Wire Brush on Steel Tank?

[USFishin]

I have 2 HP 119 galvanized steel tanks that are only a little more than a year old. One of them is perfect in condition but the other has some white spots on it. They're almost as if the tank didn't get rinsed after a dive and there's salt deposits on it. I wash my tanks after every time I use them so I don't know how the spots got there. I've tried scrubbing the tank with a nylon brush and some soap, etc and the spots won't come off. I tried a little test spot with a brass wire brush and a little spit. I swirled the brush around a little bit and then wiped it down and let it dry. The spot that I cleaned with the wire brush doesn't have the white spots on it anymore. I don't want to damage the finish of the tank though. Will the brass wire brush damage the galvanized finish? If so any other suggestions? If I can't safely get them off it's not a big deal I just hoped to keep my fairly new tanks looking new.

 

[Stu S.]

I just took a peek in the garage. I have the same thing on one of our tanks. It looks like some of the finish from the last boat we were on rubbed off in it. We are not going to mess with it.

The galvanized coating is a lot softer than the steel brush. It would be easy to brush right through it. Then, the bare steel would rust.

 

[USFishin]

I used a brass wire brush since it's softer than a steel wire brush. Not sure if the brass brush will rub off the galvanized finish or not though. The tank looks like it went on a dive and has water spots on it that never got washed off.

 

[vintagediver]

Don't worry about it...
Shows they have been used and gives them charactor...
Who wants shiny new tanks...

 

[divinginn]

It just adds character to the tanks,you did good using brass instead of steel,would have left rust specks.

 

[USFishin]

It's not a big deal if the spots don't come off but I'd like it to not look like I forgot to wash it or something. Will the brass brush take off the galv finish?

 

[Belmont]

It's some of the zinc coating that has oxidized more in those spots. It's normal for zinc to oxidize since it is how it creates a protective film that keeps oxygen from reaching the steel underneath.

If you keep removing the oxide you will reach the base metal and then your tanks will certainly not look "new".

The same thing happens with aluminum tanks, they start shiny and after a certain time in contact with the oxygen in the air it forms a dull grey aluminum oxide coating. That oxide if very resistant to corrosion.

 

[Eric Sedletzky]

I wouldn't mess with it.
The way zinc galvanizing works is that it is a sacraficial metal. The zinc is supposed to oxidize. If you constantly brush or scrub off the white rust (zinc corrosion) you will shorten the life of the zinc coating thus eventually exposing the steel, and when that happens you're screwed; you'll have to have the tank proffesionally painted and that will never be as good as factory galvanizing. The oxidation you see will only get so bad. Just rinse the tank well after salt water exposure and make sure you take the boot off each time and get all that rinsed. That's where I see most of the red steel rust start is under the boot.
If you see red rust starting on the rest of the tank that means you've burned through the zinc and have exposed the steel,... not good.

Leave it alone and be happy.

E

 

[Stu S.]

Seeing the photo, I appreciate your concern. Many of us have those tanks. We see maybe a slight bit of oxide growth. That one probably had a little rougher surface than the rest. Considering the price, one would expect them to look like solid gold.

99% of dive equipment is to be cleaned with nothing more than mild soap and water. These tanks fall into that category. Otherwise, it is more harm than good.

Consider taking those big tanks down to Venice, FL. Stay down all day and get a bushel of shark teeth.

 

[captain]

I have some galvanized steel tanks that are 50 years old and all I ever did is rinse them with fresh water. The less you mess with the galvanize the better, remove the boot and rinse and dry.