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The Ospho Solution..(rust removal)

353K views 664 replies 61 participants last post by  Lizer 
#1 ·
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...
...
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.
 

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#78 ·
Shine..thanks for the correction on my lingo. The manufacturer suggests using both of the products in order to achieve both heat decrease and sound deadening results...spray one then the other...lots of money for the product, but it would save a ton of time vs cutting and sticking Dynamat and heat barrier insulation w/foil tapeing...the old money vs time

Still leaning to treating my rusty areas with the Ospho. One thought I had was if its important to get it down into the rusty seams and panel folds such as where door skins fold over...then how the hell do you reach down in there and rough up the scale so that a primer will stick?....I can see how easy it is on an outer panel...but not in hard to reach places...thanks Chopper
 
#79 ·
i have used lizardskin for many years. imo it is a better product because it leaves no voids for heat to get in. the main thing with insulation is heat migration . meaning some products will eventually be as hot on the top as on the bottom . i blast a car, wash it, epoxy it then soak it in lizardskin. under the dash , in door pillars , everywhere. it seals up the cabin well. under the car i use spi bed liner . it is a urethane base. i don't like any of the petroleum based coatings. ok for the bed of the farm truck but not on my hotrod.
as for acid the warnings have been given by the paint mfrs and many of the professional painters . it is up to the individual to research the claims and decide for themselves.
 
#82 ·
Preciate it

deadbodyman said:
Just be careful and follow the proceedure ,theres no reason your work wont come out the same way..........I guess I better get started on those fenders.. :sweat: :sweat:
I guess I can't read very well. I evidently left too much Ospho on the panels and it's some thick stuff after it dries. I'm working it off with more Ospho and red scuff pads.
 
#83 ·
Thats OK, reapplying it works well for that,a second coat ,third coat,as many as you want or need just wipe it off as best you can with those shop towels...If you have an old (or el cheapo) DA with a velcro pad you can stick the red scuff pads on it to make working big areas much easier..After wire wheeling the rust that is..After it dries completely there can be blacker brushlike textures where it was left a little thick,this is normal and sands right off with 180 the blackish marks (stains) will mostly stay but it'll smooth right out for you...At this point it done its work cleaning and protecting the bare metal and you can sand it ALL right off if you want or just a quick breeze over..I use 180 grit on my DA followed by W&G and epoxy primer...
In all the years I've used Ospho I've never used water to neutralize it, it dosent need it any more than an etching primer would need to be neutraized before applying other primers.......Like etching primer it HAS phosphoric acid in it but its NOT straight Phos acid...
 
#84 ·
Life is hard, harder when you're stupid

I'm doing my engine bay and frame rails. In my haste, and not reading every sentence, I have Ospho in a bunch of hard to reach areas and tiny crevices. Will my primer and paint adhere to this without neutralizing it first? How about wire brushing it out of all the crevices? :pain:
 
#85 ·
Body fillers and Ospho residue

Even tho I know it's here somewhere : I found out the hard way that fillers won't set up if applied over Ospho treated panel. I have read that "back in the day" all etching primer needed to be removed where fillers were to be applied ... guess I should have put 2 and 2 together but ...... Anyway , I need to be certain any dents/dings areas, etc are completely free of any acid traces, obviously. I don't have any issue shooting Omni epoxy over Ospho treated and prepped areas, but areas needing ANY filler or Icing, etc CANNOT have traces of acid - what is the best way going forward I should tackle this (besides "quit using the Ospho"). This is my third Mopar resto - I'm just a weekend warrior and Ospho allows me the time I need to work with the bare metals here in soggy, wet Florida !
 
#86 ·
dixiedart said:
Even tho I know it's here somewhere : I found out the hard way that fillers won't set up if applied over Ospho treated panel. I have read that "back in the day" all etching primer needed to be removed where fillers were to be applied ... guess I should have put 2 and 2 together but ...... Anyway , I need to be certain any dents/dings areas, etc are completely free of any acid traces, obviously. I don't have any issue shooting Omni epoxy over Ospho treated and prepped areas, but areas needing ANY filler or Icing, etc CANNOT have traces of acid - what is the best way going forward I should tackle this (besides "quit using the Ospho"). This is my third Mopar resto - I'm just a weekend warrior and Ospho allows me the time I need to work with the bare metals here in soggy, wet Florida !
It's not just filler. Polyester primers like FeatherFill and Slick Sand won't stick either.
 
