I saw but this showed up after the clear was on. I gave the coats the recommended time between recoats. I gave it about 8-9 minutes on the first base, 12 minutes on the second. I also gave the same amount to the clear as was the specifications of the paint. The paint is a Matrix MPB-LV base. I used a MR 870 reducer.
I am wondering if this is solvent popping? Or do you think there was something on the fender?

I took the fender down to metal. wiped it down with lacquer thinner. Put two coats of high build urethane primer. Sanded the primer. Wiped down with lacquer thinner, Tack ragged it then shot it. The base went on nice and I never saw anything in the base after it was done.

Thanks for any help you can give.

Ron

[MP&C]

Ron, you don't necessarily have to tack between flash coats. If there's no trash in the paint leave it alone and apply your next coat.. The more you fiddle with something that doesn't need it, the more chance of stirring up dust, adding impurities, etc.

Were you painting this in a paint booth? Your flash times also consider air flow, which helps to outgas. If this was done in a home made booth or air flow was otherwise inadequate, flash times need to be increased from mfr's recommendation.

Why are you cleaning with lacquer thinner? It flashes much too quickly to insure all the impurities have been floated to the surface.. Hence the Wax & Grease removers are much slower at evaporation. They are intended to be used in steps. Apply with a clean rag, allow it to set long enough to float impurities to the surface but not before it has a chance to dry/flash off. Because of the need to wipe prior to the W&G remover drying, I only work a small area at a time, less than a 2' x 2' area. Then wipe dry with a different clean rag. I normally do a minimum of two of these cleaning "sessions" prior painting. It's cheap insurance.

For some reason my gut tells me you used some of the cheap lacquer thinner as your cleaner. These 5 - 6 dollar gallon cans are nothing more than recycled solvents, and who knows what are in there. Could be a source of your issue. Quality thinner should be closer to $20 per gallon. Regardless, it shouldn't be used as a final panel preclean.

Solvent pop is more prevalent with inadequate flash times, and you would likely see it more widespread than the localized area you show there. It also usually shows craters where the solvent escaped and left a hole in the finish. Just because of how the defect is localized in a "cluster", I'm more inclined to believe it is an impurity that got left behind..

[Ronw435]

Thanks Robert for your reply. I am not using a spray booth just my garage.
I blew the garage out a couple times with a leaf blower. Swept the floors good and when I sprayed I had all doors and windows closed as I live in N. Texas and the wind seems to blow all the time.

I was using the lacquer thinner from Home Depot. Your probably right about it being recycled. Kleen brand I believe. I will look into getting the wax and grease remover instead of the lacquer thinner. I was just curious why it didn't show up with just the base on? I am not looking for a show quality product as I will be using this as a DD. About 7000 miles a year. I am retired so I will not be going to work everyday. I am afraid that I would end up in jail if I tried to do a show quality job (which I am sure I am not capable of) and someone idiot opened their door into it or ran a shopping cart into it.....lol. I just want a nice looking paint job. Everything else looks good on the fender except that one spot. I plan on buffing the entire truck when done.

Let me ask you this Robert, how much more time should I give between coats when not using a booth? What is the longest you can go without having to re-sand between coats?

Again thanks for the reply Robert.
Ron

[MP&C]

Most of your manufacturers will have suggested flash times, assuming that the product is being used in a professional booth with adequate flow for said product. When the mfr has the suggested times for water born paints, those times are also assuming that the professional booth is set up with additional air flow for said product. Many will also give flash times per various temps in a baking environment, or additional times for lower temps. I doubt that they have any suggestions for what you are asking, so I'll give some generic "clues" and it would be up to you to adapt those to your particular painting environment. I am far from an authority on the paint you used, or any for that matter. But MOST basecoat paints are flashed and ready for recoat when the finish is no longer shiny and has dulled out. For Clearcoat, I use the times as a guideline, and check a test spot that is painted at the end of the spray session for a string pull test.. You'll find when clearcoat is real wet, your fingertip will just slide around in the sprayout. Too wet for next coat. Next stage of drying is that it has dried some more, but when you pull your finger away from the panel, you see strings that pull with it. Still too wet for next coat, but just barely. Next is that test spray is sticky, but finger pulls away with no strings present. Now you're ready for the next coat. Again, this "test" is done with a test panel or somewhere on the vehicle where fingerprints don't cause issue like a masked off window, and the test area should be one of the last areas sprayed. And again, this is a generalization of when the product has flashed. The process for the exact product you used may be different, so check the product data sheet, or call the toll free number on the can and ask their tech line. THEY are the authority on their product.. The longest you can go without re-sanding is referred to as your re-coat window. Check the data sheet or ask the tech line.

