Interesting experiment on zinc weld thru primers

[bainzy]

Obviously Electrox seemed to be the best outcome but pound for pound. Where did you stick your money in your restoration?

Im using both - for cavities and seams im using Electrox, for anything not covered or boxed in im using Bondarust.

Main reason for that is that its much easier to get Bondarust to adhere well than Electrox. Not such an issue in inaccessible areas but could be a nightmare if paint lifts through abrasion elsewhere.

When it came back from rust and paint removal, it had been sprayed with a weld through primer. I took the primer off the chassis and sprayed it with Bondarust. Several years on, the weld through primer is rusting underneath on the bodywork (curiously especially where grinding dust falls on it) but the chassis primer I redid with Bondarust is perfect.

 

[bainzy]

I like both Electrox and the Hagmann zinc primer but they do dry matt and are obviously porous, eventually anyway. Is it a trick of the light in the photo or does the Bonda have a shiny finish, similar to epoxy primer?

Yes, it has a bit of a sheen to it and it feels very durable once dry

 

[Exuptoy]

@marlinspike if you check my lads pics of the T4 you will see the stuff painted that day has a sheen still but the stuff further forward from a couple of days previous has a more matt finish and has lightened in colour which might confirm the whole cured after 24-48 hours bit. Although, the rear valance near most had been painted 4 days or so before and there’s still a sheen to it. As I said elsewhere I used it on his last car (Seat Alhambra) and where I hadn’t given it enough time after seam sealer and before Gravitex top coat it caused cracking in the Gravitex where the uncured solvent no doubt started attacking it.
Although I’d be keen to FF the clock 5-10 years to check how this floor had lasted

 

[Dragnet]

Im using both - for cavities and seams im using Electrox, for anything not covered or boxed in im using Bondarust.

Main reason for that is that its much easier to get Bondarust to adhere well than Electrox. Not such an issue in inaccessible areas but could be a nightmare if paint lifts through abrasion elsewhere.

When it came back from rust and paint removal, it had been sprayed with a weld through primer. I took the primer off the chassis and sprayed it with Bondarust. Several years on, the weld through primer is rusting underneath on the bodywork (curiously especially where grinding dust falls on it) but the chassis primer I redid with Bondarust is perfect.

Are you sure it's not just the grinding dust rusting? What's it like if you brush it off? The small particles very quickly return to their joyous final form. Alternatively, I can imagine the large surface area of all the particles rusting could have some kind of galvanic reaction with the weld-thru zinc resulting in reduced protection for the bodywork itself (it's not clear whether the bodywork is rusting beneath the primer or just the dusty parts look rusty). I like the Bondarust for the brushability. There's probably a much thicker coat of it than on the weld-thru, especially if it's just been sprayed by a third party who weren't preparing for it to be left like that.