180, do i sand it again with 320, then prime it? Or primer then sand with 320/400?

IM going to attemp to paint it in the next few weeks. And i could use a little help. Its gonna be black so i need to get it as perfect as possible. I have one book and have read alot but still a little unsure about it. I painted one car before came out ok. But its been years.

I have a decent compressor and a decent gun.

Heres how it looks now, IM a little unsure about what to do with the high spots where the gel coat is gone. Is it ok to primer over that then galze it where i need to?

Thanks for any help!

 

Ok,
You got the whole thing blocked with 180?
Wax and grease remover, tack, prime...(two part catalyzed primer.)
I would then block with 220...especially with black. Guide coat between each blocking. Then if you still have low spots, re-prime and block again with 220.
Then final prime with a bit of reducer in your primer, lay it out like you would paint. (remember, at this point you're just going after scratches.) Block with 320. Always with a nice criss/cross pattern. should be X's over the entire surface. Follow the contours.
Depending if you have breakthroughs... I would just guidecoat the last block and wetsand (I use 600g on black, but 400 or 500 is fine.) all of the guidecoat out. Use a soft block or spongepad, or you'll have fingermarks showing.

 

Hi Kevin thank you...Ive read your posts on paint and body work.

I did block sand the whole hood with 180. I used some rattle can to give it some color when i first bought it. I will use the good stuff next time.

When i block sand with the 220 again do i sand it all back off again? Or just enough so the low spots are visible? I sanded it till all the lows where gone. Why do it again? To be sure its flat?

Would a quart of primer be enough to do the hood?

 

No, do not sand it all off. Mix up enough to do 2-3 good wet coats of primer. That will build well for the first block. Get a good longboard, either a Hutchins, or something comparable. Block in X patterns with the slope of the hood. On the first pass, do the entire hood, in sections. When you hit breakthrough, (when you actually break through your primer to the gelcoat...) You're done. Do not keep blocking. This is the point where you want to re-prime. If you still have low spots that the block didn't touch, just rough those up before you re-prime. Your giuidecoat is what will show all your lows. Usually a spraybomb of a different color. Where that color is left and not touched by the longboard, you know where you need extra fill.
Make sure you sand all edges and non sanded areas before you re-prime.

 

Oh ok...i see.. i think i understand now.. im trying to build up the surface. till its flat with the primer, each time i block and prime it. I build it up and make it a little straighter/flat.

Thanks again you have been a big help! I will up date this post as i go.

Mike

 

Quote:
Where that color is left and not touched by the longboard, you know where you need extra fill.


Would i use a glaze with a catalist here? Or primer? The hood doesnt have any really bad spots now took care of that the first pass. I guess im asking if its ok to use it here over the primer after i rough the low spot up if needed?

 

Depends on how low the low is... There is only so much that primer will fill.
Usually if the board just is skimming the surface of the low, like sanding it somewhat but not taking all your guidecoat off... your next priime will take it out.
If you literally have a low spot that is no where near the height of the rest of the panel... Just scratch it up with 120 or 150 and fill it with icing.

 

with the guide coat you basically wanna mist the hood with a color. then when you sand, its super obvious to see where the sander has not hit yet. keep using 320 until you can have all primer with no guide coat or gelcoat. then prime one last time, and wetsand with 600, and like he said, spongeblock or something like that. once all guidecoat is gone from wetsanding, grease remove and tach, and youre ready to hit it with the color.

 

ok thanks Kevin...i will post back when i get further along!

Hi Adam...

I went by the local painter supply today and picked up what the sales guy recomended.

I bought a quart of Epoxy primer, quart of primer surfacer, and a quart of color. He said not to sand the epoxy after i spray. That i just need to primer over the epoxy with in a certain time frame. or i would have to scuff and re shoot it. I have all the papers on the products to go by as well.

Its all PPG stuff the paint is a single stage omni urethane. I hope this will look good even though its not base coat clear coat. He said i can color sand it and buff after i spray it. Ive seen some decent jobs in single stage. I just thought it might be easier for a first timer. Dont know why.

I also picked up a couple HVLP guns. 1 for(1.7mm)primer, one for the(1.4mm) color, and a jamb/detail(1.0mm)gun. They where budget priced so again im hoping they will do a good job.

 

If all goes well i will shoot the epoxy this afternoon.

For surface prep...on the expoxy primer. under sanding it says 120-180 for bare metal. And 220-320 grit on old finishes,body filler.

i have a question...is it ok to shoot the expoxy primer over the 180 that i sanded with? Or do i need to sand it with 220-320 first?

Mike

 

It wouldn't hurt to give it a quick wipe with the finer grit, it'll give your epoxy the proper adhesion. When it comes time for your base coat, try not to hit the filler primer with anything over 400 grit, again, for adhesion properties.

go here for some useful info : http://www.autobody101.com/forums/

 

Hey thanks for that link i didnt know about that forum.

 

Well i just put the two coats of epoxy primer on. And i did resand it with a long board and 220 grit.

