body prep advice

[Jonno]

Hi Folks,

Looking for some advice on bodywork preparation.

I'm stripping my ute back to metal prior to getting the body fixed up (this is the first time I've ever done anything like this). So far have been doing all the major panels myself using paint stripping disks on an angle grinder. Metal comes up great and, to stop it rusting, I have been using a light lanolin product (on the advice of the panel beater who will work on the rust repairs eventually).

However, I've just had some other stuff (e.g. bonnet, doors, tailgate etc) dipped and they came back looking pretty grim...very streaky and a fair amount of light surface rust (even though they were picked up immediately after the process).  I think they have just been stripped and then into a phosphate dip...but I suspect this only forms an iron phosphate, not zinc??

Question is what to do now with these bits. Should I:
a) sand them back to 'shiny' metal, and cover with lanolin (could be very difficult in some of the recesses where panels join)
b) spray with a zinc phosphate rust converter and forget about it
c) some other thing?

Guess I don't really want to get the stuff primed yet since this will obscure some of the repairs which need to be done.  Just looking for some advice on how to stablise them and what sort of condition a painter will expect them to be in before he will touch them. Also I assume dipping always results in this kind of thing because the stripped panels get wet during the process...is this so or should I never go there again??!

thanks, Jonno

[-KIWI-]

this is normal for dipped parts they are treated with pure phosporic acid after being dipped they are washed and then dipped in phosporic acid this is not zinc phosporic but is actually the same acid that dairy farmers use to cleanthere milking plants so if you know any freindly dairy farmers borrow a couple of litre of there dairy acid and it will do the same job
or try this link
http://www.tasmanchemicals.com.au/pdf/Acidet%20-%20PIS.pdf

[Emu]

Always the salesman.

[Fast_Eddie]

Jonno,

I just spent the weekend preparing panels that I had had dipped.

My panels were sprayed with the lanolin after removal from the tank, so had not started to oxidise.

However, I'm surprised yours went off so quickly. Are you sure they rinsed them properly, and/or didn't leave them lying around?

Regardless of lanolin or bare steel, you need to condition the panels using a rust convertor and a scouring pad.

After you remove all traces of grease/oil (or lanolin - easier said than done!), you follow the metal conditioning instrutions on the rust convertor bottle (as opposed to rust conversion instructions).

This usually involves diluting the rust convertor, and scouring the panels with it, really thoroughly, and then wiping down with a wet rag, follwed by a metho soaked rag, follwed by a dry rag, without letting the rust convertor dry.

After that you prepsol the panels etch prime etc within two hours of conditioning.

Hope this helps.

Regards

Edward

[Jonno]

Hi Edward,

thanks for that.  No, I'm not sure whether any of the dipping was done properly as its the first time I've had any parts done this way. All I know is that the place does a lot of business so I assumed it would be OK. Panels may have been sitting there a day max before I picked them up.

I have sanded off the surface rust and currently have them in lanolin which seems to have stopped any further reaction. Large, relatively smooth parts like the guards appear to have come out of the phosphate dip OK...they are a uniform dark grey with almost a granular texture (I assume this is the iron phosphate coat).  Its the more fiddly bits that were streaky, no uniform coat and plenty of surface rust.. Who knows what is inside some of the cavities like the tailgate...

I guess as a newcomer to this I'm still a little confused about the differences between all the basic products. For example, a phosphate dip (which I assume forms an iron phosphate coating....marketed as 'rust removal' by the dippers), and rust converter solutions which I think are normally zinc phosphate (is that so?). Is the latter more stable than the former?

Also what does an etch primer do? Some products like PPC 'Metal Ready' seem to be just another form of zinc phosphate converter.

Would any of these products leave the panels in a fit state to be left for ca. 3 months as I can't get the bodywork done until March. The guy at the bodyshop reckons he has stuff sat with lanolin on it for 6 months without any problems so maybe I should leave this on until nearer the time??

many questions (sorry)...

jonno