When you spray todays urethanes , and urethane enamels , there is a waiting period in between coats that we call " flash time" for the guys in the industry . The reason for the "flash time" in between coats is for the solvents used to thin the paints , primers , sealers , etc, down must have enough time to "flash" out of the chemical being sprayed and carried away by hopefully a fan system of some sort even if you do not have a booth . If you DO NOT give your chemicals this required amount of time for the solvents to get out and lay another coat of paint or whatever on top , you have now trapped the solvents under that new coat and it has no way of getting out now other than busting through the new topcoat making tiny pinholes that we in the industry describe as "solvent pop" and looks like hell and no amount of buffing will actually cure the problem . It may look better , but it isn't actually fixed correctly . Here is another common mistake that people do when they have the car freshly painted . The first thing they want to do is protect that new finish so they think waxing it will surely be the way to achieve this protection . WRONG...WRONG...WRONG !!!! The Urethanes of today take around a 90 day period before they are fully cured with all the solvents finally being considered out and away . If you wax a fresh paint job BEFORE this curing period , the wax will seal the pores in the paint that is letting the solvents escape . Now they have no way to get out once again other than through the top . This is a common reason you see "blisters" in fairly new paint jobs that the new owner has already waxed right when he or she got it out of the paint shop . Now they are pissed and cussing the paint shop . Same thing in the old lacquer days when guys would wet-sand and blow the car off and start shooting the lacquer over what they THOUGHT was a dry surface just because they THOUGHT it felt dry to the human touch . Tip : DO NOT WAX A FRESH FINISH and if you do decide to cover the car with a new car cover , USE A QUALITY BREATHABLE CAR COVER that the solvents can escape from . I suggest to my customers to just leave them un-covered for awhile and let the paint "do it's thing" ( CURE FULLY ) before they start playing with waxes and show car glazes . Just keep them clean and towel dry with a soft towel and NEVER let your buddies walk up to a fresh paint job with dust on it and start touching or rubbing it because he is now "SANDING" the cars finish again . Like it or not , I call fresh paint sitting in my shop " IDIOT MAGNETS" , and you guys that own paint shops know exactly what I mean ! Bare metal , finished out bodyfiller , and paint will attract them like flies in **** every time ! LOL Hope my lil tips help you if nothing else , Jerry
Jerry, excellent information!. If anything, if you don't the the flash time take place, you will also get runs. I see people who are too impatient, just start spraying it on thick.... I have also seen people wax those new paint jobs , I always wait 3 months. Another tip with paint: I have always heard it is better to do the color sanding, or wet sanding within ther first week, while the paint is still "soft"....once it gets "hard" it is more difficult ot sand and takes longer. Again, we are tlaiing about super fine wet sandpaper and water.....no chemicals.
i'm not painter, i have never painted a car, i have seen blisters and poping and wondered what that was all about, thanks for the info.
Alot of times the blisters are from painting too early after wet sanding and painting over moisture . That moisture finally dries up after some time and you now have an air pocket " blister" that is usually more noticeable when the car's paint gets warm because they expand from the heat and then go back down when the paint cools off . If you are in search of buying a car that is "restored" , always try to look at the car inside a shop with florescent lighting that will show flaws in the finish much more detailed then sitting outside !
Great post Jerry! Is your 90 day wait for during warm weather? I'm leaving off even buffing my new paint until it gets warn again up here. I've read that you should even allow time for thinner escape after color sanding before clear coating. Flatman
90 days should be long enough if it's not really cold and really wet where the car stays during the curing process . Too cold of an environment on fresh paint is not good either on any new finish . I'm not sure I understand your second question though about "color sanding" ? We normall already have the car cleared when we consider "color sanding" which is fine sanding the nibs and imperfections out of a finished paint job and buffing afterwards for a show quality finish . If you are talking about waiting to clear over a freshly sanded paint , just as long as you have all the moisture from the wet-sanding out , you will be fine . That clear will breath also . The problem with "solvent pop" is they layer of paint that is still releasing the solvents out of the paint now has another layer over the top that is "skimming" ( starting to set up ) and the solvent is still trying to escape from the coat under it . Hope this cleared or answered your question ? Jerry
How long should one wait in a 65-70 degree booth between coats to allow the solvents to evaporate?? Acrylic enamel paint. Thanks for the tips guys.
Thanks for the tips. In the old days sunshine was the best curative. Let the solvents get out. In nasty weather, find a bake oven. A modern heat controlled spray booth is the modern tool, but not everyone has access to one.
65 to 70 degrees is a tad cool BUT I LOVE IT around 75to 80 myself because you can flow the paint ( not bases !) like gl*** in that range ! In the range you are talking about , depending on your reducer which they offer in different temperature ranges , I would go about 30 minutes in between coats which doubles the normal "flash time" of 15 minutes on most of todays finishes . Just double it in cooler temps and you should be okay .I have stated it before but I will do it again , "USE A CLOCK !" because 5 minutes standing there in a booth with a spray gun in your hand seems like 15 !I walk out and go in my office , prop my feet up on my desk and look at clock like a Hawk ! I personally have two large heaters that blow directly in front of my filters ( I have a "cross draft booth" ) and with a 30 degree temp outside , I'm in my booth spraying away . I use the large Propane heaters as opposed to Kerosene . NEVER let your temperature fall under 52 degrees while spraying or while the car is trying to dry . Even catalyzed coatings start to stagnate ( quit drying ) in the mid 50's or below .
I'm poor but my booth is 20'x30' and I keep the intake filters new and the 2 heaters work well for me . A high dollar booth doesn't make the paint job because I've seen some pretty ugly **** come out of a $100,000 booth right across town from me just from ****ty prep work and this guy runs his mouth about me constantly but it's funny that I have painted 3 of his relatives cars in 4 years ? Let your work speak for itself because the day I have to stand in my parkinglot and run another man's shop down to get a job , I'll close my doors ! There are good shops everywhere and I give credit where credit is due . Even if I looked at a man or woman's car and thought it looked like a ****py job , you would never hear it out of my lips because that is THIER CAR and they are PROUD of it ! Now if they are bringing it to me for a professional opinion , I'll be honest with what I see in front of me , and that's the difference .
Hope I didn't offend anyone with these post trying to sound like I'm some kind of know-it-all or something . I am just trying to help althoughs others think I'm rude and just a **** starter . I am truely sorry if I offend anyone with my tips on painting because that is not my intention at all , Jerry
Good, solid tech advice should never offend anyone, especially when it come from a professional. Lots of hobbyists here who want to know the straight facts. Flatman
Not at all Jerry. Painting is one area I really have alot to learn about. I took your response as good advice. I appreciate it. Thanks!!
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