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MG MGB Technical - epoxy/etch primers

I have some panel work to do on my MGB repaint which I will need to use some filler on. I have used etch primer on previous panels and it reacts with the filler and subsequently shows through the gloss coat. I'm contemplating using an epoxy primer but have just spoken to Lechler who advise that although their epoxy primer does not contain isocyanates it still requires an air fed mask. I'm using the relevant face mask when spraying but it's not a full air fed system. So how do I proceed. I need to use filler, I need to have a good primer adhesion to the metal and I want to still be alive at the end of it! I've got some Metal Prep for panel derusting. Do I put normal primer on top of this. Will it give the same protection as etch/epoxy. In a bit of a quandry and I'm running out of weather (again).
Steve Church

Steve,
Have just completed a restoration and used etch prime aerosol, had no problem whatsoever with reaction to filler. What the body people, where I was doing the work, did say though was NOT to treat the etch as a primer!! But use a very light coat to get the adhesion, and then prime as normal. If you are using a proper "active" mask, in a well ventilated area, I would have thought there was little chance of death!!** But remember the active filters have a shelf life and need replacing often.
Allan Reeling

It sounds as if you have 'filled' the bare metal and want to put the etch primer on top ??? Shouldn't it be the other way round ?

If the rusty bits are on "show" you need to clean them so they are bright but if they are underneath the choice is between the coating they put on ships' bottoms or Zinga. Cold galvanising is infinitely superior if expensive.
R
Roger W

Roger,
I thought that filler should be put onto bare metal......mind you so should etch primer. I'll try it etch first then filler. The trouble comes when you sand through the primer when cutting back and need to put more on and then it overlaps the filler. Looks like I'll have to do with normal primer in those instances.
Steve Church

Steve,
etch, prime, fill and prime again.
I think I've mentioned this before; epoxy on bare, properly prepared, metal. Use an active filter mask and there's no requirement for an air fed mask.

best of...
MGmike

M McAndrew

Active carbon filters will absorb all organic vapours, including isocyanates, IMHO.
Art Pearse

Hi Everyone,

Like Steve, I'm doing quite a bit of fresh metal replacement which includes new floor pans, middle and outer sills, and rear valance repairs. I'm soon to start welding and would like to be in a position to carry out the metal paint work straight afterwards.

I would greatly appreciate your replies on my burning queries below.

(1) I've studied the procedure for preparation and have been considering the etch/epoxy primer/urethane top coat combination; can anyone advise on this approach?


(2) Can anyone enlighten me on the choice between single-pack and two-pack etch primer?


(3) Some of the metal around the sills needs a little rust treatment before applying any paint. I've used before Jenolite treatment, which contains phosphoric acid; PH Down phosphoric acid is another alternative. Does anyone have any experience with effective rust treatments?


(4) In the absence of access to sophisticated paint shop equipment, is it advisable to use brush-on etch primer and epoxy primer in the areas indicated above?


(5) Does the factory black covering need to be removed before starting the protective paint layering?

If so, what is recommended to remove this black paint?


(6) Should the bare metal be abraded well before applying the etch primer? If so, what grade of paper is recommended?

Thanks for your patience in responding,
Brian
Brian McIlvenna

Hi Everyone,

Like Steve, I'm doing quite a bit of fresh metal replacement which includes new floor pans, middle and outer sills, and rear valance repairs. I'm soon to start welding and would like to be in a position to carry out the metal paint work straight afterwards.

I would greatly appreciate your replies on my burning queries below.

(1) I've studied the procedure for preparation and have been considering the etch/epoxy primer/urethane top coat; can anyone advise on this combination?

(2) Can anyone enlighten me on the choice between single-pack and two-pack etch primer?

(3) Some of the metal around the sills needs a little rust treatment before applying any paint. I've used before Jenolite treatment, which contains phosphoric acid; PH Down phosphoric acid is another alternative. Does anyone have any experience with effective rust treatments?

(4) In the absence of access to sophisticated paint shop equipment, is it advisable to use brush-on etch primer and epoxy primer in the areas indicated above?

(5) Does the factory black covering need to be removed before starting the protective paint layering? If so, what is recommended to remove this black paint?

(6) Should the bare metal be abraded well before applying the etch primer? If so, what grade of paper is recommended?

Thanks for your patience in responding,
Brian
Brian McIlvenna

Art isocyanates are nothing to be messed with. I have supplied air and a hood but they are a hassel when all you want to do is paint a small part. I have never been able to find a mask that says it stops it. Keep in mind if you can smell the paint your breathing the isocyanates and as I understand can be absorbed thru the skin and eyes.
gary starr

Hi All,

I've been investigating further the use of etch primer in car bodies. I've been told by an auto supplier that etch primer is only used on metals where primer adhesion would be otherwise problematic, such as aluminium or stainless steel.

So, do we need etch primer on the body areas that are hidden from view (floor pans, inner and middle sill areas in my case)?

In the absence of an etch primer, would an epoxy undercoat provide any rust protection or would a different undercoat type be needed?

Thanks,
Brian

Brian McIlvenna

Filler should only ever be applied to bare metal. If you paint first & then apply filler you will always see the edges through the final coat of paint. So pepare the base metal, fill, sand, etch, prime, finish coat.
G Britnell

Well thats as clear as mud then . . .
P Land

It appears that you will get as many differing answers as people you ask....

I've chosen these guys;
http://www.rust.co.uk/system-selection-start-here/c32739/#
in the hopes that rust will been held at bay for slightly longer than usual....

They advocate filler on top of the first epoxy primer coat.

Best of....
MGmike

M McAndrew

This thread was discussed between 07/10/2014 and 02/11/2014

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