This gave me a chance to play with the gun a little. I put a couple pieces of paper on the wall to test the spray pattern. I played with the settings and air pressure. Got the best pattern and started shooting.

Im not sure what pressure to set the gun and compressor at. I have a gauge on both. Could someone tell me how to set it up. I used 20psi at the gun first then around 60psi. It seemed to come out a little more grainy in texture with the higher pressure.

What should they be set at? It a HVLP gun.

Mike

 

Mike,
I really wished I would've been able to get to you before you sprayed the epoxy.(I read your post at work this morning.)
Epoxy isn't necessary on a fiberglass part.(It won't hurt...but it is not necessary.) All it really does is prep the steel, and protect for longer holdout. It will also help adhesion, and that's why ultimately, it couldnt hurt. (you could accomplish the same result with complete sanding.)
Basically the store sold you something you didn't need. (money you could've spent to upgrade your paint.) One stage is fine for black, and the nice thing is you can always wetsand it down and clear it if you need to. (Or want to.)
Use plenty of medium coats. dont try to cover everything at once. Make sure they sold you the correct reducer for the temp you will be spraying. (not a huge concern for one panel, but will be easier in the long run for flow and minimize reaction and solvent pop. Pay attention to dry/flash times. Especially with a single stage.
Somewhere around 40lbs at the regulator should get you good cap pressure. (most HVLP's like somewhere around 20lbs at the cap, which is hard to determine without a special gauge.) But start at 35-40lbs and work your way up or down from there. Set the pressure non triggered, then trigger it 1/2 way, (which is all air, when you trigger it all the way, that's when you adjust the ammount of fluid.) and watch the needle. The gun's transfer efficiency comes into play at it's optimum pressure.

 

Hi Kevin...thanks again i really appreciate your help.

Oh well...I thought he said i didnt need to sand the epoxy before i coat it with the primer surfacer. Does that sound right?

Would that be 40lbs at the gun gauge or at the regulator at the compressor?

 

40 at the gun.
And no, you do not need to sand epoxy, for a limited ammount of time.
DP with 401 activator used to say you have up to a week to re coat.

 

I was just gonna post that 40 at the gun was working great. Did some test patterns on the wall.

The sheet says coat with in 72 hours or the epoxy primer has to be scuffed and resprayed.

So i will be spraying the primer surfacer tomorrow night. Working with the primers first. is giving me a chance to get some practice time with the new gun.

I got a chance to see the hood wet with the primer and its looks pretty straight so far.

 

I put 3 coats of primer on and blocked with 220.

 

Well...after block sanding this thing 5 times i think i have it straight. That includes sanding off the rattle can stuff. It took that many times to keep from sanding thru to the epoxy primer. Fiberglass is very wavy.

I hope to put the color on tonight or monday. I could use some tips on painting the color. should i spray all the edges first, or just as i go around the hood? That way IM not blowing overspray on the top. Or does it matter?

The paint is a 4/1/1 ratio, i have a quart of color and a half pint of hardner. The sales guy said i should use all the hardner for the quart. So how much reducer should i use if its the same as the hardner it would be a half pint right? Should i add more reducer?

I could use any spaying tips took alot of work to get it this far and im really nervous about spraying the color. I found some good help on setting the gun up. And i wont start spraying the hood till i get a good setup on an old fender i have. I guess i can allways wetsand/and buff if it comes out bad.

 

sounds like your using acrylic enamel, do you have a measuring cup for paint? It shows you the exact way to measure it...down to the last drop

 

Shawn's right, You need a mixing cup to do this right.
I'm surprised the paint store didn't offer you one, especially if you bought all your supplies there.
I would paint the back side, if you haven't already... prep it with a scotchbrite, seal and shoot. (hopefully they gave you enough to do both.)
Wait a couple days, and paint the outside. Reverse mask along the bottom side edge, and drape paper off the tape, hanging down.

Hey Shawn,
Long time no see. How's everything at the dealership? Hope things are well. Get that black beauty out from storage?

 

Hey kevin..I got the mixing part figured out, i was doing it right. Just a little unsure at the time. I do have some of those 1 quart mixing pails. Sticks and strainers were free but i had to buy the pails. I found the mixing ratios 4:1:1 on the side.

Hi Shawn..The paint is a PPG/omni MTK Acrylic Urethane. Supposed to be decent paint.

I wetsanded the hood with 600 last night. It looks pretty straight with the water on it. I did have some small areas after wetsanding that went thru to the epoxy primer. Is it ok to shoot the color over them? Or do i have to reprime those areas?

Can i use the epoxy on the underside to seal it? The shoot the color?

Thanks!

 

Well here she is....Other then a few runs that will have to wetsand out. It turned out better then i thought!

 

Kevin...thank you for taking the time to reply to my dumb questions! You where a big help to me!

Mike

 

Anytime bro...
Looks like you answeed all your own Q's.
Nice work, you did it all yourself, gained some knowledge, and some appreciation, and saved yourself about 5 bones.