How to prevent rust after new hydro stamp?

[scubafanatic]

Just took a pair of Scubapro (Faber) LP 76's in for hydro....they are still in original hydro, but the visuals are expired and the hydros expire 03/2004 so I thought I'd go ahead and do them now so they'd be dive-ready for the 2004 season. (small twinset)

Question: the tanks are in great shape, the insides look as new as the day they were manufactured, a few cosmetic sctatches on the outside....but I'm worried about the outer layer being compromised by the hydro stamp. There will be bare metal exposed, I assume, so what can be done to restore the full measure of protection to the hydro stamp areas?

Any tips are appreciated...also, anything I need to look for if I decided to get the whole tank repainted? Is there a special paint or method I need to ask for to get the best results?


Karl

 

[drbill]

Interesting question. I dive steel and have not seen any problems in the vicinity of my hydro stamps, and one tank is 20 years old.

Dr. Bill

 

[DA Aquamaster]

The galvanized coating the covers the tank essentially operates by preventing the exchange of ions that causes rust. The effect works a lot like the sacrifical annodes on boat motors and boat hulls and a small break in the coating is still "covered" by the process as the whole area is conductive.

Some hydro testers will cover the freshly stamped marks with a silver colored paint, partially for cosmetics and partially for some additional rust protection. Paint sticks really well in the recessed nooks of the stamp and that alone will seal the area from contact with water and prevent any ion exchange.

 

[scubafanatic]

Thanks for the info, DA Aquamaster and drbill! I've seen a variety of different hydro stamps.......one 'style' of which appears to involve some sort of metal grinder to carve/blast away a rectangular area in the paint, and then stamp the tank within that cleared out area. If that happens, it's hard to imagine the thin surface galvanized layer remaining intact...sure hope it doesn't come back from hydro that way! Hopefully they'll not 'clear' an area, merely impress a new stamp, and paint it over .

I'll keep you posted on how it turns out....but as of now I'm still nervous...these are my 1st used tanks, and the 1st time I've had to hydro anything...fingers crossed...should be back from the shop late this week.

Karl

 

[Snowbear]

DA Aquamaster once bubbled... Some hydro testers will cover the freshly stamped marks with a silver colored paint, partially for cosmetics and partially for some additional rust protection.

Is probably a cold galvanizing product such as "Zinc-it." It's available in a rattle can from your friendly neighborhood harware store if for some reason the hydro place didn't use it...

 

[Norm]

Grinnell does most of our local hydro's and they always spray over the new stamp with cold galvanizing. It is barely detectable. Maybe you can buy a spray can of this locally? If not, perhaps a can of clear spray lacquer?
Norm

 

[scubafanatic]

Hi Norm,

Got both tanks back from hydro.......just dove them for the 1st time at the quarry this afternoon....worked great......as doubles they're big enough to get decent bottom times, but small enough to handle topside.

The hydro facility cleared away a small bare area in the paint on both tanks, them stamped them....but I simply covered the spots with duct tape for today to keep them dry...I'll go to Home Depot tomorrow, get some Zinc-It and a small spray can of black paint and make the patch permanent.


Karl