[67LS1T56]

I'm getting allmost ready to block sand the 2K primer. What grit would you guys start with and dry or wet? Should I start 220 then 400 and 600 dry
Or
can I 400 dry and 600 wet. Whats the right steps?
Thanks

[Rick WI]

I long board 2K at first with either 120 or 180 dry. I'll continue to long board block a panel with each new coat of 2K until the surface is flat. After the first coat is sanded if the panel is pretty close I will always use 180. After final with 180 I recoat with 2K and block with 400 then final with 600 wet, inspecting the panel after wiping down with wax and grease remover as I go. I wipe the panel with wax and grease remover and leave the surface wet and shiny looking for imperfections and waves as I sight down the panel.

[baddbob]

Your starting grit is dictated by how bad the imperfections are that you're trying to remove. If you've got some major waves 120-180 would be the grit to use, if she's basically straight with just some light ripples or texture then 220 would work, If it's straight and just needs to be smoothed then start with 400, reguardless how bad the defects are and what grit you start with definately finish with 600. If you've got a lot of primer on and start with a heavy grit with out cutting through- you can then apply more guidecoat and step down to a finer grit. Definately use a guidecoat. You can wetsand or drysand, I prefer drysanding with the coarse grits but final sand wet- it can be done either wet or dry, Bob

[nick62877]

yep , i like to go dry with the coarser grits , and finish up wet with anywhere between 500-800 . for me , the final grit will be chosen depending on the metallic flake or if i'm going to use a clear ground coat before i start basecoating. the finer grits just seem to clog up way too fast if you use them dry.

[Bee4Me]

Guide coat is a MUST for straightness. I use lacquer primer for a GUIDE coat at it's cheap and dries fast. 3M's dry guide coat is great as well.Flat black is good for the cheap guide but any spray bomb enamel will just clog your paper up faster.
I use up to 180 dry and above that,wet as like said,the finer grit's clog fast dry. I use a gray Scotch pad wet last, lightly going over the whole thing to catch any missed sand scratch's and blemish's.

[302 Z28]

Yep, I like the 3M dry guide coat, but I almost had a cardiac when I bought it and saw how much it cost. At least it goes a very long way, enough for probably a dozen or more cars. It better last a long time at $38.

Vince

[staircasesurfer]

i have found that a spraybomb "sandable Primer" (as noted on the can) works well, its cheep at 2-3 dollars a can, plus cleanup is a snap, a quick toss in the trash

just lightly mist it on, i used about 1 1/2 cans doing my 72 skylark

i started blocking my polyprimer with 220 and found it took alot of work, so i started using 180 dry and it works better, to get it straight, i will go over the 180 with 320 dry, then 400 dry/wet? not sure yet, and finaly 600 wet.

hope this helps

[baddbob]

Originally Posted by 302/Z28

Yep, I like the 3M dry guide coat, but I almost had a cardiac when I bought it and saw how much it cost. At least it goes a very long way, enough for probably a dozen or more cars. It better last a long time at $38.

Vince

Yeah, the price is ridiculous, my cost on the refill is like 25$ and it only lasts me through one complete restoration, I try and use elcheapo laquer primer as much as possible but the dry guidecoat works great and is easier when your just stepping down to a finer grit and don't want to mask for spray type guide coat.

[Bee4Me]

I've been tempted to try chalkline chalk. I was looking at it and thinking "HUMMMM????" I don't know "IF" or "How Much" wax or such is in it,but I use regular stick chalk (wax free) for layout's. This may not even be a viable alternative (dumb idea). Just been rumbling around in the back of my head.
3M's dry guide is "sort" of a chalk (powder) and I was curious if anyone had used chalk of some sort.

[Rosewood]

I believe dry guide coat is a graphite, but the chalk sounds interesting. Maybe some test panels would give an answer.

[jcclark]

I also use the sandable primer in a rattle can, I think it works great but
I just mist it on, it doesn't take much.
I use to add a little black acrylic enamel to my gun before making my last
pass with primer, my 2k is yellow and just a little black in the cup would
mist a darker color for the last fast pass. That works good, it may not be
the best for compatibility but I always sand every bit of it off.
Some old timers would take a pencil and wipe it accross the primer panel
leaving lines everywhere then sand until they're gone. Woodworkers
do the same to glued up panels, The graphite doesn't seem to be a
problem and it stays on when you're wet sanding.
I now have two different colors of primer by the same mfg, I may
start mixing a little of one into the other for the last coat.
There's lots of ways for doing a guide coat, they sure do help me
and I wouldn't do any repair work without using one.

[baddbob]

Originally Posted by Bee4Me

I've been tempted to try chalkline chalk. I was looking at it and thinking "HUMMMM????" I don't know "IF" or "How Much" wax or such is in it,but I use regular stick chalk (wax free) for layout's. This may not even be a viable alternative (dumb idea). Just been rumbling around in the back of my head.
3M's dry guide is "sort" of a chalk (powder) and I was curious if anyone had used chalk of some sort.

I think you're on the right track, chalk line powder might work, some kind of drawing charcoal might also work, 3M must have a patent on it-surprised no other company has offered something similar.