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Old 10-07-2019, 01:32 PM   #1
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Body prep questions? Do we have a guru in the house?

Hey Everyone,

I finally got the reflective stickers off the bus. What a PAIN.

I was left with several spots where the paint came off with the sticker.

Below are pictures of the side with no prep work, Feathering out with 80 grit and primed with self etching primer.

I started out feathering the edges with my wood working orbital sander. It is very slow going.

Two questions:

Am I doing this right? Is there a better way?

Would a HF air sander work better?

Thanks.
Attached Images
File Type: jpg Paint prep on sides 001.JPG (417.1 KB, 9 views)
File Type: jpg Paint prep on sides 002.JPG (429.1 KB, 9 views)
File Type: jpg Paint prep on sides 003.JPG (304.9 KB, 10 views)
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Old 10-07-2019, 03:42 PM   #2
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I'm only a self-taught DIY advanced novice so my body work credentials are kinda weak, but here are my thoughts.


An electric random orbit sander is a fine tool to use. I did all my sanding - even the wet sanding - with mine. I tried real hard to keep water out of the top of the motor, but even so the variable speed control got a little water in it a few times and went nuts. After it dried out all was well again.


80 grit seems awful coarse for feathering paint edges - won't it make gouges that'll show through your new paint? I got as coarse as semi-worn-out 100 grit while knocking down hardened filler and glaze putty, but usually stayed with 150 or 220 for that job. 320 and even 400 for smoothing edges.


Don't forget to dewax, degrease, etc before sanding. Apparently sanding can take grease that's on the surface and smear it down into the tiny sanding scratches where it's much harder to remove.



Home Depot started carrying Diablo SandNet sanding screens in a range of grits this summer. They cost more but I used them because I figured they'd endure wet sanding better than the paper backed stuff could.


Speaking of wet sanding: if your paper is gumming up real bad, meaning little globs of paint are sticking all over the paper, then you need to be sanding wet. Those spots of paint hold the paper up off the surface like tiny bearings and prevent getting any sanding done. I figured this out while sanding epoxy primer. I don't understand why, but I found that my sanding net would gum up to where it was useless in about 30 seconds if I sanded dry. If I sanded wet I could run a single disc 10-30 minutes until the edges were tattered and torn and it still cut somewhat well.


When wet sanding fresh epoxy primer wash off the residue before it dries.. otherwise the lather epoxies itself and has to be sanded AGAIN.
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Old 10-08-2019, 05:17 AM   #3
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Family Wagon mentioned it, glazing putty. It fills in the scratches. It can be tricky to get the right amount spread into the scratches , but with time/practice one can get quite proficient. I would suggest hand sanding the glazing putty wit as fine a sand paper as your patience will allow you to get away with. I totally agree that 80 grit is WAY too rough for scratch/scrape removal. It is fairly effective for sanding contours out of (in to) Bondo as a rough-in shaping.
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Old 10-08-2019, 10:30 AM   #4
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In case you're interested in a product and technique recommendation.. here's what I used for glaze putty.
glaze.jpg


The putty is Evercoat 425 "Metal Glaze Ultra." The accessories pictured are a Clean Sheets mixing board, a 500 gram 0.01g precision digital scale, and a pile of spreaders.


The glaze putty hardens much faster than I work: when the materials are warm, say 85+ F, the work time is maybe 2 minutes. When they're cooler like 70 F you might get another minute. It's sandable in 15-20 minutes. I mixed small batches to minimize waste (and the tendency to stubbornly try to use material that's still plastic, but hardened too much to be useful).


That's where the scale came in. I'd tear off a sheet from the mixing board, lay it on the scale, and tare the scale. Squeeze out a small pile of putty - 4 to 10 grams usually, but sometimes as much as 20 grams. The hardener cream goes 2% by weight so the scale made it easy with some mental math to say "I've got 4 g of putty, so I need 0.08 g of hardener" and dispense it to roughly that weight. Then lay the mixing sheet back on the board, mix it together, and apply.
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Old 10-08-2019, 10:36 AM   #5
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Thanks for the input.

Regarding 80 grit, I thought that was awfully coarse but decided to follow direction from another site that suggested it. I have plenty of 220 on hand.
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Old 10-08-2019, 10:41 AM   #6
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Quote:
Originally Posted by PNW_Steve View Post
Thanks for the input.

