High build primer and block sanding
 

So I have just finished block sanding my bed side that has 2k urethane primer on it. I have a few low spots that still need some attention. Do I spray more primer over the entire panel, or just on the low spots? How should I prep the low spots that haven't been sanded, gently sand only in the area so I don't make the low spot bigger?

Re: High build primer and block sanding
 

You do not want to use primer to fill too much! If you have a low spot, it really depends now low. Is the paper hitting the bottom of the low spot? If it's not, DO NOT try to fill it with primer, you are asking way too much of the primer. Fill it with polyester putty and reprime.

You can spot prime the areas but overall on the last coats after you have blocked is always the best.

But don't try to fill too much, the primer should be limited to very minor differences with the filler and surrounding metal and sand scratches in the filler, that sort of thing. It's not to straighten out a dented panel.

Brian

Re: High build primer and block sanding
 

No dents or dings remaining, but I hit the lower coats and metal around a few areas before all of my guide coat was off.

Re: High build primer and block sanding
 

Typically the filler / glaze step has your panel closer to flat and straight if you sand through all your primer. Primer is so very expensive and like Brian said, not meant for thickness. Perhaps more body work is in order in the low areas before more Primer is applied.

Think of it this way... hammer and dolly, filler, glaze, Primer... each step getting closer to paint as the process gets finer and finer...can't skip any step.

Re: High build primer and block sanding
 

If you hit metal and guide coat is still there, that is too much to fill with primer.

But listen, it really depends on where it's at, it depends on your expectations, it depends on a lot of factors if you want to correct this fully or just "get-r-dun" there is a little to think about here.

A newbe could over do this where it just doesn't matter, a rounded area on a fender or something like that, a little low spot won't be noticed and maybe not even seen at all if you wanted to.

Where as if this is in the middle of the door and depending on the color you are painting it, it could stand out like bullet hole.

If you shot a photo of these areas that may help. Another application of primer may be "good enough" where it will almost be gone even though you may hit that metal again while sanding before the guide coat is completely gone and it will without a doubt be good enough. It's hard to say, can you post a photo?

It's not like it's a real big deal understand, unless you are applying way to much primer and it's got solvent entrapment, it's not a real big deal. I am just going over this stuff so you have a better idea of how to attack each of these types of things when you come across them. And as Stomper said, all it takes is to finish off the filler properly and there is nothing to think about.

Brian

Re: High build primer and block sanding
 

I am definitely a newb (first time) and I have a history of over doing things. My goal is a good looking driver. I still drive this truck to the dump and the hardware store, as well as the occasional car show.

The finish will be a solid satin. I'm actually plastidipping the truck. I have two little boys that I share the garage with, so a paint job will be wrecked quickly. I won't feel as bad if it's damaged with a temporary coating. The plan is to get the body work finished, top coat with epoxy primer and wet sand for a smooth finish before the plastidip.

Re: High build primer and block sanding
 

Plastidip will turn to a permanent coating in a short time and then you will have a hell of a mess on your hands. Why not just get a gallon of Alkyd Enamel from Rustoleum and spray it with that instead? You can get a satin finish and have a durable enough runner for a fraction of the cost too. Just a thought...

A better than Alkyd Enamel (air dry paint) would be a urethane that be even better... just saying.:metal:

Re: High build primer and block sanding
 

And if that is the finish you are after, I wouldn't worry about those little low spots.

Get it painted and drive it with a smile on your face! :metal:

Brian

Re: High build primer and block sanding
 

This is where the bedside is now. Tried a trick I saw online by wetting the surface with solvent and looking at the reflection of the light to see if it bent funky. Good news is I didn't see anything super crazy, bad news is I didn't think to mark the low spots and the guide coat came off with the solvent.

Re: High build primer and block sanding
 

Realistically you are going to need to prime that whole panel anyway. Apply four coats leaving a lot of flash time and get her ready for paint!


Brian

Re: High build primer and block sanding
 

The satin is very forgiving compared to a glossy finish.

Re: High build primer and block sanding
 

for reference: you do NOT want to spray Plasti-Dip over bare primer.

Re: High build primer and block sanding
 

That's what I thought too, just trying to decide between more high build urethane or epoxy

Re: High build primer and block sanding
 

Im guessing that the urethane (is that the same as acrylic urethane?) will be easier to paint over if and when I paint the truck with real paint?

Re: High build primer and block sanding
 

You're 100% correct!!

A paint that requires an activator is a fantastic product because it's more durable and is a very stable product to scuff and paint to repair blemishes and boo boos.

Re: High build primer and block sanding
 

I know all of these products need time to cure before something goes over them, how long would I need to wait before I go over top of the urethane paint with plastidip?

Re: High build primer and block sanding
 

I'm missing your point in using plastic dip at All? I know what plasti dip is too.
You're right that new paint gasses off but I don't know about a safe time interval.

Why not just paint it the colour you want in the first place?

Not being rude....just confused.

Re: High build primer and block sanding
 

No worries, I didn't take it as rude. I know you are probably familiar with plastidip, but for anyone that comes across this thread that isn't, I'm not talking about spray cans of flat black from the auto parts store or canisters to re-do a screwdriver handle from the home center. This is real spray equipment and gallons of sprayable product formulated to be a removable automotive coating.

The point in using plastidip is for paint protection (2 little boys with lots of toys and bicycles in the same garage as the truck), the versatility and low cost to change colors, designs, etc., the opportunity to do something different but not permanent (in case it's a disaster), and lastly (and probably most important) I'm still not sure what I want for a final paint scheme or design!

This is a truck that I plan to keep around for a long time. A truck that hopefully my boys will learn to wrench on and if they are truly interested, maybe a truck we can paint together (maybe I will have it figured out by then).

Re: High build primer and block sanding
 

I'm with Foot Stomper on this one and wondering why not put on paint before using the plastidip. The primer is going to have a porous surface and if/when your plastidip gets nicked or scratched it's going to be a conduit for water to start soaking into the primer beneath it. Also how hard is it going to be to remove your plastidip when you get ready to redo it or change the color?

Good luck,
Charles.

Re: High build primer and block sanding
 

That is actually the part I am working on now, doing the research on highly sanded primer vs. a color coat. I have no preference really, both will require materials and time. My main concern is doing things in a way that make the plastidip peelable and keep the surface below in a state that is safe and can be painted over in the future. At this stage, I am leaning heavily toward coating in paint and then going plastidip after the paint has cured.

Re: High build primer and block sanding
 

how about this? its what I'm doing. basecoat the color you want and a flattend clear? forgiving to less than perfect bodywork, easily repairable, you don't have to buff it (or it will get shiny and defeat the purpose) and good starting place for us novice painters. use lower end base coat I'm using Omni ppg. and some sort of flattened clear with uv protection. you can pay from 100 to 4oo+ for clear so define your needs and enjoy the ride. If your truck will remain inside and not live a hard life or live on salted roads weigh this in your decision.
enjoy it!

Re: High build primer and block sanding
 

Just a progress update. Entire truck is in primer now. Time to sand some more!

Re: High build primer and block sanding
 

lots of good solid advice on this thread, your like me going to keep asking until I get the answer I want... and then proceed :)