For pre-clean products, the only ones I have used are RM900 PreKleano, House of Kolor KC10, and Finish Pro 6000. I have used these products with good results except for once. Did a quick wipe and let it dry, I didn't do a final wipe before drying. What this did in essence was to float all the impurities to the surface, where they stayed. When I sprayed the base coat on top of that, I had a nice line of fish eye that looked exactly like the wipe pattern. So remember the Karate Kid's wax on - wax off. Use a clean lint free rag to wipe an area about 1 to 2' square. (wax on) Let it sit for about 30 seconds. (if it dries before you can wipe it off, use a smaller area or use more solvent) Then use a different clean lint free rag to wipe it dry, and before it dries on it's own (wax off). Move to the next area with a slight overlap. keep rotating the fold of your rags to insure the rag is clean where it touches the panel, switch to new rags when you run out of clean areas, when totally complete then repeat the process again (with new clean rags). As a home hobbyist one gallon of preclean will last your lifetime. Used correctly, it will insure that you don't waste hundreds if not thousands of dollars in paint materials in painting defects. I can't speak to any other pre-clean products, as this is all I have used. But I'm sure others on here can speak to the success they have experienced with other products. (Not sure about what O'Reilly carries)

[Low Elco]

I use the Dupont wax and grease remover. The main truck is not to leave it wet on the surface, like Robert said. Just keep wiping till it's all dry. I usually have a wet towel in one hand and a dry one in the other.

Also, another trick if you're basing is to shoot a light to medium "scratch" coat of base, just enough to see how it's gonna go. If that fisheyes, wetsand out the bad spot with 600, clean up, and try it again. Go over every thing after this first coat and check. If it's good, you should be good to go.

Good Luck!

[chrismoore701]

Did you ever use wax and grease remover or Prepsolve? Just a thought

[Ronw435]

Thanks a lot guys I really do appreciate the information. I will apply your techniques and see what kind of results I get. I am happy with the way the fender looks except for the little imperfection in the picture. I will definitely do the Wax and grease remover this next time. I hope the Kleen-Strip brand works out ok. I will let you know the results. Again thanks for your help it is greatly appreciated.

Ron

[Tinkermc]

I would sand and repaint

[hugger6933]

Sand the area around the problem with say 800 grit. The problem spot is as big as a fist say? Well then sand you a spot around it about four times that and blow on a little paint on the spot first, next coat come out a little more in all directions. On the last coat you ought to be able to bring the gun out to the end of the sanded area[that you had sanded with 600 or 800 grit]. Now I got ahead of myself [like I do sometimes] after sanding the "blend "or "spot"area with the heavier grit sand the rest of the fender with 1,000 grit paper and then your good to go. after you have blown the paint in the spot after it has tacked now it is important not to get in a big hurry here as a lot of us do when we have a small thing to paint we try to get it done quicker and just don't give enough flash times for the stuff to do right and that will lead to a RUN for the impatient.OK,where was I, oh, after the spot has been painted clear the whole panel and your back in business. A lot of the trucks/cars I build from wrecks I have to blend the paint into the adjacent panel and the best place to break the paint is in the middle or down the center crosswise of the panel to trick your eye. if you just tape off at the fenders edge and have a door edge that is a different color than the fenders edge it is gonna tell off on ya. Jim

[Ronw435]

Thanks Jim I will try that. Just to be sure do you make sure you sand thru the clear just in that spot area?