|Today 06:40 AM|
The factory uses electrostatic primer.
|Today 06:37 AM|
It sounds like you are giving advice for a collision shop job that only needs to last a couple of years, and if Barry printed your advice on the tech sheet, he would sell a lot more shops on his epoxy.
For maximum adhesion, reduced epoxy shouldn't be used on bare metal, and 80 grit DA scratches are easily covered with SPI epoxy.
I think you know better than what you are posting here, so I don't want to waste any more time on this.
|Today 06:36 AM|
It has bothered me from the near the very start of this thread that you push yourself as an expert with procedures that are so far off from what is accepted practice. This thread should have been closed long ago.
Not that I care what you do and what you push. It's the unsuspecting novice hobbyist that reads your stuff that I'm concerned about.
|Today 05:57 AM|
Also remember media blasting is NOT a good idea if the car is not completely takin apart...and not every car is a long term resto ,some are only in the shop a couple days.
|Today 05:41 AM|
I wouldn't loose to much sleep with those freckles ...
usually two applications of Ospho ,scrubbed in with a red scotch brite does pretty good then when you sand it all that's left is basicly a stain that can be primed,trying to chase all those freckles down is a losing battle ,I've never had them come back or cause any problems in the paint later on...
|Today 05:20 AM|
|Yesterday 09:45 AM|
The instructions for SPI epoxy are clear.
Sand metal with a D/A and 80 grit.
Where I can't get to with a D/A, I think the finish that a media blast leaves is good too. I use Black Diamond media.
|Yesterday 08:11 AM|
|Chevymon||Mike, you have given a lot of good information here, but I just don't agree with what you are saying, and I use SPI also. BTW, Its hard for us--at home--to match what the factory was doing with primer 60 years ago.|
|Yesterday 06:46 AM|
|Yesterday 06:24 AM|
|deadbodyman||When the factory sprays epoxy the metal is NOT sanded...I don't know about other epoxies ,I only use SPI ,its been so long now I don't remember using anything else since DP-40... IMO most epoxies are about useless PPG hasn't had a good epoxy primer since DP-40 even then,as good as it was, it sanded like a rock,the only way to sand it was with 80 grit...It's also a good idea to check your adheasion before starting your filler work .I do this with a razor scraper and try scraping the epoxy off the metal but in most cases the average guy can test adheasion by sanding the epoxy down to the metal with 180 and feathering the epoxy back to make sure it feathers back nicely with no broken edges....|
|04-25-2015 07:28 PM|
pugsy is totally right on that. I use a hand held brush, like a tooth brush but it needs to be stainless steel. It doesn't throw the acid all over the place, and you don't have to reapply as often. Just like he said, you have to keep after it until its just shiny white metal when reapplying. If you get a sludge, that has to all come off while the sludge is dissolved.
Mike, I'm sure you know, but for those that don't---- as far as I know all the epoxy manufacturers require an 80 grit DA scratch on bare metal, although PPG is OK with 180 scratch when using their metal prep with zinc phosphate in it.
Tamco paint makes an epoxy---similar to what boeing uses---that can go over anything, even if its unsanded, but they still recommend sanding when ever possible. And they claim to be the only one available to the public with that option. I have used it and it works.
|04-25-2015 05:06 PM|
I've used a rust convertor which is basically the same as Ospho. The instructions state that the black converted rust is ready for primer and paint but it's a bunch of bull.
I ended up using a small spot blaster to get into the pits.
A wire wheel in a grinder or drill may sometimes get it all out.
Apply more acid and if it turns black, you're not finished yet.
Eventually, the acid won't turn anything black anymore and you've got all the rust out.
|04-25-2015 11:28 AM|
DeadBodyman, My concern now if how I can get rid of the minor black freckles left on the paint. I was hoping that these spots, which were there before the ospho treatment, were already there. Theyre a PITA to take off and was hoping I didnt have to grind them off the entire car?
Any opinion on this? Im I over thinking this?
|04-24-2015 02:58 PM|
|deadbodyman||yes, sometimes I do ,sometimes just 80. I tend to work through the grits when prepping bare metal. once it starts shining and getting super clean I have a hard time stopping But I use epoxy for everything, over my filler work and as a sealer when I need one.its a self etching primer too, so it sticks great to unsanded metal as well .theres really no need for any other primers ,SPI epoxy is all I use 95% of the time|
|04-24-2015 11:03 AM|
|This thread has more than 15 replies. Click here to review the whole thread.|