Ok here's the deal I am not rookie, been doing body and paint off and on for 20+ years (damn I'm getting old). Of course back when I learned we only used laquer primers, etc... so you didn't get the build that these newer products offer.

My question is how big of a step are you guys taking in paper grit? Meaning are you blocking with 180 and then just hopping to 400 after a re-prime? I am blocking my car with 180 right now (polyesther primer over Epoxy) and I don't want to waste time and materials using my "old school" practices (this stuff isn't cheap and every coat sets you back 24hrs (urethane and epoxy)).

My normal practice would be to go 180 - 220 - 320 - 400 wet and then spray color. I have been reading where guys are now going to 600 before spraying color. This will be a bc/cc dark blue metallic so I think going 600 will be the best thing to do.

My final primer/sealer will be epoxy (SPI) primer. I am only blocking to 180 with the polyesther and then I will use urethane for final blocking. all blocking will done done dry until my final sanding before paint, then I will wet sand.

I know there will be several differnt opinions/procedures and that's exactly what I want to hear. I have used the newer stuff (epoxy, urethane, etc...) on several projects and had great success but, I am always willing to learn a new or better way.

The way this stuff fills I swear it seems like I could go from 180 to 400 and not have any scratches.

All tips and pointers are welcome. Sorry for the long read but, I wanted to be clear.

i usually go 180, 240, then 400 wet. if posible set the car out in the sun to bake before each sanding.

I'm a commission auto painter of 15 years. Block out with 180 paper then prime at least three coats of a good brand of urethane primer. Don't go cheep on the brand because you could pay down the road with sand scratches showing up. Let dry(Sitting in the sun for awile would be fine) 400 sand paper would be great for your final sand. This is the best way to cut out anymore unneeded steps. Before you paint your car you can use a sealer to cover bare metal areas. If this is not taken care of your paint will not stick down the road.

Thanks for the input. I would never leave bare metal areas but, that's a good point. I am using all SPI products other than the Feather Fill G2. I just read up on the SPI 2K primer and is says it will fill 80 grit scratches in one coat. I will apply 3 coats and block it out with 400 dry. I will seal with SPI Epoxy primer and wet sand that to what ever the paint manufature suggests (usually 400 or 600).

This is really going to make things a lot faster, easier, and cheaper.

Epoxy primer can be used as a sealer. I know some brands of epoxy you have a seven day window as a wet on wet(no sanding needed) Check with a paint rep of the product your going to use. To get the epoxy to lay down with little orange peel you can reduce 5 to 10 % with reducer. Be carefull not to run your sealer. Even if your 2k primer says that you can prime over 80 grit and ready for paint is very old school. This can cause rings around areas of body filler and scratches showing up later.

I think you mis-understood me. It just says it will fill 80 grit scratches in 1 coat. It is just giving you an idea of the mils per coat. I would never try to go from 80 grit to paint in one step. I hate sanding scratches so I put in the extra effort and time to make sure everything is right. I just don't want to do more work than is needed or waste materials.

I do not want to paint wet on wet, I want to wet sand my Epoxy/sealer and let it sit for a while before I top coat it. I will be adding a bit of urethane reducer to the last coats of Epoxy.



The weather has been very warm here and I let everything sit in the sun to dry and after I sand it.

I blocked with 180 primed and reblocked with 180 several times till it was as flat as could be then blocked with 320 and sprayed nonsanding sealer and let it sit for a week.I then blocked with 320 the hand sanded with 600 backed by a scotch bright as a sanding block this was to assure no shrinking.But all this was done to my car, for a customer you have to give what they pay for and govern this buy the amount of bodywork and how straight they want the car.

Royce,

Are we having fun yet. LOL Have you checked out these sanding blocks. I bought a set and they are great, especially the long one. They have 3 rods in the end of them that are removable which makes it so the board will bend to the contour of the panel. Eastwood sells them but they are cheaper on ebay. They have a metal plate on the bottom of them so sticky 2-1/2" sandpaper will stick to them.

http://cgi.ebay.com/Set-of-5-FLEXIBLE-LONG-BOARD-SANDER-SANDING-BLOCKS-AUTO_W0QQitemZ190250941281QQcmdZViewItem?hash=item 190250941281&_trkparms=72%3A1163%7C39%3A1%7C66%3A2%7C65%3A12%7C 240%3A1318&_trksid=p3286.c0.m14

http://i268.photobucket.com/albums/jj16/prostreet69camaro/SandingBlocks.jpg

I usually enjoy block sanding, it's kind of relaxing. This car is a different beast, there are no flat panels, everything has a body line, curve, peak, or something. Just makes for longer blocking time. I have all kinds of sanding "blocks" (round, long, short, pointed, etc...). I have seen the blocks posted above but, have never tried them.
They do look nice and I bet they work great if you have large areas to block. This car doesn't have enough large areas so getting a longer block won't help me.

