Block sanding question

[Charger-Bodie]

Mainstream body shops dont seem to grasp the benifits of Poly surfacer on a resto project. Epoxy it,the poly surfacer. Make sure the epoxy is dried thuroughly though before sparaying poly.

[AirborneSilva]

I've been following this thread and I gotta say I appreciate all the helpful tips and advice.  I hope to start doing panels on my Charger fairly soon.  Thanks again guys 

[E5 Charger]

I love this thread. It's great to hear from painters that work with the stuff, instead of salesman selling it. One question, how long can a panel sprayed with epoxy primer sit without paint before rust would set in?

[bill440rt]

I love this thread. It's great to hear from painters that work with the stuff, instead of salesman selling it. One question, how long can a panel sprayed with epoxy primer sit without paint before rust would set in?

It depends what elements it is exposed to. In a dry garage, probably a very long time. Sitting out in the driveway, not so long.
My car sat for almost a year while I was doing body work on it in epoxy primer, but it was in a garage.

[E5 Charger]

It's in a garage. Good to know, thanks.

[elitecustombody]

I love this thread. It's great to hear from painters that work with the stuff, instead of salesman selling it. One question, how long can a panel sprayed with epoxy primer sit without paint before rust would set in?

It could take few years depending on how thick epoxy was sprayed for rust to start and mostly on sharp corners and edges that are prone to wear .But whatever you do,make sure your air supply is dry when applying epoxy on bare metal.

[Dino]

This may have been mentioned but at this time I'm way too lazy to read three pages.   

When sadning, be it by hand or machine, never ever put more pressure on the panel thatn you have to.  Let the sandpaper do the work.
I mention this because I used to train the newcomers in the shop and every single one of them pushed down fairly hard on the block or da sander, or a sheet of sandpaper for that matter and it's a bad habit to correct.
This is a problem especially on the newer cars which have flimsy sheet metal, a Charger is more like sanding a tank but still, keep it light and keep it moving.   

[1BAD68]

Got a question...
On the upper quarter above the wheel well, I can feel a dip in the panel (see picture, red line is exaggerated).
I've been using my 16" wood block but am I better off using a flexible block. The wood block doesn't seem to be working due to the curves running vertical and horizontal or am I doing it wrong?



This is the block I'm using

[AmadeusCharger500]

are you using the block side to side using the 2.5 inch path or up down using the 11 inch path? I did it wrong way for so long I was slightly embarrassed at myself.

[Dino]

Got a question...
On the upper quarter above the wheel well, I can feel a dip in the panel (see picture, red line is exaggerated).
I've been using my 16" wood block but am I better off using a flexible block. The wood block doesn't seem to be working due to the curves running vertical and horizontal or am I doing it wrong?



This is the block I'm using

Both blocks work but the flexible will be a bit more forgiving.  Try to do an x pattern as much as possible and again do not press down on the block anymore than you have to.  Don't sand back to front, go from upper left to lower right, then from upper right to lower left and get a groove going.  Also make sure to sand well outside the filler area.  You don't want to simply sand the filler spot alone, you want to blend it in with the rest of the panel.

[1BAD68]

Yup I've been working a X pattern and it has worked great everywhere but this spot.
Maybe I just need to build it up more and then work it down?

[73rallye440magnum]

That looks like a pretty sturdy wood block. If you're not careful you'll end up with flat spots. I like to use balsa wood. It's very flexible.

With a flexible block, rotate your sanding pattern 90 degrees, so the long part of the block is perpendicular to the floor. Sometime that helps block out the stubborn ones.

[Dino]

Yup I've been working a X pattern and it has worked great everywhere but this spot.

Looks good but I have a question.  Do you know what's under the filler?  Did you apply it?  Just wondering because if you still feel a dip it means the dent is probably still there, ie it's too deep to cover with filler.  If so I would remove the filler and work the metal a bit more.  If you can't get the panel straight with a few skim coats it means it needs more metal work.  If for whatever reason you cannot get the metal straight and you need more than 1/8" of filler then get some metal to metal type filler as it will hold up much better than the finish filler you're using.  Use a metal filler to fill the dents and the white finish filler on top of that, very thin skim coats.  Preference would be getting the metal straight though.

[1BAD68]

Yes I applied it and it's very thin right now, I'm guessing but right now it's about 1/32 of an inch maybe 1/16 at most. I thought I would probably make it worse pounding on it from inside.
Actually you can't feel it when running your hand horizontally, only when feeling up and down it's noticeable.
I'd probably just leave it alone because I'm not shooting for a perfect show finish, but this is in a extremely visible area.

[Dino]

It's very thin right now and actually you can't feel it when running your hand horizontally, only when feeling up and down it's noticeable.
I'm guessing but right now the filler is about 1/32 of an inch maybe 1/16 at most.
Probably would just leave it alone because I'm not shooting for a perfect show finish, but this is in a extremely visible area.

Fair enough.
You may be feeling the wheel well lip on the quarter, the metal might be slightly stretched.  Keep sanding as you do and ignore that dip.  It may seem strange but it will tell you exactly how deep it is when everything else feels okay.  After you fix the dip, be it with more filler or a few taps with a hammer (it may not be an inward dent but an outward dent) you can skim coat it again and when you do make it so that you cover the entire area again.  Never do small filler spots, always go way bigger so you can keep the filler thin and perfectly feathered at the edges.

I hope I am making sense, it's really hard to explain.

[1BAD68]

Ok I had a breakthrough.
Using some old rubber snap together floor tile (the kind of stuff you see in kids play area's) I cut two strips and glued them together kind of like a Durablock.
Anyway's it worked 100% better on that problem area than my wood block which was basically a piece of oak from my kitchen remodel.



