Primarily Petroliana Shop Talk Forums Shop Talk Petroliana Forums General Petroliana Discussion Paint temp question

So I sprayed my 36B in my friend's paint booth a few weeks ago. Let the paint set up overnight and loaded it in my truck the next morning with shipping blankets. I guess he turns his heat way down at night and it didn't fully kick and a few of the panels got some marks on them that wouldn't buff out. So I had to scuff the whole panel and will need to repaint.

My question is, it's really hard for me to use his booth logistically and it's a woodshop so there's always a big risk of sawdust settling on my stuff while driving. I'm using PPG Omni single stage with fast reducer. Could I spray this in my unheated garage (usual winter temps around here are in the 30s) and then move to my heated basement to dry? I could possibly warm up the garage some with kero heaters but would obviously need to shut off before shooting unless I want to blow myself up.

I think sometimes going single stage can be a draw back. In your case the scuffing of the blankets if it had been on the clear, you could have wet sanded the area in series with 800, then 1000 and 1500, 2000 and so on. Then buff with a machine polish. In other words I think having several levels of clear makes things more forgiving and quick fixing in cases like yours. Ive taken items out in 40 degree afternoons only having the parts, paint supplys and gun inside where its warm and with compressor ready, I quickly sprayed outside and brought the items into a warm garage.Paint products dont like or manage well in these ambient temp conditions, neither do I!

Chris, when Lee paints with single phase when it's cold outside, he sets the panels near a kerosene heater to warm them and then takes them outside for a quick spray. After finishing, he doesn't touch them for a couple days or more. Brady

Air dry time for Omni MTK is listed at 16 Hrs @ 70 degrees. When the the temp goes lower the dry time goes up.

You can spray your parts in the garage. Check for ignition sources such as hot water heaters ect. That could cause a fire before spraying. Just make sure to have some ventillation. Have a proper paint respirator. Use at least a box fan in a door way. I would reccomend putting some filter on the fan so that you do not cloud your neighbors car, or your driveway with overspray. That can be a big problem if you live near other people. Also make sure that the metal temp of the panel is at very least around 65 degrees. And moving wet panels to a basement without maring the finish will also be a trick. Be careful.

I've painted in the garage (it's actually more of a workshop) plenty of times, just never in the winter. Thanks for the input.

I've done a couple pumps with single stage Omni, painted in my garage. If you get any gunk in the paint, I've never had any issues wet sanding with 1000/1500/2000 and buffing it out. Just cause it's not cleared doesn't mean you can't wet sand it. Are you sure you have to repaint? Have you tried sanding with high grit?

Did you try to wet sand the area and go thru to primer?If not you should have enough material to get the scuffs to block out.I've even brush touched single stage that I've burned thru buffing.Build up the bad area and let it dry completly and wet sand and buff it out it will turn out great.I've sprayed in cold temps but you need the metal warm to start with.Get the garage up to temp and kill the heat source spray it out,let it kick a little and carry them inside to cure.
Joe

Two things you have to always keep in mind are the ambient air temperature and the metal temperature. A panel that sat in a 32 degree room for hours will not warm up as fast as the air if heat is turned on.

Paints that require the use of hardeners will not properly cross link and therefore not cure below 55 degrees. We tell people they need to maintain preferably at least 60 degrees for eight hours after spraying. Yes, paint will eventually dry(with the addition of heat and time) even below 55 degrees, but you do not get the chemical resistance and durability.

Some people warm panels up before they spray them, but you have to be careful not to get them too hot. If the panels were 85 degrees and you use a fast hardener and fast reducer, paint will kick too fast and probably won't flow out.

As stated earlier, 16 hours dry time at 70 degrees. All paint dry times are based on 70 degrees and 50% relative humidity. You must adjust hardeners and reducers for temps above 70 degrees and allow extra time for temperatures below 70.

Dry times are going to be the same for single stage or clearcoat.
One other option to consider are accelerators. There are two kinds. True accelerators such as PPG DXR81 begin to kick as soon as you put it in the paint.Pot life of paint is shortened. It will completely through cure the paint in less time. The other is an enhancer such as PPG DX84. It will get it out of dust faster but not through cure faster. Also doesn't kick until paint is sprayed.In the Omni line I'm pretty sure MX195 is equivalent to DXR81 and MX200 to DX84. I'll have to check to be sure. Excess use of these products can diminish the flow and finish of paint and clear. Read P-sheets.

For years I have seen people spray paint(during cold weather) while its warm and then turn the heat way down overnight(usually in poorly insulated buildings). Then they call complaining that the paint wouldn't dry and that there must have been something wrong with the hardener. Remember, air and metal has to stay at a minimum of 55 degrees(preferably 60 degrees) for hours after spraying paint.

Also not mentioned is that you need to have air exhausted out for a good period of time after spraying. As solvent evaporates out of paint, it needs to be exhausted out or it will settle
back on panels. If panels are laid flat you are more likely to get die back from solvent settling back on panels.

Sounds like the paint was too soft(not cured) and the blankets made too deep of impressions. As has been stated earlier, you should generally be able to wet sand and buff as long as there is enough material there whether it's single stage or base/clear.
Pat.

Yeah, the paint must not have cured enough and it made some bad indentations. I let the paint cure for a week in a warm space in my house and wet sanded with 1000 then 2000 grit but couldn't get to buff out to my liking. I have extra paint, so I figured I'd reshoot it and do it right. I also had a run on one of the doors that I didn't see that I sanded down. I've hit the paint with 220 for a new coat, so no going back now!