This is the start of a thread dedicated to successful rust removal using ospho,a water based phosphric acid product I've been using professionally for many years.
Ospho has some advantages over other methods, mainly a DIY can do it at home inexpensively with little mess,fairly easily.
I'll try to answer any questions and offer some advice on the successful use of this product.
.....First,I'll start with the most common use : To remove surface rust That has accumulated on unprotected steel....Then heavly rusted and pitted metal,and using it to prevent surface rust of freshly stripped steel...
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The pics below show the trunk floor and wheel wells I made for my old car.After making the pieces and screwing them together ,it got cold out and I put the car up for a couple months and the steel got pretty rusty.
In the interest of time I'll just do a spot to show how its done and what Materials you'll need.Bare with me I'm a newbie with the computer.
I have never used Ospho and do not have any basis to judge it. But.....DeadBodyMan (Mike) has always advised to wipe of all excess after treating BEFORE it dries. Then retreating and washing panel before painting to remove the acid. He also advises sanding the area with a DA with 80 grit for a good tooth. As Shine says, Once the panel is retreated to eliminate any acid residue and then washed with water the acid is no longer an issue.
It concerns me when I hear people say somebody's idea does not work when they have not done it his way.
Bottom line is, any acid residue left on a panel will have a negative effect on adhesion.
One more thought. Maybe the thing that is misleading folks is Mike saying to treat the panel and it will not rust back. That is because of the residue that protects the panel. Never has anyone said it is advisable to just pick the panel up and paint it without properly preparing it.
As a matter of fact ,John I've warned against doing this over and over and its still the #1 mistake people make...I also warned over and over to check adheasion of the epoxy BEFORE going any further...
any idiot can remove rust and get clean metal with the stuff or use it to keep the metal from rusting, its AFTER that where the problems start...and its also THE reason for this thread...To use ospho sucessfully...as I do and many ,many others do....
Well ok, Its really All the fame and fortune,helping others has nothing to do with it...
I for one am also grateful this thread IS STILL ACTIVE! JEEZ, why close and archive away such a plethora of knowledge??? I went to google searching for rust solutions on my 65 chev, and found this site. Its been great and very informative reading this entire thread over the last week in between the hours I spend out back working in the shade on my project. I feel a lot more comfortable now using a little ospho in those inconspicuous and hard to reach areas, mostly inside of the quarters and interior roof panel, oh and also the under side of the trunk deck and package tray. Car was rot free until the previous owner had a leak in his garage and it dripped on the rear window for years without repair...:welcome:
All I've ever used has been Ospho.I've never rinsed it off or touched it with water I just let it dry.the heavier spots where you see the streaks stay tacky longer than the rest and if you were to prime over them while tacky, I'm sure there would be problems.
When I'm ready to prime, I just sand with a da or scuff pad and wipe off with wax & grease remover.I'm pretty sure I'll be priming tomorrow so you'll see the whole process.
you left acid residue on the panel to dry . this is exactly what the paint mfg tell you not to do. clean and etch with it but rinse it off while wet if your about to paint. if your storing for long term metal work leave it. but reapply and rinse before paint .
How do you rince it Shine? with just a damp rag or lots of water? I always sand the coating off but this sounds like it may be a good way too...
I have another question .....I stripped my camaro fenders to the metal and since there wasnt any rust at all and I was rushing, I was going skip matal prep with ospho but its been very hot and I kept getting sweat dripping on the metal and my sweaty tee shirt always rubbing on it when I'm not paying attention, leaving rust spots after a few hours do you think I could sand the rust spots out and prime it or will the rust come back if I dont do something after sanding...You must have the same trouble keeping sweat off the bare metal I always wear gloves but my sweaty forearm hits it or my soaking wet shirt...what do you do ? other than getting A/C in the shop...I know your against using acid and I thought of you when I was doing this without the acid and thought I'd ask....
I began using Deadbodyman's technique for Ospho rust treatment on a surfaced rusted car that I will be working on in about 2-3 months. Just wanted to slow down the rust as much as possible. As I sprayed Ospho and cleaned up the surface rust I noticed some dark black spots on the metal. Do these need to come off before I Epoxy over the ,metal? Or does the fact that they are black mean that the rust has neutrealized? FYI; these blackish spots where there before I used the Ospho process
Lizer, I should of clarified a bit more. I noticed the spots there before but they were not black like they appeared after the Ospho treatment. They were somewhat of a darker rust color before
I use one of these small wire wheels in a reversable drill.
