How long can you leave your boat in the elements with grey oxide on?

[Sphinx123]

Hi,

 

I've painted my boat in grey oxide. I can't paint the undercoat and top coat on for another 6 weeks or so... How long can you leave your boat in the elements with grey oxide on? Will it be okay? The plan is to take it back under cover in about 6 weeks, sand it, undercoat it x2 then top coat it x2. It has to come out from under cover tomorrow so I only have today to paint it with the final coat of oxide (it has already had one coat, plus filler/stopper in areas.)

[Jen-in-Wellies]

What maker/type of paint is it? Grey oxide doesn't narrow it down. Assuming this is a primer, there are some primers that are better than others at surviving a delay before under and top coating, so without that, it is hard to say.

Edited September 9, 2022 by Jen-in-Wellies

[Sphinx123]

2 minutes ago, Jen-in-Wellies said:

What maker/type of paint is it? Grey oxide doesn't narrow it down. Assuming this is a primer, there are some primers that are better than others at surviving a delay before under and top coating, so without that, it is hard to say.

It's grey oxide primer by Premium Paints: https://premiumpaints.co.uk/products/paintmaster-anti-corrosion-metal-oxide-primer-heavy-duty-20-litre?currency=GBP&variant=14649009307690&utm_medium=cpc&utm_source=google&utm_campaign=Google Shopping&gclid=Cj0KCQjwyOuYBhCGARIsAIdGQRMV5-yJA4qBfbVonNYbFN0ANeTE40w5fg1HoNexVgMxqfW3G1p1IWYaAk1YEALw_wcB

[BEngo]

6 weeks outside in autumn without topcoats is far too long, and a recipe for early failure of the paint scheme.  Really paint should be one process, pausing only to allow the paint to dry well enough to prep for the next coat.

 

I assume you mean grey oxide  primer.  If so, most  primer is porous, to encourage the following coats to stick, and is not meant to be left in the weather.  The risk is that the porous primer draws water vapour from the air or rain/dew into the paint.  The following non-porous coats then seal this in, for a while.  Either there will be micro blistering  or rust, or both.  Intr-coat adhesion is not helped by a long delay because the paint cures and there is no chemical bond with the next layer.

 

You can help slow the whole thing down, by drying the primer out thoroughly before under coating.   You will need to get your dock warm  enough that the relative humidity is fairly low- less than 60% and the lower the better, then keep it there for 24 hours before you paint.  Heat lamps to warm the steel help.   You can sand etc during this time.  Consult the paint technical data sheet carefully and stick to its advice.

 

If any rusting has started, it will appear again ,as rust does.

 

N

[pearley]

There is a sailaway moored next to us that has been in primer since launch some 5 months ago. As the marina doesn't allow painting on the pontoons and it's too wide to go through the locks either side of us, it will be interesting to see what happens.

[robtheplod]

1 hour ago, pearley said:

There is a sailaway moored next to us that has been in primer since launch some 5 months ago. As the marina doesn't allow painting on the pontoons and it's too wide to go through the locks either side of us, it will be interesting to see what happens.

You'll wake up one morning and it will be shiny red! 

[David Mack]

2 hours ago, Sphinx123 said:

It has to come out from under cover tomorrow so I only have today to paint it with the final coat of oxide (it has already had one coat, plus filler/stopper in areas.)

I think you would be better painting it with coat of undercoat today, as that will seal against moisture better than another coat of primer.

[MtB]

3 hours ago, David Mack said:

I think you would be better painting it with coat of undercoat today, as that will seal against moisture better than another coat of primer.

 

 

I agree. Why would it need more than one coat of primer anyway?

 

(Not that I've read the technical sheet for your specific paint.) 

[BEngo]

15 minutes ago, MtB said:

 

 

I agree. Why would it need more than one coat of primer anyway?

 

(Not that I've read the technical sheet for your specific paint.) 

Theoretically,   to get the recommended dry thickness of  paint, without having to have excess wet film thickness which takes ages to cure properly and may end up with trapped solvents. (,which later cause big problems)

 

Practically, it is bloody difficult to rub down a single coat without ending up with bare patches. Which are deffoqqqqq not helpful in the primer layer.

 

This paint lark can be technical- as bad as modern boilers🙂

N

[MtB]

2 minutes ago, BEngo said:

Theoretically,   to get the recommended dry thickness of  paint, without having to have excess wet film thickness which takes ages to cure properly and may end up with trapped solvents. (,which later cause big problems)

 

Practically, it is bloody difficult to rub down a single coat without ending up with bare patches. Which are deffoqqqqq not helpful in the primer layer.

 

This paint lark can be technical- as bad as modern boilers🙂

N

 

Given the time constraints on the OP., leave out the rubbing down! 

 

Just get a coat of undercoat on top tonight and finish off out in the wind, rain and dust..... 

 

The correct solution to their problem of course was to have booked a poly tunnel for long enough in the first place, but they are prolly fully aware of this! 

 

 

[IDS]

I was advised by craftmaster tech services dept to strip it off and start again, after mine had been in the open and rained on! If it has been under cover then possibly ok.