painting questions

[mustbereel]

Hi All,

I have been hanging out here for awhile (even replied to a few threads where I had firsthand knowledge) but this is my first request for help. I have been all consumed with my restomod project for the last 9 months and I am finally getting close to paint time. The car is stripped and on a rotisserie. I have finished all of the major bodywork (very little of the original car remains) and the car is in primer. I have spent most of my spare time in the last few weeks working with primer, filler, surfacer, guide coat and sanding. Many, many hours of sanding. With any luck I will be ready for a couple coats of sealer this weekend followed by color! I am using an Epoxy primer/sealer followed by urethane bc/cc. This will be the first car I have painted.

With the background out of the way here are my questions. What grit sandpaper should I use before I shoot the sealer coats? Should I sand after the sealer and if so with what grit? The final color is silver-blue metallic. I have heard you should not color sand metallic so I plan to shoot 2-3 coats of color followed by 3 - 4 coats of clear to allow for sanding out orange peel and imperfections. Any suggestions on sanding between the layers of clear would also be helpful.

Thanks,
Brad

 

[zookeeper]

Brad, first off, congratulations on painting your car yourself! I know it's a huge undertaking, but trust me, the results are worth it if you take the time and get each stage right before you move on to the next. Having said that, you need to realize that any answer you get here is going to be, at best, a generalization of what you need to know. Have you already picked out a paint brand? If you have then they will have detailed information on what you need to use, and you need to follow their instructions like your life depends on it in order to get good results. All the information for any particular brand is readily available from the place you buy it, whether it's a local paint store or an online store. I used House of Kolor products on my car, and bought the majority of it from www.autobodydepot.com but I also bought some of the stuff at a local paint store. I got information from both sources as well as from House of Kolor's tech line. I don't want to seem like I'm passing the buck, but that's the best overall answer I can give you. But I will tell you what I did, first, I stripped my car to bare metal, then did what metal work was required. Then I shot the bare metal with a two part epoxy primer. As per HOK's instructions, I shot 2 coats of primer over any bodywork and three more coats over the whole car. I then blocked the car and re-primed it until I was sure I got it straight enough for paint, I did all my blocking with 220 grit, then 320 grit, then 400 grit. When I was ready for paint, I remasked the whole car and shot it with a white sealer. Two good coats was all that was needed to cover it, so I let it go at that. House of Kolor recommends the sealer sit no longer than 3 hours before top coats are applied, so I didn't have time to sand the whole car. I really don't feel it's necessary anyway, but I did go over the dry sealer in a couple spots with some 400 grit dry, just to get out a couple specs of debris. After that, I mixed the base, wiped the car down with a tack cloth and shot two coats of base. Since I was shooting white base over a white sealer, it didn't take much to cover it. The base dries fast, so as soon as I cleaned the gun after the second coat of white, I mixed up the clear and shot three wet coats of clear. After I cleaned the gun, I left the shop, leaving the fan on and didn't go back in for about 4 hours. After a couple days, I sanded the orange peel out of the clear with 500 grit wet, then remasked the car and shot three more wet coats of HOK's "Flo-Klear", which is a super wet-looking clear that is supposed to be easier to buff. I haven't buffed it yet, but I can tell you that it looks like glass with nearly no orange peel at all. I credit that to following the instructions and using high-quality materials. I'm no wizard when it comes to painting at all, but by keeping the shop as clean as I could and as warm as I could, as well as wearing a paint suit and paying attention to the details I ended up with a much nicer paint job than I could have hoped for and a heck of a lot nicer than I could afford to pay someone to do. You can too, trust me!
Jim

 

[zookeeper]

Here's a shot of my car right after I finished the stripes. As you can see, it ain't exactly Boyd Coddington's paint booth, but by keeping the floor clean and wet, and remasking the car everytime I sand anything, it has very little debris anywhere.
Jim

 

[mustbereel]

paint confusion

Hi Zookeeper,

Thanks for the reply. You car is looking great! Part of my problem is that I have been reading too much and have found conflicting info. I wanted to get an idea of what some of the other DIY crowd has done and what their results were.

I never intended to paint the car myself but the longer this project drags on the more I am determined to do everything myself so I can do it the way I want it. I hope I am not disapointed with the results.

Luckily we have been having a warm winter and should have temps in the 70s this weekend so it's a good time to paint. But boy is it a lot of work!

Brad

 

[69 Rustang]

Rather than telling you how I would do it--I suggest you get the technical data sheets for the product you are using as the paint manufacturer likely has recommended finishing grits. 500 grit may be good enough, but I would hate to find out it wasn't what you should use per the manufacturer and have a problem later. Whereever you bought the paint, they should have TDS's that they will give you or let you look at. Sounds like you have been really busy--care to come over and work some mud on my car?

 

[mustbereel]

painting is fun!

Hi Rustang,

Sounds like good advice. I have double checked the data sheets. Looks like 240grit before primer/sealer and 400/P800 before basecoat. More sanding. Great. If it wasn't for the quality of the cars I've seen here I might have been happy with an o.k. paint job. Now I want perfection and that's what really takes time. I don't know if I ever want to do this again. I like the modification/mechanical work but next time l'm leaving the bodywork/paint to the professionals.

Brad

 

[Silver66FsBk]

if this is your first time painting you do not want to start with a metalic base
you should just pay someone or take the car to a shop that can paint your
car.

but if you decide to give it a shot remember to allways keep stiring your
paint as your spraying.