#87 ·
70 ElCam said:
I'm doing my engine bay and frame rails. In my haste, and not reading every sentence, I have Ospho in a bunch of hard to reach areas and tiny crevices. Will my primer and paint adhere to this without neutralizing it first? How about wire brushing it out of all the crevices? :pain:
.......................YOU DONT NEED TO NEUTRALIZE OSPHO...........................
Just let the ospho dry for a day or two ,sand or scuff ,prep with W&G then prime....
However ,if it gets on painted surfaces (like your firewall) it wont dry so well and will need to be washed off with soapy water.so in this instance You should spray it down with soapy water and rinse it off then start your scuffing and prep work.
 
#88 ·
dixiedart said:
Even tho I know it's here somewhere : I found out the hard way that fillers won't set up if applied over Ospho treated panel. I have read that "back in the day" all etching primer needed to be removed where fillers were to be applied ... guess I should have put 2 and 2 together but ...... Anyway , I need to be certain any dents/dings areas, etc are completely free of any acid traces, obviously. I don't have any issue shooting Omni epoxy over Ospho treated and prepped areas, but areas needing ANY filler or Icing, etc CANNOT have traces of acid - what is the best way going forward I should tackle this (besides "quit using the Ospho"). This is my third Mopar resto - I'm just a weekend warrior and Ospho allows me the time I need to work with the bare metals here in soggy, wet Florida !
Your absolutly right fillers wont stick to acid primers or Ospho treated metal I also learned that the hard way. Epoxy does stick very well to it,so you would epoxy first then apply the filler to the epoxy.I always sand the epoxy first with 180,apply the filler and reapply the epoxy making a sort of sandwitch..
I've never used poly primers over ospho so I dont know about that but ,if I was in need of a poly super build primer I would use it over the sanded epoxy.I've used nason and Omini epoxy but they arnt very good,SPI costs about the same and as far as Im concerned its the best dang epoxy primer out there at any price....I'll post some pics of the "epoxy first" process.
 
#89 ·
A lot of these old pics arnt to good but it'll give you a basic idea of how things should look as you go............I'm not doing the whole car just the roof for now...
First I chem stripped the old paint off the roof then rinced the residue with lacquer thinner and sanded with 80 da ....
Before I start with the Ospho I cleaned with wax& grease remover ...
Sorry, I dont have any pics of how I wire wheeled and treated the heavy rust
 

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#92 ·
I did a quick blocking to get a good idea where the worse spots were then hammered and straightened and applied polly putty because its thinner and will fill the pitts better than bondo.
Notice the spot I sanded to the metal in the last pic.
 

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#95 ·
Top it off with more epoxy and its ready for sand and paint or if needed a 2k primer.One of the things I like about this SPI epoxy is you can also build it ,it just takes longer to cure than 2k's but it also a lot more chip resistant...The extra cure time is worth the wait for some jobs..
 

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#97 ·
Thanks - I was such a "freak" regarding treating bare metal that if I ever had small areas of sand through when doing bodywork, I'd wipe a little ospho on until I could get back on the job (sometimes not until following weekend) ... these would be the problem areas, I've learned my lesson. I'll use ospho once or twice for maintaining bare panels until I am ready to prime. I typically like to plan on shooting multiple panels at the same time as I have to plan my days around weather, neighbors, etc so the ospho helps me "maintain" some integrity until I can shoot. If the product is used correctly, it is a life saver for guys like me that take a loooong time to complete their project. I would like to use the SPI but I want to know for a fact how to correctly prep the ospho'ed metal before application. I use the PPG product because I know there are no issues with the ospho as it's basically the same as their green DX520 (phosphoric acid), and they instruct to scuff residue and shoot their epoxy primers over the prepped surface , gives me some peace of mind knowing there shouldn't be any compatibility issues here .......... I'd try SPI but they don't seem to condone and definitely don't recommend, acid preps .... while PPG does (DX520 and DP primers).
 
#100 ·
i would suggest you call barry knives at spi before doing anything. or use another product and before using ppg i suggest you refer to the advanced refinish systems tech book. it clearly states to rinse after any of their metal preps. it also warns against applying etch too wet because of poor adhesion.
 
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