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Old 10-23-2019, 08:32 PM   #1
mongocanfly
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sanding delima

ive finally got around to doing the finish work on my rear fender..
if you remember, I got Dan Shady to help me turn a fender with a spare tire cutout into a reg fender...
I did some hammer and dolly work on it and got it very close ...I put a thin skim coat of filler on it and sanded it down ..followed that with finishing glaze...there were several spots that had bare metal showing and/or the filler was thin enough I could see the 1st coat of epoxy under the filler so I sprayed a coat of epoxy over the filler work
now the delima...when I was sanding, everything felt good and smooth to the touch...after I put the shiny epoxy on it you can see several flat spots..
since Ive got several different radius going on all at the same time..
what is the best way to get a good radius without leaving flat spots? ...once I sand the epoxy the shine will be gone and its extremely hard to see the flat spots...do I keep sanding and spraying epoxy (for the shine effect) or is there a simpler way to go about it..water maybe?
ive tried using just my hand with sandpaper but it doesn't help
the flat spots don't show up on the pics but they are there
after some youtubing I think Soft-Sanders may be the answer...ive got a set on order along with some guide coat powder
some pics of the area in question
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Old 10-24-2019, 09:21 PM   #2
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Re: sanding delima

Epoxy is useless as a high build. It is only intended for bare steel as corrosion resistance. It's not for spraying over any product, let alone body filler or finishing putty.

Scuff, apply two nice coats of a high quality high build urethane primer and block it out. Use a guide coat to find those low spots.

You're almost there. Nice work!
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Old 10-24-2019, 10:36 PM   #3
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Re: sanding delima

Thanks...I only used the epoxy due to all the bare metal I had showing after the filler work..not trying to use it as high build....I was going to spray with high build when i get it a little closer...maybe when the soft-sanders get here itll help me get the radius right
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Old 10-24-2019, 10:51 PM   #4
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Re: sanding delima

Are you using PSA paper? I have some 1" thick high density foam that bends, I'll throw on some paper and use this for rounded areas like you show.. Does a good job of following the contour.
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Old 10-24-2019, 11:02 PM   #5
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Re: sanding delima

Yes Robert..I'm using psa... I have been using durablocks and tried to keep a consistent arc but obviously it didnt work..they're just to stiff....I swear it looked good till I made it shiny..the soft-sanders are very flexible, but firm by what I've seen ..they showed laying the paper over the radius and then flexing the soft-sanders to fit..
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Old 10-26-2019, 12:18 PM   #6
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Re: sanding delima

Quote:
Originally Posted by Foot Stomper View Post
Epoxy is useless as a high build. It is only intended for bare steel as corrosion resistance. It's not for spraying over any product, let alone body filler or finishing putty.

Scuff, apply two nice coats of a high quality high build urethane primer and block it out. Use a guide coat to find those low spots.

You're almost there. Nice work!
I have no idea where you git all your miss info, but epoxy can be shot over body filler, finishing Putty or glaze. it can be reduced and used as a sealer. Sum like SPI have good build and can be blocked
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Old 10-26-2019, 12:30 PM   #7
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Re: sanding delima

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Originally Posted by mongocanfly View Post
Yes Robert..I'm using psa... I have been using durablocks and tried to keep a consistent arc but obviously it didnt work..they're just to stiff....I swear it looked good till I made it shiny..the soft-sanders are very flexible, but firm by what I've seen ..they showed laying the paper over the radius and then flexing the soft-sanders to fit..
Eastwood sells one that is rubber and it has a thin piece of spring steel on one side where the paper goes, it is flexible and makes a perfect radius, it also has steel rods that can be inserted to make it as stiff or as flexible as you want. They come in different lengths. Love mine
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Old 10-26-2019, 04:08 PM   #8
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Re: sanding delima

I saw those NSB29...
but I wasnt sure if it would do as tight a radius as i needed..ill get one for in the future though..thanks...
..I got one of the 14" soft sanders in the other day....it is very similar to a pool noodle and conforms to the radius very well....I sanded on the nose of the fender last night and it appears that the flat spots I was seeing was actually caused by a high spot in the filler.i used some 180g on it and it already looks better....I didn't take any pcs cause it was 2am and I had to get in the bed..but ill ad some pics tonite..
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Old 10-26-2019, 07:51 PM   #9
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Re: sanding delima

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Originally Posted by nsb29 View Post
I have no idea where you git all your miss info, but epoxy can be shot over body filler, finishing Putty or glaze. it can be reduced and used as a sealer. Sum like SPI have good build and can be blocked
Like I said before "Epoxy is useless as a high build". You are doing the group a disservice when you suggest or recommend any epoxy as a replacement for high build urethane primer. Epoxy is not designed to be sanded easily or to be applied as thick... they are two completely different products for two entirely different purposes.