Regarding 80 grit, I thought that was awfully coarse but decided to follow direction from another site that suggested it. I have plenty of 220 on hand.
80 is what you use to sand heavy body filler n stuff.
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Old 10-08-2019, 11:48 AM   #7
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Check out autoboddy101. Thereís some good stickies for beginners.

https://www.autobody101.com/forums/v...ffbffe9bade2a2

Iíve also found the Eastwood Company YouTube channel to be a good resource so far. Thereís several good videos. Check out the beginners guide painting at home video. Itís thorough.

https://m.youtube.com/channel/UCMb7dl9tHKx-zKDchXjeNfQ
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Old 10-08-2019, 11:52 AM   #8
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Quote:
Originally Posted by family wagon View Post
In case you're interested in a product and technique recommendation.. here's what I used for glaze putty.
Attachment 38325


The putty is Evercoat 425 "Metal Glaze Ultra." The accessories pictured are a Clean Sheets mixing board, a 500 gram 0.01g precision digital scale, and a pile of spreaders.


The glaze putty hardens much faster than I work: when the materials are warm, say 85+ F, the work time is maybe 2 minutes. When they're cooler like 70 F you might get another minute. It's sandable in 15-20 minutes. I mixed small batches to minimize waste (and the tendency to stubbornly try to use material that's still plastic, but hardened too much to be useful).


That's where the scale came in. I'd tear off a sheet from the mixing board, lay it on the scale, and tare the scale. Squeeze out a small pile of putty - 4 to 10 grams usually, but sometimes as much as 20 grams. The hardener cream goes 2% by weight so the scale made it easy with some mental math to say "I've got 4 g of putty, so I need 0.08 g of hardener" and dispense it to roughly that weight. Then lay the mixing sheet back on the board, mix it together, and apply.
What would be the advantages/disadvantages of this stuff as compared to Bondo? Or is it basically the same stuff?
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Old 10-08-2019, 12:12 PM   #9
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Bondo aka body filler sometimes has fiberglass strands ("kitty hair") mixed in to make it stronger, but that addition makes it harder to smooth out too. With or without fiberglass added, body filler is relatively thick or heavy because it's used for building up or filling in large depressions. I used it to help hide welds I made in sheet metal, for example where I joined smaller pieces to make a jamb and frame around my new basement storage doors.



Glaze putty in comparison is much lighter/thinner. It's almost runny - I sometimes found it slightly challenging to scrape it up from the mixing sheet onto the spreader and get it to the sheet metal without dripping. This lower viscosity is what makes glaze the right stuff to press into small pinholes, scratches, etc. I used it over the sanded body filler in many places and also in places where my new sheet metal had deep scratches from handling.



It's a sample size of one (meaning I used only one filler product and one glaze product), but I found the glaze sanded easier than the filler. Glaze costs more than filler though (2x-3x?).
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Old 10-08-2019, 06:39 PM   #10
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Thank you for your methodology, Family Wagon. I have always purchased the glazing compound in a pre-mixed tube. I like the mix as you go method you describe though and may try it once I get back into full paint prep on The Beast.
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Old 10-08-2019, 06:52 PM   #11
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Quote:
Originally Posted by family wagon View Post
Bondo aka body filler sometimes has fiberglass strands ("kitty hair") mixed in to make it stronger, but that addition makes it harder to smooth out too. With or without fiberglass added, body filler is relatively thick or heavy because it's used for building up or filling in large depressions. I used it to help hide welds I made in sheet metal, for example where I joined smaller pieces to make a jamb and frame around my new basement storage doors.



Glaze putty in comparison is much lighter/thinner. It's almost runny - I sometimes found it slightly challenging to scrape it up from the mixing sheet onto the spreader and get it to the sheet metal without dripping. This lower viscosity is what makes glaze the right stuff to press into small pinholes, scratches, etc. I used it over the sanded body filler in many places and also in places where my new sheet metal had deep scratches from handling.



It's a sample size of one (meaning I used only one filler product and one glaze product), but I found the glaze sanded easier than the filler. Glaze costs more than filler though (2x-3x?).
Bondo actually makes a putty/glaze product for filling in pinholes etc. on bondo jobs. It appears to be air-hardened since you don't have to mix anything, which makes it very convenient.
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Old 10-08-2019, 07:33 PM   #12
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Quote:
Originally Posted by musigenesis View Post
Bondo actually makes a putty/glaze product for filling in pinholes etc. on bondo jobs. It appears to be air-hardened since you don't have to mix anything, which makes it very convenient.
Yes, that is the stuff. Bondo Glazing & Spot Putty. Available at most any auto parts store and even W-Mart.
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Old 10-09-2019, 12:18 PM   #13
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One more try....

Mods, is there a problem causing my posts to disappear when I hit the post button?
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Old 10-09-2019, 01:26 PM   #14
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I think Iíd mask at the edge of the rub rail top and bottom. Adding a plastic mask below to keep things clean. Then sand all the paint between the rails. Mix a batch of bondo and apply it with a firm spreader like a wide putty knife, maybe modified to fit between the rails exactly. Work horizontally. Spread as thin as possible. Then use the widest sanding block you can make, work in an X pattern, up and down between the rails, working from one end to the other. The grit you begin with depends on how thin you can spread.
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