Temporary fix for rust spots on steel deck

[phipseml]

Hi all,

Imagine it's close to freezing point and you have a time window of about 2 to 3 hours between rain events, just enough to let the deck dry. It's about 2 weeks left before winter kicks in, which means constant below freezing and tons of snow and moisture, conditions which will last 6 months. You have a few rust spots on deck, nothing serious, the usual suspects under one of the hatches, close to water intake, the odd spot in the middle of nowhere etc. What would you do?

Cheers,
Phil

[Wotname]

Originally Posted by phipseml

Hi all,

Imagine it's close to freezing point and you have a time window of about 2 to 3 hours between rain events, just enough to let the deck dry. It's about 2 weeks left before winter kicks in, which means constant below freezing and tons of snow and moisture, conditions which will last 6 months. You have a few rust spots on deck, nothing serious, the usual suspects under one of the hatches, close to water intake, the odd spot in the middle of nowhere etc. What would you do?

Cheers,
Phil

Well Phil, I would probably sit back and have a beer or perhaps something stronger.

Failing that, I just might warm up the steel with a hot air gum, whack on a bit of zinc rich primer, play the hot air around the paint (very gently) and cover with some plastic film. Do each spot between showers and then think about that beer again.

There is always next spring / summer to redo it

[Warby12]

Used to have a steel boat. Heard but Never tried it but makes sense to me for a temporary fix: 5 minute araldite epoxy

[Lake-Effect]

Assuming you have a 'dry' window of a few hours, or you can tent the area for long enough, I would wipe the area dry, wipe with fast-drying solvent (eg acetone) to remove grease and oil, use a grinder or wire wheel to remove as much rust as possible, wipe down with solvent again to clean and dry, and either primer the area or use a 'rust' paint like Tremclad or Rustoleum. Protect from water til it dries.

It's not a permanent fix, you just want something protecting the area over the winter, til you can properly fix the area when it's warm and dry again.

[a64pilot]

No ospho?

[Lake-Effect]

Originally Posted by a64pilot

No ospho?

Grinding down to bare metal is preferable IMHO, but Ospho or another phosphoric acid treatment could work too. I think you still need to cover it with paint to last the winter.

[barnakiel]

Angle grinder,
wipe with acetone,
cover with quick dry primer,

you may find nitro primers

b.

[a64pilot]

Originally Posted by Lake-Effect

Grinding down to bare metal is preferable IMHO, but Ospho or another phosphoric acid treatment could work too. I think you still need to cover it with paint to last the winter.

You may be right, I'm not used to those kind of winters. I was thinking slap some ospho on it and deal with it in the spring, a pure temp patch job to keep from rusting further, not a repair. Need to remove it in the spring and do a proper repair.

[SVTatia]

Originally Posted by Lake-Effect

Assuming you have a 'dry' window of a few hours, or you can tent the area for long enough, I would wipe the area dry, wipe with fast-drying solvent (eg acetone) to remove grease and oil, use a grinder or wire wheel to remove as much rust as possible, wipe down with solvent again to clean and dry, and either primer the area or use a 'rust' paint like Tremclad or Rustoleum. Protect from water til it dries.

It's not a permanent fix, you just want something protecting the area over the winter, til you can properly fix the area when it's warm and dry again.

Dead on. This exactly what I used to do, even at sea. Just put a pause on the corrosion process before you can do it properly. Works great.

Originally Posted by Lake-Effect

Grinding down to bare metal is preferable IMHO, but Ospho or another phosphoric acid treatment could work too. I think you still need to cover it with paint to last the winter.

I used Ospho extensively but it gets removed by water, so you are right again, it would not last the winter. I would use Ospho as a neutralizer then when dried put a coat of any paint to water proof it.

[hpeer]

IIRC, some of the Ameron products have some pretty low application temps.

And, frankly, I don't know if it matters if the epoxy gets wet once it's been applied. Maybe someone else would know, what's the harm of a little water as it dries?

[phipseml]

Hi there, thanks for your replies.

It seems the general opinion is to actually go and do something rather than wait until the winter is over. So it seems that half a year delay in touching the rust spots is considered long enough to worsen the problem, even at freezing temperatures.

As I understand it, removing paint and rust and putting ospho/ primer on is already the first step in a repair I would do during summer. The further steps would just be to add a few layers of paint over that primer. DO I get that right?

My concern here is, that the air will be very moist, and it will be very cold, i.e. somewhere between 0 and 5 degC. That might be bad for the primer and paint (whatever philosophy you follow Rustoleum etc or high tech epoxies) to dry - which is still better than doing nothing and redo it in summer?

I think I'll lean back first and have a beer to think about this....

Phil

[conachair]

I've used owatrol oil before to keep rust spots in check until a decent repair can be done. Dries very hard , seems to work OK for a while. Doing a good repair job in the cold isn't easy.

[SVTatia]

Originally Posted by phipseml

...My concern here is, that the air will be very moist, and it will be very cold, i.e. somewhere between 0 and 5 degC. That might be bad for the primer and paint (whatever philosophy you follow Rustoleum etc or high tech epoxies) to dry - which is still better than doing nothing and redo it in summer?

I think I'll lean back first and have a beer to think about this....

Phil

You just want to neutralize the rust and pause it for a few months. In my opinion, and what I used to do was to Ospho it (new verb) followed by any kind of paint - until you can get to it in the spring. If its too cold, use a hair dryer, or heat gun for a few minutes on it before and after (not too close).

Afterwards, if its too cold for beer, you may have something more potent, no?

[UNCIVILIZED]

As to the moisture & cold issue when it's curing, can the metal in question be warmed from the other side? I'd imagine that doing such would both speed up the cure, as well as ward off at least some of the moisture (temporarily).
Just cozy up a halogen light or space heater near to the spot, from the inside (just not so close that you damage the interior finish or start a fire). That, or some heat tape, warm bricks... you get the idea.

And as to what to put on the rust, what about something like POR 15, or Rust Bullit? In one of my new "hobbies", keeping the truck alive, it seems like some guys swear by the stuff - though I haven't had time to research it in depth myself.

Or if you're not overly concerned with cosmetics, you could again, do the quick & dirty prep, & then perhaps smear on some coal tar or similar.
Just don't put it anywhere it'll get splashed, if the boat's still in the water, or the Green guys will likely be all over you.

[phipseml]

Thanks for your reply. I think warming up from the inside is a good idea - that might keep the affected area warmer and drier for a bit longer than just hot air gunning it from the outside for a short period of time. Our hull is very well insulated, though, and I think that might be difficult. Even during the last warmish days here I am a bit worried about clear nights with lots of condensation while the paint cures, but maybe a tarp will be enough to keep the infrared from escaping and condensation to form.

I have read about POR 15 elsewhere in this forum, and it was recommended, but nowhere to find here. I can't find Ospho either (by now I've been to all shops and mailorders), but plenty of similar products based on phosphoric and other acids which I will try.

I did finally find Rustoleum primers, which are also often mentioned as a great alternative to two pack products, and I will try that one of these days. I'll post here how it goes - this will be my first steel job.

Cheers,
Phil