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Old 04-23-2004, 03:29 PM
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ospho

I have been treating my bare metal with ospho before putting my bondo on and have been having problems with the bondo lifting. Should I be rinsing the ospho off or should I leave it on? What I have been doing is letting it dry overnight and then wire brushing off the residue. Someone told me to rinse it off after about an hour and then someone else told me to do what I am doing now. Who do I need to be listening too???

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Old 04-23-2004, 04:24 PM
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You have to rinse ospho off with clear water, dry, then procede with primer and filler.
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Old 04-23-2004, 04:38 PM
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Any acid treatment should never dry. If any spot drys you are suppose to retreat that spot again/\
That is why most say to treat a 1-2 foot section at a time.
Apply and rinse.

The dried acid will do two things;
One the primer will not have good adhesion to the dried film.
Two the acid in the dry film will react and cause curing problems with the body filler.

I have not looked at one of those bottles in years but don't they have a tech sheet? Some acids are suppose to be diluted as high as 8 to 1 with water before you use? Directions on bottle?

Last edited by BarryK; 04-23-2004 at 05:06 PM.
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Old 04-24-2004, 04:31 AM
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I have never seen a tech sheet for the stuff, and the directions on the bottle are very vauge.
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Old 04-24-2004, 05:00 AM
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Quote:
Originally posted by bigjak
I have never seen a tech sheet for the stuff, and the directions on the bottle are very vauge.
===========================================

Than I would not use it.
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Old 04-24-2004, 09:06 PM
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PPg's recommendations- wire brush rusted areas,apply ospho,waited 48 hrs & DA or wire brush the residue off,apply epoxy primer(ppg's DP),wait 1 hr & apply bondo.

Ospho is phosphoric acid & is meant to dry on the metal. It kills the rust & etches metal for good adhesion.

One other thing.....do not apply bondo to bare steel. It s/b primed w/epoxy primer first.
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Old 04-24-2004, 10:20 PM
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Ok, where did you get the PPG info? Now that I have two people saying two different things, gimme some idea where ya got your info. I know the way I have been doing it, the epoxy primer sticks to it, but the bondo don't. I guess I am from the old school of putting bondo on the steel itself, without the primer. I am putting the epoxy primer over all of my bodywork after I am done, but I don't want to spend the cash on unnecessary steps. I think my Suburban has steel from hell on it. I have had more trouble with the bodywork part of this project than I have ever before. I have never used ospho before, but this truck had a lot of surface rust on it and a lot of people swear by the stuff. Maybe I'll just throw the stuff away and do it the way I used to.
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Old 04-25-2004, 09:58 AM
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Quote:
Originally posted by Don Meyer
PPg's recommendations- wire brush rusted areas,apply ospho,waited 48 hrs & DA or wire brush the residue off,apply epoxy primer(ppg's DP),wait 1 hr & apply bondo.

Ospho is phosphoric acid & is meant to dry on the metal. It kills the rust & etches metal for good adhesion.

One other thing.....do not apply bondo to bare steel. It s/b primed w/epoxy primer first.
-==========================================

Could be?, Maybe? But really?

This all could be true as things change in this business but goes
against everything I know about acids. Now the last I knew the major paint companies were leaning away from using acids because of lack of perfect environment to get the acid on and off without leaving a film in the automotive refinish part.
So I must ask was this a PPG jobber that told you this or do you have a PPG written tech sheet.
I have another class to do in WV Tuesday and this is a subject I cover and want to know all latest info out there.
A further note that I did not mention before not only will the dried film attack the body filler is creates havoc with the epoxy in a number of different ways on top of loss of adhesion. Of course 80 grit DA may get most of it off but all??
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Old 04-25-2004, 01:11 PM
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I have never washed Ospho with clear water after I have applied it. In SE Texas plastic will rust, so I cannot see much logic in using Ospho then applying water to the treated area. I have always sanded it with a DA sander, wiped it clean with Prep-Sol then epoxy primer, followed by any body filler or primer/surfacer.

Vince
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Old 04-25-2004, 01:21 PM
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I cannot see much logic in using Ospho then applying water to the treated area. I have always sanded it with a DA sander, wiped it clean with Prep-Sol then epoxy primer, followed by any body filler or primer/surfacer.

Vince [/B][/QUOTE]
--------------------------------------------------------------------------------

Vince,
Thats the problem with acid is it does require water to neutralize it.
This has been one of the problems over the years is painters hate water on bare metal.
Of course a good 80 sanding will get it off except in pit area's and that acid could play a role in longterm problems if any left behind.
I just see no point in using it at all. If its rust and you can't blast it or dip it don't paint it!
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Old 04-25-2004, 06:07 PM
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Things have changed in the painting/chemical field!!! The items I pointed out are NOT NEW. I learned these at ppg paint school about 10 -15 yrs ago.
Here is a web site www.autobodystore.com ask your questions here! Todays chemicals are so expensive that you better do it rite the first time........Dr Don
You can also get PPg product info on line. Do a search for PPG
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Old 04-25-2004, 06:47 PM
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I just don't understand.

QUOTE
org. posted by Barryk

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I just see no point in using it at all. If its rust and you can't blast it or dip it don't paint it!
__________________________________________________



If the system of applying filler directly to clean bare metal has worked for all these years, why in the world would anyone want to add two more products and steps prepping metal to paint????

The acid stuff has been around for 40 or 50 years, I tried it then and did not get good results. I'm sure there are certain circumstances when the acid should be used. In my three shops
we havn't used a quart in 20 years. I have put out thousands of repaired panels with filler on them, and never had a one come back with any problem of any kind.

Like I've said many times, why fix something if it isn't broken?

Troy

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Old 04-25-2004, 07:09 PM
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I think you misread my post! I'm not for using the acid! It is not a good cure for rust thats why I said " blast or dip it or don't paint it!"
It is just another step that has a big potential of causing unnecessary problems both short term and long term!


"As far as your statement why not just put filler over bare metal"
Because its a major improvement putting filler over epoxy for durability and long term life.
Everyday production work for cars the owner most likely not even own in two to three years, why waist the time and money?

Most of the people here are trying to learn and should be at least advised the best options out there. Lacquer worked great also in its heyday.

Last edited by BarryK; 04-25-2004 at 07:25 PM.
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Old 04-25-2004, 07:50 PM
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Posted by Barryk;

__________________________________________________
I think you misread my post! I'm not for using the acid! It is not a good cure for rust thats why I said " blast or dip it or don't paint it!"
It is just another step that has a big potential of causing unnecessary problems both short term and long term!
__________________________________________________


You misread my post. I agreed with you on the use of acid of any kind.

I have cars setting here that did not have any epoxy used on them. They were done in the early 70s and still look good.

To learn, they need exposed to all successful methods, I do not tell people that post here that they are wrong, and that I am right or know more than they do. I just give my opinion from many years of successful shop operation.

Troy

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Old 04-25-2004, 10:25 PM
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The only reason I was using the ospho on this truck is because of the abundance of surface rust, and I have read that many people on other boards swear by the stuff. It seems that everyone has a different way of using it. I did find their website and they say you are to leave it on til it dries then paint over it. I was thinking about having someone else shoot the truck because it is too tall to get in my garage, so I talked to two very reputable shops in the area. They both said that they would not guarantee how long it would last if the metal was sandblasted, something about the pores in the metal can never properly be sealed after sandblasting. They both said that the ospho type product was the way to go, but they were differing on how to use it. The epoxy primer sticks to the stuff like nobodys business, but the filler don't seem like it wants to at times. Maybe I'll just blast it>
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