I have no idea where you are getting your information, but it is not correct. Perhaps reading a TDS is a good place to start.

Cheers
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Old 10-27-2019, 12:06 AM   #10
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Re: sanding delima

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Originally Posted by nsb29 View Post
I have no idea where you git all your miss info, but epoxy can be shot over body filler, finishing Putty or glaze. it can be reduced and used as a sealer. Sum like SPI have good build and can be blocked
I agree with this.
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Old 10-27-2019, 08:10 AM   #11
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Re: sanding delima

well..
here are the pics of what I did..
I'm not gonna do any more sanding til I get the guide coat powder...local parts store don't carry it so I ordered it..i was using a light mist of paint for guide coat but I'm wanting to try the powder

I'm putting this up for people like me that have never done this before
pic 1 is the soft sander pad
pic 2 shows sandpaper layed over the radius.sticky side up
pic 3&4 shows the soft sander stuck to the sandpaper and how it holds the radius
pic 5 shows the high spot in the filler that in turn was making the flat spots I could see

with the sand paper layed over the radius.sticky side up. and the soft sander stuck to the sandpaper, it gives a firm but flexible sander the holds the radius very well...I did have to reposition the paper a couple times as the radius changes. but it seems to work very good...
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Old 10-27-2019, 11:05 AM   #12
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Re: sanding delima

Looking good Mongo. I have a step and that's exactly what I need thank you

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Old 10-27-2019, 11:22 AM   #13
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Re: sanding delima

thanks ...glad to help
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Old 10-27-2019, 12:21 PM   #14
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Re: sanding delima

One option to gloss up a part is to shoot it with some wax and grease remover. This gives a temporary shine. Works best over primer with finer grits, not so great on coarse-sanded filler or glaze.
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Old 10-28-2019, 08:20 AM   #15
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Re: sanding delima

[QUOTE=Foot Stomper;8616491]Like I said before "Epoxy is useless as a high build". You are doing the group a disservice when you suggest or recommend any epoxy as a replacement for high build urethane primer. Epoxy is not designed to be sanded easily or to be applied as thick... they are two completely different products for two entirely different purposes.

I have no idea where you are getting your information, but it is not correct. Perhaps reading a TDS is a good place to start.

Cheers[/
Thanks
Iím glad I donít have to depend on you for information. you canít sit there and read your books and have somebody else build your truck for you and think you know everything there is to know about paint and body work. I am not the first person to correct your miss information last time you were recommending bridge Epoxy. what I was correcting was your statement that it was for bare metal only and if what youíre working on is straight and does not need a high build that SPI and other epoxies have enough build that they could be blocked out.I do not use 2K high build primerís because they shrink but then thatís another subject you and your books probably donít agree with
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Old 10-28-2019, 09:21 PM   #16
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Re: sanding delima

[quote=nsb29;8617275]
Quote:
Originally Posted by Foot Stomper View Post
Like I said before "Epoxy is useless as a high build". You are doing the group a disservice when you suggest or recommend any epoxy as a replacement for high build urethane primer. Epoxy is not designed to be sanded easily or to be applied as thick... they are two completely different products for two entirely different purposes.

I have no idea where you are getting your information, but it is not correct. Perhaps reading a TDS is a good place to start.

Cheers[/
Thanks
Iím glad I donít have to depend on you for information. you canít sit there and read your books and have somebody else build your truck for you and think you know everything there is to know about paint and body work. I am not the first person to correct your miss information last time you were recommending bridge Epoxy. what I was correcting was your statement that it was for bare metal only and if what youíre working on is straight and does not need a high build that SPI and other epoxies have enough build that they could be blocked out.I do not use 2K high build primerís because they shrink but then thatís another subject you and your books probably donít agree with
Just so you know NSB, I was in the paint and body industry for 20 years. Factory trained by Sikkens, BASF and many others. I was a manufacturers rep for 5 years, technically trained painters and body men alike and had to diagnose those failures where guys played chemist by adding God knows what, pushed drying times, used spray filler as high build primer, didn't allow proper flash times between coats, used lacquer thinner instead of urethane reducer etc. etc. etc. this list goes on!

Hacks are a plenty, and will never read a TDS, always push the chemistry past it's designed features, brag about their "successes" (never their f' ups) and then blame the manufacturer when things go south.

So yes, I DO know what I'm talking about. It's clear you don't and shouldn't be suggesting backyard chemistry. Anyone who recommends an epoxy primer as a replacement for a high build urethane primer is dead wrong. Anyone who doesn't know how to properly use a urethane high build so it doesn't shrink is a rookie and shouldn't be handing out advice. Not even going to get into the whole Featherfill thing again...

