I recently decided to try to repaint my 85 ford truck by myself, there was no rust or peeling paint it was lust a ugly color. So i sanded the whole truck with 80 grit, fixed the small dents it had and went out and got a gallon and a half of omni 2k primer and shot two coats on the truck out of my hf paint gun. then i let it sit for a day and dry and the primer was kind of rough so i wet sanded the whole truck with 800 grit paper feeling for rough spots then let it dry. So now the primer seems alittle shiny in places like maybe i sanded it alittle to much? or maybe a to fine of paper?so my question is how do you no if you sanded the primer enough or to much? and does what i done sound like its alright so far,so now im going on vacation for a few days and am wondering if it will be ok to wait and paint ss paint when i get back, truck is stored in garage. thanks guys for the help

 

so i was doing some reading online and now im worried that 800 was to fine, and maybe i should go back over it with 500-600, if i dont will the color coat stick ok? when u look at the primer it kinda looks glossy/polished, im thinking i sanded it to much. Btw this is not a show truck at all just looking for decent paint job. Once again thanks

 

I think 500-600 is too fine.
I think no more than 400 grit for primer.
You really don't want to go higher than 400 unless you are sanding between coats or color wet sanding.
That is what I have read in the past and it worked very well for me on my last project.

 

So do you think i should go over it again and wet sand it with 400 and it wont show scratches through the color coat which will we be ss metallic

 

Mmm, one definitely goes with 400 grit to prep a surface for a solid color. I know on metallic base you do not want to use 400 as it is too coarse and the metallic particles will set up along the walls of the 400 scratches. One does 500 or better 600 when doing metallic base. You say that you are using SS metallic paint so I don't think I would go below 500 myself.

 

Ok so should i resand then? Do you think il have a prob with paint sticking

 

Not an expert. That said, 80 grit was too coarse to leave in the beginning. I take it down to 320 grit then shoot the primer, last coat reduced to a sealer. I have no experience with metallics. Wait till you can prime and shoot color within specified times and you gain the advantage of the chemical bond between the two, not just a physical bond. The roughness you mentioned probably came from shooting too dry, not enough pressure etc.
We do have some pro's on here, hopefully one will join in.

 

Are you going to be spraying a light color or dark? The Omni primer is pretty good stuff but it does shrink so be prepared to see some 80 grit scratches under the paint job. If your going with a light color you'll probably never see it. Dark colors show more.

As for the primer, 800 grit is pretty fine. I usually sand primer with 400 for solids and 600 for metallics and pearls. If it seems shiny in alot of spots just buy a few gray scotch brite pads and rub it down. This will give you a a good tooth to grab and isn't overly aggressive.

IF your really worried about the sand scratches from the 80 grit, sand the whole truck down with 180-220 sandpaper and prime it again. This should take care of the problem.
If you have some more questions feel free to put them up. I try to check the paint section regularly.

 

ok sorry guys been awhile since i posted my original question, i ended up painting it with kirker acrlic enamel paint, mack green is the color i got alot of orange peel in the paint and i put 4 good coats on with hardner, im wondering now if im ok to wet sand and buff after a few days of dry time. thanks guys for your help.

 

To check push your finger into the paint. If a print impression is left then the paint is still soft. With 4 coats on it the paint could still take awhile to dry although with urethanes you are told to color sand starting after 24 hours. You used enamel and I believe it stays softer than urethane.

What do you have for tools? Grits? Buffer? Compounding polish? I just finished painting my 73 Dodge on Monday and I am now color sanding the car. Some runs but only a little OP so I am using 1000 to start. On a hard block I can hear the sandpaper and fell it through my fingers tips as it runs over some OP. When the peel is knocked down the sound and sensation go away. Happens quickly and then onto 1500 and 2000. After that I use 3000 trizact on a Makita rotary. I also have 1500 clear coat discs but preferred to use my hand instead for the control. The reason for all the grits is that the next finer grit refines the scratch of the previous grit. The finer the scratch the easier and quicker the buffing out. Getting out 3000 scratch is very easy as the surface already has a low shine to it.

The goal is not to eliminate the OP but to make it representative of what it would have been like in 1973. If you have seen the paint jobs on new cars you would know they leave the factory with varying degrees of OP. So don't worry about leaving some as that is better than cutting through paint near an edge.. Better yet put tape at an edge so you don't run over one in your formative stages.

Once done then I use Wizard's Mystic Cut with a special combo wool pad on the Makita 9227. Tight areas I use a 3" orange foam pad so I don't burn edges. Then finish up with Sure Finish on a Makita BO6040 using forced rotation to eliminate swirls. Great machine but at $300 you better have lots of cars to paint like me.

