Rain and primer.....help!!!!

[Amphibian Man]

Hello folks,

I am in the process of treating the roof of my narrowboat. I neutralised the rust with Vaclan. Then I applied the primer undercoat yesterday.. All well and good. I guess it had about 12 hours to dry but then it rained. Should I be concerned or am I worrying over nothing.?

Thanks.

[MtB]

8 minutes ago, Amphibian Man said:

Should I be concerned or am I worrying over nothing.?

 

I'd have thought the primer undercoat would be fine after 12 hours of drying time. What undercoat exactly is it? 

[Alan de Enfield]

8 minutes ago, Amphibian Man said:

Should I be concerned

 

Yes.

 

Undercoat is generally porous even when dry so it will have absorbed the water .

You should not now paint on top of it.

 

 

[MtB]

5 minutes ago, Alan de Enfield said:

Undercoat is generally porous even when dry

 

 

But it isn't 'dry'. Its only 12 hours old and probably still soft and full of solvent. 

 

 

[Alan de Enfield]

1 minute ago, MtB said:

 

 

But it isn't 'dry'. Its only 12 hours old and probably still soft and full of solvent. 

 

 

 

I guess that it will depend on the 'drying time / overcoating time specified on the tin, and, the ambiant temperature and humidity for the 12 hours it was left.

It will have lost some of its volatiles(VOCs) evaporate pretty quickly.

 

When we had a boat painted I had discussions with the painter and he said that undercoat will even absorb moisture from the air (high humidity) and it is imperative that you get a top coat on ASAP.

If the undercoat gets the chance to absorb any moisture and it is painted over, when the sun get on the paint the water bubbles 'boil' and you get micro-bubbles in the paintwork and it look similar to Orange peel.

 

Just what I was told by a professional boat painter.

[rusty69]

Having just painted my roof, I can advise that there are only 2 clear days available for painting outside in the UK. For the rest of the year, it is either:

 

Too hot

Too cold

Too wet

Too windy

Too dusty

Too blossomy

Too leafy

Too insecty

Too grass cuttery

Too icy

Too snowy

Too dewy

Too much hassle.

 

Do it inside.

Edited May 19, 2023 by rusty69

[Amphibian Man]

Thanks everyone. I am afraid the horse has bolted. I used teamac primer over the whole of the roof. It was warm yesterday and dried to the touch almost immediately. I naively thought once the primer/undercoat had dried it could be more or less forgotten about until ready to overprint.

[dmr]

If you ever do this again..(and you likely will).......

Vactan is only a second best/compromise when its not possible to remove the rust, ideally remove all the rust and do not use a rust converter, and if there is any chance of rain then consider using Bondaprimer which is waterproof, in fact probably use Bondaprimer anyway.

[MtB]

45 minutes ago, rusty69 said:

Having just painted my roof, I can advise that there are only 2 clear days available for painting outside in the UK.

 

Usually yesterday and the day before, in my experience.

 

 

[rusty69]

3 minutes ago, MtB said:

 

Usually yesterday and the day before, in my experience.

 

 

Luckily I did mine yesterday and the day before despite a 50% chance of rain forecasted. It didn't.