NSB, it's ok to disagree, but this is the second time you've tried to label me as an idiot... the first time I let it slide and then your comments got deleted by admin... I'm not taking your crap again. You are a hack and I can't believe I wasted even two minutes on replying to you.
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Old 10-29-2019, 12:59 AM   #17
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Re: sanding delima

Quote:
Originally Posted by Foot Stomper View Post
Epoxy is useless as a high build. It is only intended for bare steel as corrosion resistance. It's not for spraying over any product, let alone body filler or finishing putty.
Why would you not spray epoxy over filler or putty? Fillers and puttys are porous, epoxies are not. More than likely after sanding filler flat there will be sand throughs of the first coats of epoxy, more epoxy has to be put down over those at a minimum before you can continue to another build primer. In doing so you get the benefit of sealing off the filler from any further moisture or contamination, and can work with a chemical bond on the next round of primer. Im sorry, but the above quote really is bad information. Ive read in multiple places by different manufactures that epoxy over filler is fine, epoxy as a sealer is fine.

Quote:
Originally Posted by Foot Stomper View Post
Anyone who recommends an epoxy primer as a replacement for a high build urethane primer is dead wrong. .
As far as I can tell no one recommend epoxy as a replacement for urethane, as an alternative yes. There are some epoxies that can be used to build and block. Depending on the situation epoxy only could be the way to go. If you have a surface that is close to flat and are willing to work with the benefits and draw backs of doing so then it will be a much more durable job in the end by leaving urethane off of it and using epoxy only.
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Old 10-29-2019, 07:32 AM   #18
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Re: sanding delima

[quote=Foot Stomper;8617676]
Quote:
Originally Posted by nsb29 View Post

Just so you know NSB, I was in the paint and body industry for 20 years. Factory trained by Sikkens, BASF and many others. I was a manufacturers rep for 5 years, technically trained painters and body men alike and had to diagnose those failures where guys played chemist by adding God knows what, pushed drying times, used spray filler as high build primer, didn't allow proper flash times between coats, used lacquer thinner instead of urethane reducer etc. etc. etc. this list goes on!

Hacks are a plenty, and will never read a TDS, always push the chemistry past it's designed features, brag about their "successes" (never their f' ups) and then blame the manufacturer when things go south.

So yes, I DO know what I'm talking about. It's clear you don't and shouldn't be suggesting backyard chemistry. Anyone who recommends an epoxy primer as a replacement for a high build urethane primer is dead wrong. Anyone who doesn't know how to properly use a urethane high build so it doesn't shrink is a rookie and shouldn't be handing out advice. Not even going to get into the whole Featherfill thing again...

NSB, it's ok to disagree, but this is the second time you've tried to label me as an idiot... the first time I let it slide and then your comments got deleted by admin... I'm not taking your crap again. You are a hack and I can't believe I wasted even two minutes on replying to you.
Every time you take an open your mouth you prove my point you’re So called credentials don’t mean squat I’ve never met a factory rep that knew what they were talking about yet Oh and by the way I was the one that deleted my posts Not the administration and told myself I wouldn’t waste my time on here anymore but here I am again getting called names My bad
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Old 10-29-2019, 07:35 AM   #19
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Re: sanding delima

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Originally Posted by sprint_9 View Post
Why would you not spray epoxy over filler or putty? Fillers and puttys are porous, epoxies are not. More than likely after sanding filler flat there will be sand throughs of the first coats of epoxy, more epoxy has to be put down over those at a minimum before you can continue to another build primer. In doing so you get the benefit of sealing off the filler from any further moisture or contamination, and can work with a chemical bond on the next round of primer. Im sorry, but the above quote really is bad information. Ive read in multiple places by different manufactures that epoxy over filler is fine, epoxy as a sealer is fine.



As far as I can tell no one recommend epoxy as a replacement for urethane, as an alternative yes. There are some epoxies that can be used to build and block. Depending on the situation epoxy only could be the way to go. If you have a surface that is close to flat and are willing to work with the benefits and draw backs of doing so then it will be a much more durable job in the end by leaving urethane off of it and using epoxy only.
Better be careful he will be calling you a hack next LMAO
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Old 10-29-2019, 08:39 AM   #20
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Re: sanding delima

Quote:
Originally Posted by mongocanfly View Post
well..
here are the pics of what I did..
I'm not gonna do any more sanding til I get the guide coat powder...local parts store don't carry it so I ordered it..i was using a light mist of paint for guide coat but I'm wanting to try the powder