I do all my blocking with a guide coat so as long and I read it correctly it should be straight and flat after I get done with the 180, frrom that point on it's just about getting rid of the sanding scratches and keeping it flat.

I usually enjoy block sanding, it's kind of relaxing. This car is a different beast, there are no flat panels, everything has a body line, curve, peak, or something. Just makes for longer blocking time.

I do all my blocking with a guide coat.....

Man, do I hear you on that one! There's almost nothing that's flat. It's beginning to become a real cumbersome pain in the butt. I was excited to get the body work done and shoot primer but I didn't realize how tough smoothing this big, curvy beast would be.

What do you shoot as a guide coat Royce?

I have a question about filler? Does anyone here put filler directly on bare metal? Aren't you supposed to coat metal with primer then appy filler?

Man, do I hear you on that one! There's almost nothing that's flat. It's beginning to become a real cumbersome pain in the butt. I was excited to get the body work done and shoot primer but I didn't realize how tough smoothing this big, curvy beast would be.

What do you shoot as a guide coat Royce?

Joe,
I will trade you block sanding duties any day. I've done Camaros, VW Beetles, etc.. before and while they are rounder they still have large surfaces to work with. This 1961 Buick Skylark has so many angles and curves, and in many place both features (angle and curves) join together. Block sanding is block sanding but, on a car like this you have to break each panel down into little sections. There are few areas where I can actually take long strokes. Hard to explain, I'll take a couple pictures when I roll it outside today.

Hang in there block sanding is just one step closer to paint.

I have a question about filler? Does anyone here put filler directly on bare metal? Aren't you supposed to coat metal with primer then appy filler?

The only fillers I have seen recommend for bare metal are "Metal to Metal" and "All Metal" which are aluminized filters. Even then I've seen claims that this is not a good idea. Standard fillers absorb water because of the talc in them and should never be applied to bare metal. I've got a 64 GTO that had filler applied to bare metal years ago and it is a rusty mess under that filler. Bare metal should be coated with two coats of epoxy primer before applying filler.

That being said, why would anyone want to take the risk and apply filler to bare metal when all it takes is a couple of coats of epoxy for insurance?

Don

I have a question about filler? Does anyone here put filler directly on bare metal? Aren't you supposed to coat metal with primer then appy filler?

You just had to go and ask that question. You will never get everyone to agree on this. When I took my body shop classes (20+ years ago) we were taught to grind to bare metal (with 36 grit discs) and apply body filler over that. Many people still do it that way. These days a lot of people prefer to fill over epoxy primer. I won't tell you which way is the "best" because I don't know if there is any way to prove it. The old primers were not nearly as good as the epoxy stuff we have today so I don't have a problem applying filler over it. I would never apply filler over laquer primer but, not many people still use laquer primer that I'm aware of.

The arguement that will be presented is that if you fill over bare metal, rust can develop under the filler. I have never seen this happen and I have stripped off old body filler from project cars I bought and never found any rust. To form rust you need two things, moisture and oxygen. If you seal all your work and paint it where is the moisture and oxygen going to come from? The only time I have seen rust under body filler is when the area was damaged and the filler was cracked.

Either way works fine if done correctly, you have to decide which is best for YOU. I have done it both ways and the results are the same.

I've always thought you filled over primer.

Stepping back a process or two, here's a blocking question for the filler work you've done on a big panel like a quarter or deck lid..... say there's several small low spots close to each other in the panel and you've filled them with your favorite goop, whatever it might be. Using my longest sanding block (a 12" Motor-Gard Big Block), I try to sand by holding the block length-wise across the filler in diagonal directions, then straight across the filled spots so that they'll blend in to the metal. I rarely hold the block by it's ends and run it up and down across the filler.

