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Old 04-23-2012, 01:20 AM
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What's the secret/trick to skim coating panels

It sounds like your skimming techniques are OK. It could be that your problem is not narrow low spots - they are actually a highs in the sheet metal. It could be that the metal is stretched and it needs to be dealt with before applying filler. If that's not the case. Then as suggested by other replies start with 36 grit on the DA then move up to 80DA. For the next stage, I would not use a Durablock or any flexible sanding tool to leveling the body fillers, you should be using a hard hand sanding 'board' that's the only way to level body fillers, in my shop. Change your sand paper often - keep it fresh so that it cuts down the highs and apply more filler in the lows, if needed. Remember that fillers and primers sand different, so you want to get the whole surface in the same substrate.

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Old 04-23-2012, 07:03 PM
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Any suggestions on how to know when I should shrink? I had some high spots. As I go more and more on this hood I am noticing more and more high spots. I think as I slap down on high spot it moves the metal and creates a high spot somewhere else; now all I'm doing is chasing high spots, which is just what ReflectImage was saying. My intuition is saying I should shrink my high spots now, rather than keep trying to slap them down. I'm not sure how they got there in the first place, or how the metal became stretched (if it is).
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Old 04-24-2012, 12:22 AM
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What's the secret/trick to skim coating panels

Before you use your Giant English Wheel Idea You need to determined why the high spots are moving all over the hood. You can spread fillers and skim coats all day long for seven days and seven nights and block and block. But you are not going to get what you want until you analysis what is going on with the metal. If you can't slap or dolly the highs down without chasing them all over - then best guess is stretched metal. It's hard to give any suggestions that could help you with your problem without seeing it first hand. If you are not sure what you are dealing with try to find someone who can help you figure out what the,.....is going on. Hoods are difficult, but as already suggested the right tool (either hand sanding board or a straight-line airboard) will help knock the highs without digging into the lows). Use a criss-cross sanding technique all the way up to the center of the hood that way you keep from creating a trough; if that's what is happening.
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Old 04-24-2012, 05:43 AM
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You must have missed it earlier but I AM using a hardboard...it's a 3M Hook-it II hardboard.
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Old 04-24-2012, 07:59 AM
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Josh, concerning the shrinking of the hood: There are two issues here. First you have to decide if shrinking is the best way. It is possible sometimes to run a slapper over an area and accomplish what you need. My favorite way is to move the slapper around the high spot while striking the slapper with another hammer. I do doubt this is going to work well on a flat hood that is going to be very springy But I would certainly try it.

If you determine you must shrink it, there is a UTUBE Visio "Dime size heat shrinking with oxy/acetylene" In this Vidio he uses a torch but the theory is the same with a stud gun shrinking tip.

I have never owned a stud gun so I can't elaborate on that.

John L
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Old 04-24-2012, 08:00 AM
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Before you have no hair left at all ,Try this:
When a high spot pops up just look under the hood....Is there a half dollar size ,rubbery cushon there that the factory uses to fasten the outter skin to the inner structure?????
Usually this is the case and whats happening is your flexing the outer skin over that spot temporarily making it high and sanding the surronding area exageates it by making everything around it low....
Sometimes just the slightest touch is all thats needed for them to raise their ugly heads....
Try hot gluing some paint sticks to the under side to stiffen it all up (the more the better) when your all done just remove the paint sticks and nobody will ever know....
As for your bondo running out before you get to the end of the hood. Heres a couple things you can do that will help speed things up..instead of mixing your filler with your spreader (slooooow) use a paint stick and stir it up till its mixed fairly well THEN use your spreader ,all it'll take is a few pats and its done ...this will shave quite a few minutes off the mixing that you can add to the spreading...
instead off pulling the filler off the pallet every time just dump it ALL on the hood ,some where you start spreading ,some in the middle and some at the end.Think of how they dump dirt when they build a road they put piles of dirt every so many feet then as they bulldoze it and start running out of dirt theres another pile before it runs out... Right? same thing....
You sound like me when I first started...I had a tough time getting it right, I was never good enough to please myself .it took a lot of help and pointers from a lot of guys .....
theres two more things I almost forgot...sometimes the rubbery glue that bonds the outter skin to the inner structure comes undone allowing the skin to move freely causing even more trouble and you'll need to re glue the two pieces before you can get any decient results( again the more the better)...
AND the beauty of sanding the bondo while its soft is you can fill only the low spots without having to skim the whole panel every time, try it you'll see what I mean right off...