I'm putting this up for people like me that have never done this before
pic 1 is the soft sander pad
pic 2 shows sandpaper layed over the radius.sticky side up
pic 3&4 shows the soft sander stuck to the sandpaper and how it holds the radius
pic 5 shows the high spot in the filler that in turn was making the flat spots I could see

with the sand paper layed over the radius.sticky side up. and the soft sander stuck to the sandpaper, it gives a firm but flexible sander the holds the radius very well...I did have to reposition the paper a couple times as the radius changes. but it seems to work very good...
Yeah the one I was referring to was a little stiff for what youíre doing I have never used those but they look like they would be ideal for what youíre using it
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Old 10-29-2019, 11:21 AM   #21
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Re: sanding delima

Yeah ..the soft sanders seem to work very well for what I'm dealing with.
I got the guide coat powder in yesterday...all I can say is wow...that stuff works great...100x better than using a mist of paint for guide coat....and if you think your filler work is looking good, this stuff will prove otherwise...I didnt take any pics of it as I had that mess and sanding dust all over my hands and dint want it on my camera, but it works wonders...it shows everthing...
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Old 10-29-2019, 11:37 AM   #22
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Re: sanding delima

Quote:
Originally Posted by mongocanfly View Post
Yeah ..the soft sanders seem to work very well for what I'm dealing with.
I got the guide coat powder in yesterday...all I can say is wow...that stuff works great...100x better than using a mist of paint for guide coat....and if you think your filler work is looking good, this stuff will prove otherwise...I didnt take any pics of it as I had that mess and sanding dust all over my hands and dint want it on my camera, but it works wonders...it shows everthing...
I have used different types of guide coat donít know what brand powdered Guid coat I used but found it kind of washed off with water sanding and went back to the spray can kind itís good you found something that works for you and Youíre right you think it looks really good then you hit it with the guide cote and start sanding to find out you werenít even close make sure you use it every time you change paper so you get the previous scratches out
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Old 10-29-2019, 07:17 PM   #23
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Re: sanding delima

I'm just dry sanding so it's working good for me...it does say it washes off easily with water....
Heres the one I'm using
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Old 11-05-2019, 03:04 PM   #24
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Re: sanding delima

Just now seeing this or I would have commented sooner. I would suggest plexiglass sanding blocks in this situation, thin enough to flex and follow the contour. A full width block would need to be less than 1/16" to be flexible enough, or a half width block could probably be made from 1/16".


One thing I don't like about foam block is that they're too soft on the surface and won't "force" the paper to cut the high spots down. The softness acts like suspension and soaks up the high spots, so you're sanding both high and low spots at the same time- working against yourself. It can work with a lot of patience and very light pressure, but it's slow and won't give the best results. Plexiglass blocks will flex enough to follow the overall shape but the surface is hard so it only contacts and cut the high spots down. Foam blocks are too soft and can follow an irregular shape, where plexiglass bends in a natural arc so your filler or primer is shaped into a consistent radius. The sandpaper also won't "bunch up" in the middle of a curve like it does with foam blocks.

I used to use durablocks and AFS adjustable sanders but have almost 100% switched over to plexiglass after seeing how much better it works. AFS sanders are better than most since they rely on a spring steel surface which helps the paper cut only the high spots, but they still don't flex as well or as naturally as plexiglass.


I recently block sanded a pair of stepside fenders that another local bodyshop had prepped. The shape is similar to the area you're blocking. The shop pretty much quit working on the project and the owner asked if we would paint the fenders so he could finish assembling the truck (the rest was already painted). I don't usually go over another shop's work but I was curious to see what they had done, they were supposed to be "ready to wetsand and paint". When they were delivered they were in polyester primer with a lot of texture so I started blocking with 80 on plexiglass blocks to knock down the texture. The other shop must have not had any type of flexible sander... the tops of the fenders were fairly straight but the ends were horribly lumpy from being improperly sanded. You can see just how lumpy they were in the pics.


First few light passes show the high/low spots.




Heavy blocking to lower the high spots. I've already cut all the way through the poly in places, yet there is still guidecoat showing in the lows that hadn't been touched yet.





More blocking to even out the shape front to rear- not focusing on the corner as much yet. Found a high spot in the metal as shown by the black epoxy. There were still low spots at this point.





Blending the corner shape into the rest of the panel, and blocking down to the body line to shape and straighten those areas. You can see that I'm all the way through the poly, a layer of high build, and into their filler work. There was still a low spot after this much blocking. If these fenders had been blocked with plexiglass from the start there would have been much less material build up and ended up much straighter.

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Old 11-05-2019, 05:49 PM   #25
mongocanfly
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Re: sanding delima

John that looks great and a great idea with the plexiglass..ill definantly try that...I think I have it very close with the foam...but everything you said about it, ive seen
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