Galvanising repair

[Plevier]

I have a little trailer (yes it's boaty, carries tools, pressure washer etc!) made of galvanised sheet, the sort of thing Halfords sell. There are patches where the galvanising has gone and there is light surface rust. I'd like to try and preserve it a bit longer, what's more effective, one of the zinc rich coatings like Galvafroid (not cheap!) or Hammerite?
I lean towards Hammerite particularly as I already have some but if the other stuff is a lot better it would be worth it.
Thanks for thoughts.

 

[VicS]

I have a little trailer (yes it's boaty, carries tools, pressure washer etc!) made of galvanised sheet, the sort of thing Halfords sell. There are patches where the galvanising has gone and there is light surface rust. I'd like to try and preserve it a bit longer, what's more effective, one of the zinc rich coatings like Galvafroid (not cheap!) or Hammerite?
I lean towards Hammerite particularly as I already have some but if the other stuff is a lot better it would be worth it.
Thanks for thoughts.

Have in the past found that zinc rich primers are quite effective at least after thorough chemical de-rusting.

However, I'd suggest that you dont use a chemical rust remover, as that may attack the sound galvanizing, but rely on Hammerite coatings, although far from a fan of them, even the old, old original Hammerite .

There is a special Hammerite for applying to galvanized surfaces, (the ordinary stuff might not adhere well), but only to non-rusting surfaces

Edit: they recommend spot treatment with Hammerite No1 Rustbeater, which is non corrosive.

Also for best results anyway prime with 1 coat of Hammerite Special Metals Primer


Take a good look at the Hammerite website!

 

[Plevier]

Thanks Vic
I think I'll have a go with the Hammerite - which is the original stuff. As the galvanising round the rusty patches is certainly wellw eathered, it sounds as though it should be OK without the special primer.
I have got some acid etch primer (1 pack not epoxy) I wondered whether to do it with that first. Is the Hammerite special metals primer an etch do you know?

 

[saltylegs]

I have used both Galvafriod and Hammerite on a bare metal trailer 5 years ago,
The Hammerite was about 50% gone after one year but the Galvafroid is still there and should be ok with another light wire brushing and touch up this spring.

 

[VicS]

Thanks Vic
I think I'll have a go with the Hammerite - which is the original stuff. As the galvanising round the rusty patches is certainly wellw eathered, it sounds as though it should be OK without the special primer.
I have got some acid etch primer (1 pack not epoxy) I wondered whether to do it with that first. Is the Hammerite special metals primer an etch do you know?

It might non stick to the galvanizing without a suitable primer. That's why they produce the special metals primer.

The special metals primer does not appear to be an etch primer,

I cannot comment on whether your etch primer would be a good idea under Hammerite or not. I'd have though it would be though.

If you really have Original formulation Hammerite you'll be lucky if its still usable and unless you have any of the matching thinners you might have difficulty finding a suitable thinner/ brush cleaner. I'd try antifouling thinner but it might not be right.

As I said I'm not a big fan of Hammerite and I know the paint technologists where I worked had tested it and did not think much of it either.

 

[pampas]

Best stuff I have found is International under water primer, use it anywhere, really sticks and if painter seem to do the job of the hard to find products.

 

[VicS]

Best stuff I have found is International under water primer, use it anywhere, really sticks and if painter seem to do the job of the hard to find products.

That is presumably Primocon

The product data sheet seems a bit vague about using it on galvanizing saying, " Pre-prime using an International primer as detailed for specific coating systems".

Elsewhere I found the recommendation to preprime with etch primer..... probably from an old data sheet as International Yachtpaints no longer offer an etch primer.

But perhaps PA10 is the answer http://www.yachtpaint.com/sgp/diy/products/primers/pa-10.aspx.


Could always consider regalvanizing

 

[BERT T]

I would personally stay well clear of Hammerite as it's not what it used to be. Recently I have been using Rustoleum High Performance range, they have four different paints suitable for galvanized surfaces.
http://www.rustoleum.com/product-catalog/industrial-brands/high-performance/

 

[Plevier]

It might non stick to the galvanizing without a suitable primer. That's why they produce the special metals primer.

The special metals primer does not appear to be an etch primer,

I cannot comment on whether your etch primer would be a good idea under Hammerite or not. I'd have though it would be though.

If you really have Original formulation Hammerite you'll be lucky if its still usable and unless you have any of the matching thinners you might have difficulty finding a suitable thinner/ brush cleaner. I'd try antifouling thinner but it might not be right.

As I said I'm not a big fan of Hammerite and I know the paint technologists where I worked had tested it and did not think much of it either.

Shocked to realise my vintage Hammerite is 21+ years old!! It had thickened slightly in the tin. By trial and error I have found some epoxy primer thinner (Jotun 17) seems compatible with it - the MSDS tells me that is 50-75% solvent naphtha (isn't white spirit more or less that?) 20-25% xylene 15-20% butan-1-ol and 3-7% ethylbenzene.
Hammerite used to say you only needed to prime galvanising if it wasn't olda nd weathered, this definitely is. Anyway any overcoating of galvanising will be accidental so not really too bothered, I just want something on the rusty patches.

Fingers crossed! If it comes off quickly I'll try something else, nothing lost.

Thanks to all for comments.

 

[Birdseye]

I have a little trailer (yes it's boaty, carries tools, pressure washer etc!) made of galvanised sheet, the sort of thing Halfords sell. There are patches where the galvanising has gone and there is light surface rust. I'd like to try and preserve it a bit longer, what's more effective, one of the zinc rich coatings like Galvafroid (not cheap!) or Hammerite?
I lean towards Hammerite particularly as I already have some but if the other stuff is a lot better it would be worth it.
Thanks for thoughts.

In work ( we produced galvanised fittings ) repairs always used galvafroid.

 

[Hydrozoan]

Another possibility is Zinga: http://www.zinga-uk.com/product-range/zinga. I don't know how cost/area compares with Galvafroid (Zinga is certainly not cheap either), but here's Zinga's own take on the technical comparison: http://www.zinga-uk.com/uploads/Tech_sheet_09___Zinga_vs_Galvafroid.pdf. I have no connection except as a satisfied user (on an anchor).

PS They say it has unlimited shelf life and pot life - which judging by your 21+ year old Hammerite may be particularly attractive to you .

 

[Plevier]

Another possibility is Zinga: http://www.zinga-uk.com/product-range/zinga. I don't know how cost/area compares with Galvafroid (Zinga is certainly not cheap either), but here's Zinga's own take on the technical comparison: http://www.zinga-uk.com/uploads/Tech_sheet_09___Zinga_vs_Galvafroid.pdf. I have no connection except as a satisfied user (on an anchor).

PS They say it has unlimited shelf life and pot life - which judging by your 21+ year old Hammerite may be particularly attractive to you .

Good point thank you but at 67 I don't expect to be interested in 21 years time.
The Hammerite came from my Dad's garage in 1994. No idea how long it had been there.

 

[Hydrozoan]

Good point thank you but at 67 I don't expect to be interested in 21 years time.
The Hammerite came from my Dad's garage in 1994. No idea how long it had been there.

Jus' jokin' - at 64, the same thought was in my mind as I wrote! (But I did not like to make any assumptions about you, of course.)

More seriously, Zinga may be good for periodic touching-up as it (IIRC) is claimed to 're-dissolve' into itself on repeated application (and has a long shelf life).