Paint problem

[Russell Reay]

I am not an accomplished/ skilled painter, and yesterday's efforts make that pretty clear. I applied two coats of Evercoat Superbuild 4:1 using 55 psi of air in a 30-yr old spray gun. They 'cured' overnight in a 64* garage. Some paint was applied DTM, some over a prior coat of acrylic 4:1 DTM. Instructions were for 2-3 medium wet coats w/ 5-10 minutes of flash time, ready to sand in 2 hrs. I watched a couple of videos by Evercoat, and thought I followed their recommendationsWhen I sand it, the sandpaper loads up seriously as if the paint is not dry. It is worse with a jitterbug or palm sander, but happens even when hand sanding--using 180 grit. In some places I can even scrape the paint off with my fingernail (but not easily). I am pleased with the build, but need to know if I can proceed with just smoothing with a Scotchbrite pad, applying another coat of dark primer, then finishing with my chicle drab.

[old ugly]

sometimes if a two part urethane primer is sprayed over and acrylic lacquer base paint or primer it will stay gummy.
i don't know if that is you issue im just throwing it out there. i don't know the evercote brand.

normally a 2 part primer will sand nice after a day.

[J Franklin]

What was your shop temperature?

[Synchro909]

What sandpaper are you using? You should be using wet and dry paper and to stop it building up that deposit, use some soap with it. I have a cake of soap at hand all of the time and as I apply more water, I "sand" the soap as well.

[Dennis Pereira]

Did you use the right catalyst?

[Kurt in NJ]

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64 may be too cold, the cure may be very slow, or never
Perhaps it went colder in the night
I have used epoxy primer in colder temperatures, just for spraying, then moved to 70+ temperatures without problems.

[jb-ob]

Russel,

You need one of those cheap temperature guns to check the body metal temp, not room.

Where do you store your paint & catalyst, hopefully not in the garage.

Lastly, how old is the catalyst ? Paint & bondo last along time, catalyst does not.

What ever happened, you now have an unstable foundation. Best remove & start over. Sorry, jb

[Russell Reay]

Did not use wet/dry sandpaper--just regular woodworking stuff. Paint and catalyst is only a week old. Shop temp was ~65* when sprayed. Keep the paint in the shop where temp varies from ~28-~45 unless heater is turned on. Not difficult to move paint into the house if necessary. Instructions give performance details at 72*, but was hoping a few degrees less would not be a problem.

[J Franklin]

Turn up the heat, it might just allow a cure.

[bruceincam]

Vermont. It's probably pretty cold to be painting. You'll probably have to leave the heat on 24/7 to be happy with the results. 64 deg ought to be OK. Paint/primer will cure at lower temps but it can take a long time. I would just sit back and wait. See what happens in a day or two before you do anything. It never pays to be in hurry when painting.

You'll want to wet sand with wet/dry paper. I mix a squirt of Dawn in a 2 gallon bucket and use that as my sanding liquid. Either soak the paper in the bucket or fill a spray bottle and spray the liquid on as you sand. Wipe down frequently with a microfiber towel while you sand. Keep the surface clean. What paint are you using --- lacquer, enamel, urethane?? Two part??

[bobbader]

Sadly, your paint failed to cure in the time allotted and you probably used the wrong sandpaper. Using wet/dry paper with soapy water now might make the sanding problem go away but, it might also mask the fact that the paint is still not properly cured. JB-OB is correct. Your best bet, if you don't want more problems down the road, is to start over. Strip off what you've already done and wait for better overall temperature conditions. Take into account temperatures leading up to the time you spray, temperatures at the time you spray, and temperatures for at least several hours after the curing time suggested on the can or tech sheets. Even then, continue to do other things for awhile before taking sandpaper to it. Paint manufacturers' recommendations for anything short of over the counter spray paints like Krylon or Rustoleum are meant for professional climate controlled shops or, at the very least those with heat lamps or other means of controlled drying.

As somebody else mentioned ....... patience is your friend in this case.

[J Franklin]

I have kept mixed catalized paint in the refrigerator for a few weeks and it was still sprayable and cured properly, and hasn't posed any problems (for me). You can strip it all off or see if it finally hardens.

[Russell Reay]

Appreciate all the feedback. Sounds like I need to just wait until warm weather.

[Kevin in NJ]

First off as pointed out temps are important. You need 24 hours of well over 60 for a proper cure for poly resin.

Sanding, what sanding do you do? They are clear the repair area needs to be 80 grit with 180 to feather. That is where you need real good adhesion to the metal it best be 80 grit scratch. If you did not do that type of sanding then you had best take it all off and start over.

Not sure what you are trying to accomplish. The best order of paint for best adhesion is epoxy primer with the next coat of primer within the recoat window of the epoxy. I like the SPI products.

Of course I do not know how much build you really need. You can do pretty good with their high build urethane primer as you can thin it out to make it a lower build rate.

That being said, there is not anything wrong with how you are proceeding. Just the biggest error I see in many jobs is failing to follow manufacturers recommendations for sanding. This can cause poor adhesion to the previous layer. You also need to understand if the paint has a recoat window for the next layer. If you go outside the recoat window you need to sand properly.

Using an old high pressure gun is not saving you much money. You are likely better off with a low cost HVLP gun if you have the air to run it. The older guns waste a lot of material and with the cost of paints you can quickly recoup the cost of a gun. There is likely some merrit to looking for a used high quality gun and just resell it when you are done.

A final note. If you are using urethane paints you must have lots of air flow and keep fully covered even when mixing. The isocyanates used as hardeners can cause a allergic reaction. Hours later you might feel some chest pressure the first time. It will get worse with each exposure after that. The industrial asthma is what will kill you. This is based on a discussion I had with a university researcher.

[Tinbasher]

Hi Russ:

Let it sit for a week to cure out. It's because of the cool temp. If it's still gummy after a week, watersand the primer. John

[Russell Reay]

Good news! I cranked the heat up to 71* following yesterday's discussions, and this morning I have cure. The paint is dry and hard, and does not load up the sandpaper. That said, it has become clear that warm weather is my friend where paint is concerned. I will return all the sheet metal parts to out-of-the-way storage and maybe start on my huckster woodwork

[gdmn852]

Glad to hear the your paint problem is solved, not that much fun doing it over again, we had a heat oven in the body shop I worked in years ago and had to use it in cold weather, the acrylic enamel we used then would take awhile to set up well. Sounds like the problem you have.

[burner31]

Originally Posted by Russell Reay

Good news! I cranked the heat up to 71* following yesterday's discussions, and this morning I have cure. The paint is dry and hard, and does not load up the sandpaper. That said, it has become clear that warm weather is my friend where paint is concerned. I will return all the sheet metal parts to out-of-the-way storage and maybe start on my huckster woodwork

Wait...you have heat in your garage?
I've heard of such things...but thought it to be just a myth, you know...like air conditioning in a garage.
I've tried to get my heater to come in the garage with me in the winter...but she says it's to cold.
(That's the motor for the '57 Chevy...not the A)

[Oldbluoval]

Just a side bar….
Be sure a read and follow mfg data sheets. I think you did
Also make sure of the aging of product especially the hardeners..
watch for water in air lines going into paint.

[Russell Reay]

Originally Posted by burner31

Wait...you have heat in your garage?
I've heard of such things...but thought it to be just a myth, you know...like air conditioning in a garage.

There is an old wood stove in one corner of the shop, but it won't hold a fire overnight. I also just installed a 7500 watt heater to the garage ceiling. It helps create a comfortable working temp (55+), but would cost a fortune in electricity if I tried to maintain painting temp for several days.