Cleared out rust: prime first or fill first?
Discussion
I'm trying to deal with the tradional bucket loads of rust on my MR2 (provided I haven't sh@gged the engine and turned it into spare parts 
).
So here's the question:
If I clear out the rust with rust clearing product or brute force, would it be better in the long run to 1: First fill the cavities left / put on the fibreglass reshaping that'll be needed, and then spray with anti rust primer, or
2: Prime the bare metal first, then put bodyfiller/fibreglass?
I'd've said 2 for rust protection, but how well will the fibreglass/filler bond to the primer?
). So here's the question:
If I clear out the rust with rust clearing product or brute force, would it be better in the long run to 1: First fill the cavities left / put on the fibreglass reshaping that'll be needed, and then spray with anti rust primer, or
2: Prime the bare metal first, then put bodyfiller/fibreglass?
I'd've said 2 for rust protection, but how well will the fibreglass/filler bond to the primer?
Down to shiny metal 
not just cleared loose rust ?
Any holes in the metal ? If there are fill them with more metal, then fill, prime, paint in that order
The materials depend on how good a job you want to do
can you show us a photo ?
PS Yertis, Why would you need rust killing primer on a rust free area
:tonguefirmlyincheek:
Forgot to say, where abouts on the car is the problem
>> Edited by incorrigible on Friday 7th February 15:57
not just cleared loose rust ? Any holes in the metal ? If there are fill them with more metal, then fill, prime, paint in that order
The materials depend on how good a job you want to do
can you show us a photo ?
PS Yertis, Why would you need rust killing primer on a rust free area
:tonguefirmlyincheek: Forgot to say, where abouts on the car is the problem
>> Edited by incorrigible on Friday 7th February 15:57
You need to remove every scrap of rust. If you don't prepare it properly it will only be a short time before you're back to square one. Mechanical to bare metal, then chemical afterwards. If you're going to use fibre glass, I suggest you have a play with the stuff first. It has many lores to itself, and can be very difficult to finish once its cured. Another good rule of thumb is that you can't have enough primer, if in doubt prime it...good luck
It's the wheel arches mainly - all of them, but the o/s/r is dire, I've thought about just cutting it out and getting a new one welded in but the car's just not worth the expense. I plan to use a kit which is pre-made fibreglass rear arches and other bits. I'll try and put up some pics, but I tell you it's not a pretty sight!
Last time I did much like this, 11 years ago to a Montego (better car than it got credit for, till I wrecked it), I filled onto bare metal then primed - and of course as you all say the rust came back inside a couple of months.
Last time I did much like this, 11 years ago to a Montego (better car than it got credit for, till I wrecked it
), I filled onto bare metal then primed - and of course as you all say the rust came back inside a couple of months.1) Get right down to nice shiny steel using rotary wire brush or abrasive disc with electric drill - on BOTH sides of panel if possible.
2) Cut any crappy perforated brown stuff that you can't get down to nice shiny steel out.
3a) If non-structural to be repaired with fibreglass then use Jenolite to treat surface for any non-obvious rust (both sides of panel). Then bash area round hole with hammer so all edges below panel level. Then use knife/srewdriver to score the surface to provide good key for fibreglass. Then apply fibreglass, again to both sides of panel if possible. Then filler, prime and paint. And don't forget to do the underside.
3b)If structural you'll need to weld new steel in, but again treat area round hole with Jenolite, then weld in steel patch, hammer/grind/fill until flush then prime and paint.
4) Consider buying car that doesn't rust!
2) Cut any crappy perforated brown stuff that you can't get down to nice shiny steel out.
3a) If non-structural to be repaired with fibreglass then use Jenolite to treat surface for any non-obvious rust (both sides of panel). Then bash area round hole with hammer so all edges below panel level. Then use knife/srewdriver to score the surface to provide good key for fibreglass. Then apply fibreglass, again to both sides of panel if possible. Then filler, prime and paint. And don't forget to do the underside.
3b)If structural you'll need to weld new steel in, but again treat area round hole with Jenolite, then weld in steel patch, hammer/grind/fill until flush then prime and paint.
4) Consider buying car that doesn't rust!
It was a Triumph GT6 
and was genetically coded to rust. A couple of clarifications to grahambells list
Only put filler onto bare metal, not scored paint, you shouldn't need to score the metal before adding glass/filler
in this case, wire brushing is going to be useless because the arch will be perforated or at best too thin for a decent repair (educated guess)
How much time/money have you got, for about £1 you could do a good repair if you had loads of time and a welder (probably about £20 after filler and primer)
Are arch panels really that prohibitive (cost) they're usually only about a tenner
I'd offer a hand but I notice you're in Scotland
>> Edited by incorrigible on Friday 7th February 16:35
Only put filler onto bare metal, not scored paint, you shouldn't need to score the metal before adding glass/filler
in this case, wire brushing is going to be useless because the arch will be perforated or at best too thin for a decent repair (educated guess)
How much time/money have you got, for about £1 you could do a good repair if you had loads of time and a welder (probably about £20 after filler and primer)
Are arch panels really that prohibitive (cost) they're usually only about a tenner
I'd offer a hand but I notice you're in Scotland
>> Edited by incorrigible on Friday 7th February 16:35
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