There are larger wire wheels, but I think they do not get into the bottom of rust pits as well. After using the wire wheel, for a while, the bristles lean over, away from the directionn of rotation, and reversing the direction of rotation, the bristles dig in a little better. Slow speeds seem to work work better for me, also.
I'll try...converting rust is never a good idea no matter what the product claims....
Theres many ways to "remove" rust,Ospho is one of them without the mess of media blasting.
Ospho has some advantages over other methods like removing rust on a running and driving car because you don't have to worry about the glass and sand getting into the motor and other moving parts ,causing problems down the road.
If you use Ospho be sure to remove the protective coating that keeps the metal from rusting....
theres two ways to remove the coating when your ready to prime. 1) thuroly sand it off or 2) rewet with more ospho and rince off while its wet. I prefer sanding it off ,starting with 80 then 180 and finally 320 all dry sanded with a DA.. and a wire wheel on the pitted rust ,slowly with a coarse wheel as not to polish the surface.
So far SPI epoxy primer works best so its a great combo...
when done properly there are no adheasion problems BUT it does have to be done properly if not you WILL have problems so "yes" use it but use it properly. I've had great success with it for many years with no problems at all.....
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
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?
The black freckles are converted rust. That is if you used acid on it. Under the black will be nice brown rust ready to cause paint failure.
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.
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.
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....
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.
also true,thats what the instructions on the can says....the instructions also "used" to say DONT use acid products on the metal (the main reason I started this thread) Think about it......lets say I have a brand new after market hood with that crappy black primer on it,its so thin it sands right off with 320.should I sand it of with 80 and scratch the heck out of it and put 80 scratches in it that will just have to be filled AND sanded again? NO,absolutely NOT ,I sand that primer off with 320 and spray my SPI epoxy reduced like a sealer then go right to paint.why make all that extra work when you don't need too. remember your filler lessons "if theres no sand scratches to begin with" theres no scratches that'll comeback in the paint.NEVER rely on the primer to do your filling for you.....
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.
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.
I don't even know how many times I've said that 2 coats of epoxy will cover 80 scratches 20-30 on this thread alone? I got the reduced epoxy as a sealer over bare metal and right to paint directly from Barry K himself except he said it could be reduced up to 40% I've done it ,it works, no waiting ,the epoxy is ready to paint in 30 minutes to an hour after spraying over bare metal and your right it is NOT something you want to do on your resto but like I said not every car IS a resto and doing a collision job at the resto quality would be the wrong way just as doing restos in the production way would be the wrong way , you'd be out of business in months if you did. different cars HAVE to be done different ways it all depends on the car, for instance some need to be stripped to the metal and some don't some need to be primed from bumper to bumper and blocked lazer straight ,some don't they only need primer in a few spots.
Im a novice and dont take any one's comments as the 'how to' process alone. I like gathering advice and trying out those methods and only myself can determine what worked best and/or drawing my own conclusion.
I hope all other novice's out there are doing the same.
Deadbodyman has provided some great help for me with his recommendations in the past.
Ive been stripping metal with 80grit paper then 2-3 coats of SPI Epoxy, followed by a contrasting color Polyester primer for build. I work the small imperfections and blocking with the Polyester. Once I start seeing the contrasting color Epoxy in the bottom I stop, shoot more Poly, over and over until Im satisfied. Ive been surprised myself how straight my projects have came out using this method.
the method of application electro static,dipped ,sprayed or even brushed on doesn't matter the epoxy is on the cars.I made the mistake of saying sprayed and a few got hung up on the one word what I should have wrote would be the factory APPLIED epoxy because theres no special primer for dipping cars, its not called dipping primer. therefor calling a primer electrostatic primer would be just as ridiculus since its just a method of application done by creating an electrical charge on the object being painted and opposite charge in the paint or primer since like charges oppose and opposite charges attract very much like the n pole of a magnet attracts the south pole and north to north repel...run down to the paint store and ask for electro static primer ,once they stop laughing tell us what the first two questions they asked. then tell them you want to dip some parts in primer so you would like sme dipping primer with it. that should pretty much make their day...
OR, here's a fabulous idea. Just asking the freaking company.
Barry says epoxy will stick to perfectly clean unsanded metal with 100% adhesion.
You guys are like a bunch of little girls fighting.
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