This also works great on really curved area's like the sail panel.
It bends just enough but not enough to be flimsy. I think I'll just go over the whole car again with this and see what happens.
I saw a Durablock this size at the paint store but thought I could get by without it. I guess they make them for a reason.

[Dino]

Good job!   

If you like that then try this, get several sizes of rubber hose and wrap some sandpaper around it, instant all shapes, all sizes sander!  Semi rigid hose about the size of a radiator hose is perfect for those self stick longblock sandpaper sheets.  Get one small enough and you'll have the perfect sander for tricky spots like the connection between inner sail panels and dutchman panel.

[NHCharger]

Thanks for the replies Stefan and Bill
I stopped by and saw my body guy on Saturday. I told him I was conversing with you guys on body work and the majority here recommended epoxy primer first, then any filler followed by poly sealer. He said there's ten different ways to skin a cat. He's been doing body work for 30+ years, the last 20 he's owned his own shop, 90% of his work is restorations. He still recommends doing the body work and filler on bare metal. If my shop had any moisture issues (which it doesn't), he said he would epoxy prime first. He claims the only problems he's had has been customers not wanting to strip their cars to bare metal and wanting him to paint over the old paint. He stopped doing that years ago when he had a problem with "lifting" on a couple of cars.

I guess at this point I will continue to do it his way. He told me that if I was uneasy about doing the final base/clear application he would come over to my shop and do the finish paint for me. That sounded real good to me since I am real apprehensive about that stage.

[Patronus]

My favorite it the dura-block 1-3/8"x11" block-one end to the other-both straight and arched to the body. Over, and over, and over.....

[AirborneSilva]

Good job!   

If you like that then try this, get several sizes of rubber hose and wrap some sandpaper around it, instant all shapes, all sizes sander!  Semi rigid hose about the size of a radiator hose is perfect for those self stick longblock sandpaper sheets.  Get one small enough and you'll have the perfect sander for tricky spots like the connection between inner sail panels and dutchman panel.

That's a great idea Dino, I'm gonna have to go to the auto store and get me some straight radiator hose.  I'll also use 1Bad68's idea too...  Thanks guys 

[1BAD68]

Yeah thats a great idea, I tried some scrap hose laying around and it worked great 
Had another breakthrough.
This stuff I've been using called "glaze" that comes in sort of a tube like bottle and mixes with hardener would go on really thick, like filler out of the can and then take almost 24 hours to dry enough that it wouldn't plug up my sand paper.
It's suppose to be thin enough to fill scratches and very slight dings.
Basically I was putting it on and waiting till next day, then sand 95% of it off.
Then I found out that all these products have "batch numbers" which show the date they were made. turn's out the tube of glaze was from 2004!! (I just bought this from the paint shop last month)
Needless to say, I won't be buying from there anymore or taking there advice.
Found a different place and bought some "icing". It spreads really nice like warm butter and was ready to sand in 30 minutes without clogging my paper. This is making my life much easier, I got more done in two days with this stuff than I did in two weeks with the other crap.

[1BAD68]

After icing and blocking many many times I figure I'm at the stage where I can use some poly primer.
Go to the new paint place and they don't recommend using slick sand unless it's for fiberglass, like a corvette body even though they have it on the shelf.
But they recommended this stuff by Sherwin Williams called "Finish 1" its a DTM high build, I figured I'm done messing around and just bought a quart to try it.

It works pretty good and after reading about how the Evercoat stuff sets up really fast and can harden in the gun if you're not quick enough, I noticed this stuff was more like mixing and spraying regular primer.
I mixed up half a quart because I only wanted to spray the sides of my Charger, had some issues with my gun so it took way longer than I thought (almost 20 minutes to spray both sides) and sprayed two coats on each side but had no problems with it setting up in the gun.
Each coat is thin maybe somewhere around 2 mils so I ended up with about 4 mils per side but I spent so much time on this car already that this worked fine.
About 4 hours later I knocked it down with 120 grit which went very fast, probably could use 180-220 but I'm going to do this one or two more times with a final 400 grit sanding before sealer.

[Dino]

Priority 1:  Fix the gun so you can spray a light coat followed by 2 wet coats.  If it feels like you're spraying more air than primer it's going to bite you in the butt when it comes time to prep for topcoat.

What gun is it?

[AirborneSilva]

  If it feels like you're spraying more air than primer it's going to bite you in the butt when it comes time to prep for topcoat.

Please explain.....

[Dino]

  If it feels like you're spraying more air than primer it's going to bite you in the butt when it comes time to prep for topcoat.

Please explain.....

The paint will come out coarse, almost gritty.  With a well working gun and the right paint viscosity you have full control over the thickness you want in a coat, you'll have good flow and you'll have normal gassing where the solvents evaporate.
When you have a lot of air but not a lot of paint come out it'll not only take a while to build up the paint to a sufficient thickness, it will also be a ton of dry coats instead of 2 or 3 wet flowing coats.  You lose adhesion between layers for one because in effect the last coat your spraying over is not sticky, but the real trouble is that you can end up with pinholes in the paint. 

If you spray a nice wet coat on a body panel and let it dry, it's very smooth and all is filled. With dry coats you don't get that, you may have to sand and reprimer several times for it to be a good sealing base to put your topcoat on.

I've seen too many people simply paint over the thin perforated primer and you can pick those out real easy a few weeks after because the topcoat as sagged into those pores and it looks pretty bad.

As with everything, you need to build up thin, wet layers.  A bad spraying gun is usually an easy, cheap fix but it's sometimes easier to ignore it and make the best of it, I've done it myself many years ago and paid the price.  The reason I try to help people with bodywork here is because I know what can go wrong and how to evade it.  It's hard enough as it is so if I can prevent people from making the same mistakes we all did then I'm glad.