I have a bunch of low spots all in a straight row at the top side edge of a quarter panel before it rolls over. I filled all of the low spots and when I block sanded them, I ended up with a couple areas of metal between them that ended up being HIGH! I ran the block across them length-wise, from front to back of the panel, and diagonally, holding the block length-wise. I can't for the life of me figure out how the filler could have gotten sanded lower than the panel. The rest of the filled low spots blended in just fine.
I had the same thing happen in an area of the deck lid. No matter which direction I hold the block, or which direction I sand, I always seem to end up with a high spot in the panel. Am I not spreading enough filler (I know I am)? Am I heating the panel up to the point that it warps?
The only explanation I can think of is that the high spots in the panel were there before I did the filler work and blocked. I suppose I can take a closer look and maybe level them out before smoothing some more filler on and blocking it.
Is that my problem?

I've always thought you filled over primer.

Stepping back a process or two, here's a blocking question for the filler work you've done on a big panel like a quarter or deck lid..... say there's several small low spots close to each other in the panel and you've filled them with your favorite goop, whatever it might be. Using my longest sanding block (a 12" Motor-Gard Big Block), I try to sand by holding the block length-wise across the filler in diagonal directions, then straight across the filled spots so that they'll blend in to the metal. I rarely hold the block by it's ends and run it up and down across the filler.

I have a bunch of low spots all in a straight row at the top side edge of a quarter panel before it rolls over. I filled all of the low spots and when I block sanded them, I ended up with a couple areas of metal between them that ended up being HIGH! I ran the block across them length-wise, from front to back of the panel, and diagonally, holding the block length-wise. I can't for the life of me figure out how the filler could have gotten sanded lower than the panel. The rest of the filled low spots blended in just fine.
I had the same thing happen in an area of the deck lid. No matter which direction I hold the block, or which direction I sand, I always seem to end up with a high spot in the panel. Am I not spreading enough filler (I know I am)? Am I heating the panel up to the point that it warps?
The only explanation I can think of is that the high spots in the panel were there before I did the filler work and blocked. I suppose I can take a closer look and maybe level them out before smoothing some more filler on and blocking it.
Is that my problem?


Joe,
Are you using a guide coat? Sorry I missed that question in your ealier post. I am using 3M Dry Guide Coat. Works great.

The problem you're having is because the high spots are already there so, the metal gets exposed before the filler is feather edged. If there is only one area of metal that pops out but everything around it is still covered, that area of metal has to be high. If it is a flat area take a flat edge and stick it on ther in different angles. When you are block sanding make sure you are hitting everything from different angles son't sand back and forth in one direction to many times, always try to sand in an X pattern.

I got a question. My car was painted 11 months ago and its back in the paint shop to re-paint the hood... My question is with a Orange solid color is it worth sanding with 3000 grid... The reason for my question is they wet block sanded the hole car with 3000 grid and said this will help it lay down flatter and its easier to polish.
Thanks guys.

Skip,If you sand with 3000 only you will have an adhesion problem.I think 800 max on just about color or product jmo.

Joe,block sanding bodywork if you sand with to fine of sandpaper before you get the mill thickness will some time have this effect even on the slightest high spot in the metal.And if you do find this after priming I would say you need to pull a thin coat of metal glaze and block with 80 if you see metal at any point stop nand reaply.Then go to primer over the 80 and then block with 180.Everybody has there certain steps this is mine....JMO>>>>

I agree with Dave, 3000 is way to fine to spray over. The only way it is going to work is if a chemical bond in formed. Since the paint is fresh this may be what they are counting on.

Skip,If you sand with 3000 only you will have an adhesion problem.I think 800 max on just about color or product jmo.

Joe,block sanding bodywork if you sand with to fine of sandpaper before you get the mill thickness will some time have this effect even on the slightest high spot in the metal.And if you do find this after priming I would say you need to pull a thin coat of metal glaze and block with 80 if you see metal at any point stop nand reaply.Then go to primer over the 80 and then block with 180.Everybody has there certain steps this is mine....JMO>>>>WOW Guys im sorry, i meant to say that the body shop is wet sanding/color sanding with 3000 grid on the clear coats before buffing it out again... Ill be picking the car up on Tuesday, i cant wait. Didn't mean to hi-jack this thread :beers:.

Thanks for the input about primer over filler or the other way around! I appreciate it!