 

Thanks i appritate the help i painted tues day so maybe il wait one more day its been in the 80s and its in a garage

 

ok, starting from the top.

sanding the entire thing down with 80 and priming over the 80 grit scratches is a headache waiting to happen. Anything you are going to prime, needs to be finished off with 180 AT THE VERY LEAST. you will be having to apply way to much primer to get the build necessary to fill the 80 grit scratches. Primer is to be used as a barrier coat to lock down the bodywork and substrates. Not as a filler.

The roughness you describe depends on two things. It could be the gun was set up correctly and you are simply talking about the texture of the primer, which should just be a light orangepeel texture, or if it is a roughness like you havent shaved in a week, then its incorrect gun setup. To me it sounds like too much air pressure, and not enough fluid. Back your fluid cotrol out a couple turns. typical priming is done around 25psi for a conventional gun and around 15 for an HVLP at the cap.

The shinyness of the primer.....nothing to be concerned with. look at it like this, You wetsanded the entire thing down with 800 grit. 800 isnt meant to be used for sanding primer. Typically meant for imperfections while painting. Sand the primer with 5-600. That fine grit of 800 will produce a gloss. Even if you go and sand down a Clear coated finish with 800 or 1000,it can be completely sanded, but you can still see a reflection at an angle coming off the surface because of the fine grit of the paper. Now, If you arent going to seal the primer prior to painting, then go back over the primer with 600 or 800 throughly to get rid of any scratches. But if you break through in any area, it will need to be reprimed before painting. Dont try to paint over exposed body filler. It'll act as a sponge and look like a big bulls eye on the truck.

As far as the Acrylic Enamel paint you are using, Typically, the colder it gets, the longer Enamel takes to dry. all dry times if you look on any can of whatever product you use, are based off of 70 degree temperatures.

Urethanes are softer than Enamels. Not the other way around. Enamels are used more for an industrial coating. they dry harder, becoming for chip resistant and chemical resistant.

While you are spraying the enamel, a good practice to do is to go and take your time first and foremost. DO NOT try to wet it and make it look like a mirror on your first coat. It will have some orangepeel and that is perfectly fine. You are going to let that first coat set just a little longer than the next coats because you are going to let it be the "tack" coat. Your 2-3 coats(which are normal, I see no reason to be doing 4 coats. You are going to be waiting a while for all the solvent to come out of it to dry completely if you do), need to be applied in a simple medium wet coat. You can push it more on these coats to get it to flow out, But it will only go so much so be sure you are using the proper mixing ratio AND the proper temperature reducer. Too heavy on the trigger with too fast a reducer, Orangepeel hell. Too heavy on the trigger with too slow a reducer, Its oging to run to the floor. In between your coats, normal tack time is 10-15 minutes with an Enamel if I remember correctly. Do not quote me on this because every application is different with different temperatures, setttings, and humidity. But between each coat, wait before putting the next one on, until you can drag your finger lightly across the tape closest to where you are painting, and it doesnt leave a mark in the paint on the tape. When it does that, continue with the next coat.

Sanding can be done like the guy above me said. A block and some 1000 grit does wonders for getting out runs. But if your impatient, you can go through. I personally use a razor to get out any clearcoat runs I get, but thats a different technique all together. sand with 1500 and step up on your sanding prior to buffing. dont jump from 1500-3000 in one step. If you go through the order of 1500,2000,2500, 3000, you wont have to work the buffer at all hardly to get rid of the sand scratches.

Name of the game is to take your time and have patience. Let me kow if I can be of anymore help

 

To be exact the paint desired for industrial use, marine use and aircraft use is polyurethane enamel and not enamel. The chemistry that goes in with the paint, besides the pigment, is what either keeps a paint an enamel or makes an enamel into urethane enamel or polyurethane enamel. I use a polyurethane enamel for a ship because it is UV, acid, alkali, abrasion, chip, salt and water immersion resistant. Enamel wouldn't last a year. Of course, when painting warbirds, I have also used polyurethane enamels since aircraft need softer paint that will flex.

As for cars then standard enamel can be as hard as porcelain since they had to withstand the environment back in the 50's and 60's with what was available. As we also know the harder the paint the harder it can be to correct. Today I'm not sure the enamels are as hard as they were in the 50's since I'm sure there have been chemistry changes due to EPA regs.

So I would have been more accurate to say urethane enamel has infinitely better durability than enamel due to the isocyanate activator which also allows it to dry faster by not relying on air temps. This then allows it to be color sanded sooner than enamel.

 

Didnt know we were talking about urethane enamel. I misread the OP then. But you are right on the money with that point. I typically use Acrylic Enamels because of the dry times(but again, depends on conditions). Once it locks up and sets, you cant hardly sand it.

 

Thanks for the help guys i wet sanded and buffed the fender and.door yesterday and it looks very good thanks again for all your help