Last edited by deadbodyman; 04-24-2012 at 08:11 AM.
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Old 04-24-2012, 08:26 AM
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The Old Gunslinger does make very good point about making sure there is not something underneath the skin holding it up.

Back to "Metal Shrinking" If you only need minor shrinking or are unsure of yourself, leave the wet rag off of the procedure. I rarely use the wet rag. It works for sure but you will get shrinkage with or without it, just not as much. Also it will not temper the metal as much and make it stiff.

Also keep in mind. Shrinking when overdone, or improperly done, can create all kinds of other problems. It can pull waves across the panel and cause stress that can make low spots worse if you have not correctly "evaluated" the panel.

Good luck,
John L
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Old 04-24-2012, 10:33 AM
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What''s the secret/trick to skim coating

You are right I did miss when you dropped the Durablock and started using 3M hard board . If I am understanding where you at now, you have a low area that is running the length of the high center point of hood. And you have highs that you chase all over the hood. The paint stick idea might help stabilize the flexing metal and you may not have to shrink it. For the low area along the ridge, you might try running a strip of masking tape right down the center of the ridge. Then skim that whole line to fill in that low, bridging the low with your spreader. Sand by riding the tape and the high area - sanding down with a hard board with 36 or 40 leaving it little high and then change to 80 to blend in with surrounding area. I wouldn't move up to 220 until you are happy with your leveling process.
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Old 04-25-2012, 11:14 AM
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Ok, it looks like I'll stay away from shrinking right now.

Concerning DBM's points...when I get high spots I always look under the hood to see if there is something under there pushing it up, as was the case when I had it on my stand. I keep it on a large rolling table in the shop now so it sits on a flat surface. Under the worst high spot is the substructure. My inspection thus far hasn't been much more than lift the side of the hood up a few inches to peek under and see if there's any issues so I need to look more thoroughly.

Sometimes it's also difficult for me to tell if I'm actually feeling a high spot, or if it just feels like a high spot because I just rolled my hand through a low spot. The guide coat isn't revealing much....there's a spot where the primer keeps sanding off more and more, so it's got to be a high spot.

What it really comes down to at this point is with all the uneven filler, I can't tell what's truly what anymore; there's high and low spots that are due just to filler, and there are other spots that are probably due to metal.

I'm reaching the point now where I think it may be in my best interest to strip EVERYTHING back off the hood and start from square one where I can actually use all the advice given in this thread BEFORE I have the problem; that right there will eliminate half the problems I currently have. Take my file and identify all the flaws in the metal. Work them the best I can. Fill the low spots and cut before the filler sets up...I can spot fill really well so this is where I should use my strong points. As DBM pointed out, cutting before the filler sets up makes easier/better work of it, and since I've gone back to this way it's worked out real well for me. Then I reevaluate the condition of the hood. It may be that several coats and blocking with slick sand would have taken care of it. At the time I decided I should skim I didn't know/realize the slick sand was an option.

It's really ****ty that I have to essentially waste all that filler and time, but fortunately it's Platinum and not Rage, and costs about half as much as Rage.

I actually did this with both of my fenders. I spent an entire summer trying to get them perfect and was still never happy. I had them blocked in 2k and everything. I ended up stripping off all the filler, doing a million guide coats and using my bullseye pick of all things to bump out lots of little low spots here and there. In the end I used less filler the second time around and my application was better. I've since finished blocking the high build primer and they block completely off.

