[scubalegg]

I recently removed my halo from my twins to find half the paint coming with it around the neck! There isn't any rust and looks nice and shiny... What is the best way to repaint a cylinder. Will something like Hammerite smooth from a rattle can be enough as its only a small area

Thanks for any replies

 

[Richard_severn]

Don't re paint them my buddy got a set of twins recently that were used without boots and he decided to paint the bottoms so he got a proper primer and paint etc .i told him it wouldn't work but he painted them when he took the boots of next they took of all the new paint with them.

I stripped a 7l cylinder down to the zinc coating sanded it nicely cleaned it all cleaned it again sprayed it with zinc etch primer a few coats flatting back between them i then did the same with a matt black paint flatting back waiting the correct time between coats then i sprayed them with several coats of lacquer it looks lovely but if i flick it hard enough you can take the paint off.

You can cover it with clear nail polish if you want to that seems to work. or just give up no matter what you do to them care wise they will get scratched eventually aslong as you rinse them off after a sea dive and dry them they shouldn't rust thats what im doing and if you get any paint bubbles scrape the bubble off or you get water under it and a big deep rust patch

best of luck

 

[dynarob]

I stripped a 7l cylinder down to the zinc coating sanded it nicely cleaned it all cleaned it again sprayed it with zinc etch primer a few coats flatting back between them i then did the same with a matt black paint flatting back waiting the correct time between coats then i sprayed them with several coats of lacquer it looks lovely but if i flick it hard enough you can take the paint off.

That's because 1K 'etch' primers are basically a con. There is nothing 'etch' about them. If you want good adhesion then you need to use proper 2K etch (with all the safety precautions that entails) or use a direct adhesion paint straight onto the metal.

FWIW If I was doing it I would go for a clear over base finish - using 2K lacquer. The lacquer is very tough (same stuff they use on car bodywork) and will provide as much protection as you can get.

 

[Richard_severn]

I thought the sale of 2k paints was being restricted ? I looked at 2k lacquer and I was just going to spray that over the Zinc without bothering with colour

 

[dynarob]

2K is / should be difficult to buy as an individual as it is pretty nasty stuff due to the isocyanates in it. For industrial use with a filtered spray booth and air fed mask it is fine and there don't appear to be any restrictions. It is readily available on FleaBay though.

 

[scubalegg]

Thanks for the replys, I don't have any type of spraying equipment so everything is from a rattle can... I thought about the nail varnish but the hole cyclinders needed to be sprayed so this isn't really practicle, so I got some hammerite and layered them up flatten back and layer some more, but as mentioned before it is chipping very easily so I need to find someone way to harden it, would normal lacquer from a rattle can do this or do I need to get down a body shop and have them give them a spray?

 

[William Ulsterman]

Resprayed my pony recently. Took down to bare metal. Two layers of primer. Two coats of plastikote and two layers of clear lacquer. Fine so far. No rust coming through. Just take your time spraying

 

[Dive dog]

My cylinders were shot blasted and then had an epoxy base put on before powder coating. They have lasted two years and still look good.
Handy having a mate as foreman at a powdercoat/zinc coat company.

 

[dynarob]

My cylinders were shot blasted and then had an epoxy base put on before powder coating. They have lasted two years and still look good.
Handy having a mate as foreman at a powdercoat/zinc coat company.

Heating pressure vessels up to nearly 200°C is probably not to be recommended. Shame as powder coating would definitely be the cheap way of painting dive cylinders.

 

[Woz]

I think you can heat up cylinders to "quite hot". There's a temperature in the testing standard somewhere and I was surprised at how hot it was.

There is an industry standard for paint systems for corrosive environments. C5 I think is marine which has a grit blast, zinc phosphate primer, 2 base coats then 2 polyurethane top coats.

Cylinders are a bit different though as they expand and contract as the cylinder is pressurised and emptied. Then the paint falls off if it's not flexible.

 

[Woz]

Found it. 300°C for steel cylinders, ally cylinders much lower depending on the type of alloy. 80 or 150°C with limited exposure times.

 

[Dive dog]

There you go. 180 degrees for just 18 mins for the powder coating will not do any harm. Were tested just after and were fine and two years later and still fine.