pcatterall
Well-Known Member
The previous owner has removed blasted and galvanised the tabernacle. Is there any point in adding paint or is it better left bare. Any special primer/paint ( if 'yes' )
Thanks
Thanks
Painting Galvanised steel. Yes or no ?
- Thread starter pcatterall
- Start date
sailorman
Well-Known Member
i would leave as is, less maintenence.
if you do paint use a calcium plumbate primer
Poignard
Well-Known Member
About 13 years ago I had a new one made and galvanised. I painted it afterwards and it has lasted very well and it looks much better than bare galvanising.
I contacted International Paints Ltd and they gave me a schedule of what paints (theirs of course!) to use. I seem to remember it involved an etching primer followed by some 2-part paints. Cost a lot and I had to buy far more than I needed due to minimum pack sizes. Most of it is still in the garage waiting to explode.
prv
Well-Known Member
Mine's bare galvanised and seems to manage just fine with no treatment of any kind.
The inside got a dosing of sheep fat yesterday, but that was just to help the mast foot slide into place
Pete
The inside got a dosing of sheep fat yesterday, but that was just to help the mast foot slide into place
Pete
Poignard
Well-Known Member
Just to be clear, I painted mine because I didn't like the look of the bare galvanising. I doubt the paint had much protective effect; it's just that ordinary paint doesn't adhere well to galvanised surfaces so a bit of special treatment is needed to make it last (which it certainly has done)
At least that's what the man who sold me the expensive paint told me
At least that's what the man who sold me the expensive paint told me
VicS
Well-Known Member
Provided the galvanizing is in good condition it is probably best left bare.
It can always be re-galvanized if necessary.
If painted then yes a suitable primer is necessary. Maybe, just maybe, Hammerite special metals primer.
Self etching primer was used for many years. No longer the preferred option for aluminium but may still be for galvanizing.
International have discontinued their self etch primer but still say to use one as a pre-primer under Interprotect ( 2 part epoxy primer) for galvanizing.
Paint is far more likely to be damaged than proper hot dip galvanizing.
It can always be re-galvanized if necessary.
If painted then yes a suitable primer is necessary. Maybe, just maybe, Hammerite special metals primer.
Self etching primer was used for many years. No longer the preferred option for aluminium but may still be for galvanizing.
International have discontinued their self etch primer but still say to use one as a pre-primer under Interprotect ( 2 part epoxy primer) for galvanizing.
Paint is far more likely to be damaged than proper hot dip galvanizing.
Tranona
Well-Known Member
Painted mine and the mast band with Hammerite - special primer and normal silver top coat several years ago because it was looking a bit tatty after 40 years. Still looks OK. Would not bother if it is newly hot dipped - it will probably see you out (unless you are a youngster!)
pcatterall
Well-Known Member
Yes only 69! The regalvanised item looks good, I was just worried that if there were any poor areas then painting now might help.
Thanks all.
Thanks all.
MM5AHO
Well-Known Member
Painting galvanized steel has two effects. One is to prolong the corrosion resistance life of the coating system, and the other for aesthetics.
Galvanizing will last a long time, but that time is entirely dependent on the environment into which you put the steel.
Galvanizing protects by forming a skin of oxides and carbonates of zinc which in turn protect the zinc, which in turn electrolytically protects the steel. The oxide/carbonate layer re-forms if taken off by abrasion etc, but consumes some zinc in doing so.
To paint galvanized steel it is necessary (not optional) to etch the surface of the zinc first. There are several ways, but the simplest is to use a phosphoric acid brew often going by the name "T Wash". It's not strong acid, and contains some copper in order to turn the zinc black so that you know where you've treated and where you missed. After this dries, paint over the top with an alkyd, or epoxy paint. Disadvantage of epoxy is the lower UV resistance (breaks down in light).
"Hammerite" is not a type of paint, rather a brand. (in the same way that Dulux, Awlgrip etc are brands). Hammerite is owned by ICI, which in turn is owned by Akzo Nobel, the world's largest paint manufacturer.
Other Brands by Akzo include Awlgrip, Dulux, Glidden, Interlux, International Paints, Resicoat, Interpon, Chromadex, Sikkens, Trimetal and many others.
Galvanizing will last a long time, but that time is entirely dependent on the environment into which you put the steel.
Galvanizing protects by forming a skin of oxides and carbonates of zinc which in turn protect the zinc, which in turn electrolytically protects the steel. The oxide/carbonate layer re-forms if taken off by abrasion etc, but consumes some zinc in doing so.
To paint galvanized steel it is necessary (not optional) to etch the surface of the zinc first. There are several ways, but the simplest is to use a phosphoric acid brew often going by the name "T Wash". It's not strong acid, and contains some copper in order to turn the zinc black so that you know where you've treated and where you missed. After this dries, paint over the top with an alkyd, or epoxy paint. Disadvantage of epoxy is the lower UV resistance (breaks down in light).
"Hammerite" is not a type of paint, rather a brand. (in the same way that Dulux, Awlgrip etc are brands). Hammerite is owned by ICI, which in turn is owned by Akzo Nobel, the world's largest paint manufacturer.
Other Brands by Akzo include Awlgrip, Dulux, Glidden, Interlux, International Paints, Resicoat, Interpon, Chromadex, Sikkens, Trimetal and many others.
VicS
Well-Known Member
We know and both my post and Tranona's post referred specifically to Hammerite "Special Metals Primer". Which is a type of paint.
Modulation
Well-Known Member
Not really unless you can't abide the appearance.
The traditional primer for galvanised metal was zinc chromate.
The traditional primer for galvanised metal was zinc chromate.
electrosys
Well-Known Member
Paint ? - yes - the function of the zinc coating is to protect the steel, if necessary by sacrificing itself in the process. So why not protect the zinc coating as well ?
I've painted my galvanised trailer with high-build zinc phosphate primer (although I'm sure any zinc-based primer would have done the same job), and expect it to easily out-live me ...
I've painted my galvanised trailer with high-build zinc phosphate primer (although I'm sure any zinc-based primer would have done the same job), and expect it to easily out-live me ...
stewart9901
New Member
I work on a boat that is 16yrs old, it has several galvanised parts on deck. these areas are still looking good even after the hard life they have had. as mentioned above, unless its the asthetics which are the problem itll be fine without paint.
DownWest
Well-Known Member
One of the previous editors of PBO (G. Taylor? I lent the book and natch...) wrote a good tome on fitting out a bare hull. Good basic info on GRP work and other stuff, inc. galvanizing. He said that the sum of the protective effects of painting and galvanizing were more than their separate ones. So worth it. IIRR, there was no technical explanation of the effect.
But a galv. tabanacle looks OK on the right boat. I did see one that had wood laminated on....a real wood one would have been too clunky if strong enough.
But a galv. tabanacle looks OK on the right boat. I did see one that had wood laminated on....a real wood one would have been too clunky if strong enough.