 

[mustbereel]

contingency plan

Silver66FsBk,

My plan is to shoot the underside, engine compartment, trunk and interior first. Most of that will never show and it will allow me to practise. If I totally mess that up I will take it to someone to paint the exterior. I've got too much invested in this car to have subpar paint, but it is a driver not a show car. I've heard light metallics are the hardest to paint. Of course I didn't know how to weld when I started this project and I'm pretty good at that now.

Stir while shooting.
Thanks,
Brad

 

[zookeeper]

I like your attitude! A good way to get even coverage on metallics and pearls is to hold the gun a bit farther away (7 inches or so) overlap your passes by 50% and use light coats. Don't try to "wet" base coats with a basecoat/clearcoat system or you'll have blotches (blotches? We don't need no stinkin' blotches!) Sorry, I couldn't resist. Anyway, the rule of thumb for bc/cc paints is to just get even coverage with the color and just worry about making it shiny without runs with the clear. Modern metallics are much easier to shoot than older, single stage metallics ever hoped to be, you'll be fine.

 

[Cobain03]

im somewhat of a DIY person myself.

(ps, i like the color scheme zookeeper!)

i've painted in vocational many times and one problem i have is tring to make the base coat shine. It should not shine, it should look very dull. as far as sanding between the primer and base, i use 500 grit. once you go over it, if you have any high or low spots, the dust from the sanding will make them more visable. for sanding between clears, im not 100% sure on this. somewhere in the 1000 to 2000 grit range.

 

[mustbereel]

sanding again

Hi Cobain03,

You've got a pony car in a horse town!

Thanks for the info. Your car looks great!

Brad

 

[Cobain03]

no problem. and to be honest, if you are not being rushed into finishing it. to do it yourself is the best way. if you get a run, jsut sand her down and try again. depending on the amount of imperfections, you could become good!

 

[67GTA-FB429]

additional question...

when sanding the car with the glass out, how do you keep from getting water in the interior?? or have you gutted the car and don't care?

 

[NasaGT]

A good way to get even coverage on metallics and pearls is to hold the gun a bit farther away (7 inches or so) overlap your passes by 50% and use light coats. Don't try to "wet" base coats with a basecoat/clearcoat system or you'll have blotches (blotches? We don't need no stinkin' blotches!) Sorry, I couldn't resist. Anyway, the rule of thumb for bc/cc paints is to just get even coverage with the color and just worry about making it shiny without runs with the clear. Modern metallics are much easier to shoot than older, single stage metallics ever hoped to be, you'll be fine.

Very good advice here.

I personally only block with 400 and 600 after all body work is done and several coats of primer are down.

 

[mustbereel]

interior

Hi 67GTA-FB429,

I can't help you with the water issue. My interior is gutted. Nothing but a shell right now.

Brad

 

[Cobain03]

i really suggest that you gut the interior. on these older cars, there are alot of cracks and crevases that dust,paint, and water can seep into. at the very least i would take the carpet out and cover the seats with a bag or something.

 

[67GTA-FB429]

more worried about the dash. the seats are out, carpet is easy to remove.

 

[zookeeper]

As far as keeping water out of the interior, specifically the dash, I'd just mask off the window areas to seal the interior off from dust, water, etc. You won't be using all that much water anyway and some masking paper is a bit "waxy" anyway, so it'll repel small amounts of water. To wet the area I'm wet sanding, I use a small sponge, held near the area, and kind of squeeze out some water as you need it. Some guys use squirt bottles, but the point is, you really don't need much water so the chance of damage to the interior or dash is fairly small. Of course you need to remask after any sanding, because the spray gun pressure will blow any sanding debris out of the paper and into your paintjob. As far as sanding in between clear coats, here's what I've been told: there are two kinds of ways for paint (or clear) to adhere to a surface, chemical and mechanical. A chemical bond is created when you spray clear, for example, over fresh base. As long as the base has been sprayed before it fully cures (usually within 24 hrs) a chemical bond is created when the clear solvents "bite" into the base color. A mechanical bond is created (and is necessary) when, for instance you are spraying base over cured primer, or are re-clearing a car or panel. Because the substrate (primer or clear you are spraying over) is cured, the product you are shooting cannot adhere to the slick surface, so you need to sand the part you are spraying over to create little grooves for the paint to stick to. The bigger the scratches, the better the adhesion, but in order to hide the scratches, they need to be done with paper between 400 and 600 grit. Any coarser and you will see sanding marks, much finer and the paint won't stick. I know one local painter that uses 800 grit when re-clearing over artwork and sometimes he gets away with it and sometimes he doesn't. When I recleared my car after the stripes, I used 500 grit, and even though there's a lot of very fine metallic in the blue stripes, you can't see even one sanding scratch out in the sun, so why would I use finer paper and risk having the clear peel next year? Also, for tight areas, like door jambs, rain gutters and the engine compartment, I use gray 3M scuff pads to knock the shine off the panel. You can imagine how easy it is to sand right through the clear when you hit a spot weld or an edge in the engine compartment or door jamb. Also, I use a water-based post sanding cleaner before any painting session and really believe it not only cleans the area, but helps adhesion. Solvent-based cleaners can leave residue which could cause fisheyes later.

 

[67GTA-FB429]

Thanks. Probably just being overly nervous.