Interesting experiment on zinc weld thru primers

[Exuptoy]

I’ve been using Bonda Rust Primer for a few years now and seriously rate it, (many 5* reviews), but decided to have a google search and found it’s been around since the 60’s and is held in very high regard by vehicle restorers.

However, what I didn’t know was it can be used as a weld through primer too.
This test was thought provoking.

Practical Bodging 2024 Resistance Weld Through Primer Test

Inspired by the magazine articles comparing various products for rust proofing performance, I thought I'd have a bit of fun and try a test with some of the paints I'd bought and used over the years. I've always been curious as to what happens under the panels over time when resistance spot weldin...

sideways-technologies.co.uk

 

[Pond frog]

I’ve heard a few good reports of bonda rust prima so I thought I’d try it and it turned into a complete disaster rust came through in a few days and I had to strip the paint back to bare metal and start from scratch. I haven’t touched it since.

 

[dieselsamurai]

Must have been a bad batch or bad prep as ive been using it for years, stuff ive restored for my CUCV truck has been in storage for 10+ years nothings come through

 

[Pond frog]

Maybe I just had a bad batch it was all brand new clean steel so I can’t see prep was the issue, I would have expected less rust on unprotected steel.
It only takes one bad experience of a product to put you off for good but maybe I should give it another go.

 

[Exuptoy]

My lads efforts with it today.

 

[steveo3002]

ive used it on and off , seems pretty good apart from you have to be carefull further solvent product's dont upset it , i stonechipped over it once and it pickled up but thats my fault

tend to stick with epoxy now as its cured in no time and doesnt go off in the tin like bonda

 

[Exuptoy]

Not much chance of it going off with the amount of work we have to do
Apparently in needs 24h to fully cure.

 

[marlinspike]

Reading the whole link it looks like Electrox was the best rust resistant one though not as good as a weld thru primer.

 

[Exuptoy]

It is good but not cheap in comparison to Bonda imo.
I used Electrox on the Seat and a 750ml tins will have a fair percentage of propellant in there too and Bonda goes on very well and it’s fairly thin and it does encapsulate the metal unlike other primers which are kind of breathable.

 

[marlinspike]

I've used the Electrox aerosols and found it pretty good but yes it's very pricey. A couple of years ago I found a graffiti shop clearing out Hagman 90% zinc primer at £2 a can so I bought a few cans. It seems as good as Electrox so far but you never know until a few years down the line. I like all the various Bilt Hamber stuff I've used but the cost plus p and p really adds up. I wish Halfords would sell it.

 

[Exuptoy]

I get that.
TBH though, the manufacturers never put anything like the work into building a vehicle that us as restorers put into them and yet lots are still on the road. Some just need more work than others.

 

[PhillipM]

I've used the Electrox aerosols and found it pretty good but yes it's very pricey. A couple of years ago I found a graffiti shop clearing out Hagman 90% zinc primer at £2 a can so I bought a few cans. It seems as good as Electrox so far but you never know until a few years down the line. I like all the various Bilt Hamber stuff I've used but the cost plus p and p really adds up. I wish Halfords would sell it.

If you use enough of it trade accounts are 30% off for a box...

 

[Keithmac]

I've had great results with this for weld though, two different Nozzles and dries relatively quick.

As said Epoxy primer is had to beat after all the welding has been done.

 

[Dragnet]

I’ve heard a few good reports of bonda rust prima so I thought I’d try it and it turned into a complete disaster rust came through in a few days and I had to strip the paint back to bare metal and start from scratch. I haven’t touched it since.

Peculiar. Did you mix it thoroughly, as that's fundamental I believe. I've had it on bits of MGB in an open car port for a few years and it looks just like when it went on. The bits where it isn't have gone pretty rusty...

 

[Pond frog]

Peculiar. Did you mix it thoroughly, as that's fundamental I believe. I've had it on bits of MGB in an open car port for a few years and it looks just like when it went on. The bits where it isn't have gone pretty rusty...

It was quite a while ago so I can’t really remember but that could well be the explanation user error seems more likely than a random bad batch, the metal prep was fine so lack of mixing could have been the problem

 

[bainzy]

I wish I'd have given the bondarust more time to cure before doing that test (the write up was mine) as it probably wasn't fully hardened before immersing it. I also put the write up on this forum, got loads of suggestions and even some things to test sent to me in the post like 3M panel bonding so will be updating it once life calms down a bit.

 

[Exuptoy]

I wish I'd have given the bondarust more time to cure before doing that test (the write up was mine) as it probably wasn't fully hardened before immersing it. I also put the write up on this forum, got loads of suggestions and even some things to test sent to me in the post like 3M panel bonding so will be updating it once life calms down a bit.

No way….thats awesome! Well done

 

[Exuptoy]

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

 

[fizzy]

The main problem with a lot of these products is that they often change over the years due to constantly changing environmental laws. Just because it worked great 20 years ago doesn't mean it will now

 

[marlinspike]

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?