You guys have half a day to stop me because when I get home I'm on a mission
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Old 04-25-2012, 08:58 PM
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Tonight I went out and did some blocking with the intent that if I sanded everything off then so be it. Instead what happened is it ended up revealing the high spots really well. I took some pics for your guys' input on how to deal with these. I could tap them down, but since I can't get access to the skin underneath I can't put a dolly there to push up on a low spot. I also stuck the scoop on so you can see where it will be in relation to all this.

The little high spot with the dime sized bare metal spot is indeed near a spot where the skin is glued to the frame, though it's not directly over it. I'm only working on the passenger's side right now.
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Old 04-25-2012, 09:19 PM
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Josh, I suspect that you can lightly tap those two spots down with a body hammer. You shouldn't have to get a dolly behind it to just bring down the high spot a little. As I mentioned earlier I have no experience with a stud puller but as defined as those two spots are, heating them up to about a dime sized red spot, tapping the area down and letting it cool will also probably do the trick. as little as it appears it needs I doubt that it even needs to be quenched. You may, however, want to take a damp rag or sponge and cool the area enough to keep the heat from damaging the surrounding primer and filler.

Thanks for the picture. It looks to me like you are on your way to success.

John L
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Old 04-25-2012, 09:40 PM
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I'll probably try tapping first. The stud welder works great for shrinking by putting a concentrated, controlled, and consistent spot of heat on a panel, but I don't have an actual shrinking tip for it, I just use it without a stud in place. The problem is it needs bare metal for the entire contact surface.

I did find this picture of the hood after it was blocked post-epoxy.
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Old 04-25-2012, 10:02 PM
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That is the thing to do. The heat is going to mess up the work you have already done. Go gently. It will not need to come down as much as you may think. Check it with your straight edge. You will be able to tell when it is down. We will be looking forward to an update.

John L
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Old 04-26-2012, 04:36 PM
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On a side note, I ran out of my z-grip bondo (about 30.00 a gal) my supply guy came by but didnt have any left on the truck. He did have the rage so I thought I'd give it a try ,that is until he told me its about 50.00 a gal...theres no way in HELLO im going to spend 50 bucks on bondo I'll stick with my tried and true Z-grip and I hate spending 30.00 for IT. 35.00 for a qt of EZ sand polly putty...RIDICULOUS.I've been using this stuff for the last 25 yrs and really dont want or feel the need to switch brands but Evercoat (brand) used to be a good deal ,now there getting like 3-M, Dupont and everyone else....
I did get my gal of SPI 2k with the hardner 90.00 THATS a deal for the best...
Whaa,whaa,whaa,britch britch, britch...I feel better though...
All I can say about all your trouble is I know EXACTLY how you feel ,Sure it was 30 yrs ago but you never forget...Now add the pressure of getting it done in a timely fashon so the shop can make money and a boss looking over your shoulder reminding you hes losing money and you can understand how being stubburnd and hard headed and thick skinned are the exact qualities everyone hates but exactly the qualities it takes to get good and why we are how we are....this kind of work isnt ez and I believe you have what it takes to get there just remember doing a hood like this is THE hardest part of doing body work and when your done you'll have really accomplished something ....
If you feel starting over is what you need to do then go right ahead and do it..you already know your a lot better now then you were when you started.I've always called it ,Paying your dues...
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Old 04-26-2012, 06:10 PM
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Quote:
Originally Posted by deadbodyman
Before you have no hair left at all ,Try this:
When a high spot pops up just look under the hood....Is there a half dollar size ,rubbery cushon there that the factory uses to fasten the outter skin to the inner structure?????
Usually this is the case and whats happening is your flexing the outer skin over that spot temporarily making it high and sanding the surronding area exageates it by making everything around it low....
Sometimes just the slightest touch is all thats needed for them to raise their ugly heads....
I've been out gently tapping these high spots, but I think you are on to something here. Underneath the high spot in the back if you're looking at the picture, there is a glob right underneath it that may be causing the high spot. What does this Old Gunslinger do when this is encountered? Should I try to cut that glob out with a knife and if so, what should I do in its place?
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