Why are paints sold with drying times at unrealistic temperatures?

[Greenheart]

Are most boats painted indoors? Otherwise, it hardly seems relevant to advertise drying times at 20°c. Even if days reach 20°c, they're unlikely to average over 16°c outdoors...

...and in spring in the UK, an average of 10°c is much more likely. Touch dry 4 hours, 'hard dry' 12 hours, re-coat 16 hours...during which, 20°c may only apply for 30 minutes.

Assuming, let's say, the coming week is used, using oil-based one-pack paint...if daytime temperatures barely lift into double figures, how much longer will drying take?

My pot of undercoat is supplied in the UK with all-English labelling...yet there's no extension of drying times for English weather. Anybody know how long it'll take?

 

[nigelmercier]

I have the opposite problem on my boat

 

[Greenheart]

Forgive me if I don't sympathise! :cold:

But it seems odd, if manufacturers are aware that temperature affects drying, that they don't supply drying times at 10°c, 20°c and 30°c...or doesn't it vary all that much?

I'm mostly concerned that by the time I cover the boat at the end of a cool dry March day, the cover will stick to the new paint.

 

[VicS]

Forgive me if I don't sympathise! :cold:

But it seems odd, if manufacturers are aware that temperature affects drying, that they don't supply drying times at 10°c, 20°c and 30°c...or doesn't it vary all that much?

I'm mostly concerned that by the time I cover the boat at the end of a cool dry March day, the cover will still to the new paint.

Dunno what paint you are using but International give "touch dry", "dry to walk on" and min and max overcoating times for their Deck paint ( Interdeck) at various temperatures from 5°C to 35°C.
http://www.yachtpaint.com/MPYACMDatasheets/Interdeck+eng+A4+Y+20130213.pdf

If the times are not given in the Product datasheet for the paint you are using I suggest you contact the manufacturers and ask them

 

[prv]

Professionally, boats generally are painted indoors if at all possible. Ours certainly was - mast off, surface prepared in the main shed, then wheeled into the big spray bay for painting. Or a temporary tent is erected around the boat and portable heaters deployed. I think most people painting a dinghy would try to do it in a garage or similar.

I would not try to put a cover on a boat I had just painted. Do the job on a day with no rain forecast, and leave the cover off for that night.

Dew can be a problem as well.

Pete

 

[Greenheart]

Thanks Vic, Pete. Paint is from 'Supplyshed' and to be honest it hasn't arrived yet, from somewhere northern...but data given on the internet only lists very southern temperatures!

I guess I can leave the cover off overnight...but at temperatures in single figures, isn't the paint likely to stay so gloopy that I find swarms of nocturnal insects adhered in the A.M.?

Does dew affect oil paints applied before noon? I guess the previous night's damp needs airing-off, but if paint is applied in the morning, will the following night's dew be a problem?

 

[prv]

I guess I can leave the cover off overnight...but at temperatures in single figures, isn't the paint likely to stay so gloopy that I find swarms of nocturnal insects adhered in the A.M.?

Maybe.

Does dew affect oil paints applied before noon? I guess the previous night's damp needs airing-off, but if paint is applied in the morning, will the following night's dew be a problem?

If you put it on early enough in the day you should be ok. I would occasionally get a coat of varnish on Kindred Spirit's mainmast finished with a matte effect due to dew, if I didn't pitch up to work early enough and then took too long over the preparatory sanding.

Pete

 

[VicS]

Thanks Vic, Pete. Paint is from 'Supplyshed' and to be honest it hasn't arrived yet, from somewhere northern...but data given on the internet only lists very southern temperatures!

I guess I can leave the cover off overnight...but at temperatures in single figures, isn't the paint likely to stay so gloopy that I find swarms of nocturnal insects adhered in the A.M.?

Does dew affect oil paints applied before noon? I guess the previous night's damp needs airing-off, but if paint is applied in the morning, will the following night's dew be a problem?

I guess insects could be a problem although probably not so much now as it will be once the weather is warmer.

Certainly dont apply the paint to a damp surface or if the substrate is less a than about 5° about the dewpoint.

Dew on the fresh paint could cause a dullness or bloom but presumably a deck paint is not a high gloss so maybe less of a problem than it would be to a gloss paint.

Dunno why you are choosing to buy from Supplyshed but it strikes me that if you are paying P&P then you will not be saving any money compared with buying International paint over the counter from somewhere like Force4

 

[Lakesailor]

I guess I can leave the cover off overnight...but at temperatures in single figures, isn't the paint likely to stay so gloopy that I find swarms of nocturnal insects adhered in the A.M.?

Does dew affect oil paints applied before noon? I guess the previous night's damp needs airing-off, but if paint is applied in the morning, will the following night's dew be a problem?

Yes.
At this time of year the increase in humidity before dusk is enough to bloom the paint. Personally I wouldn't try painting until the temp is reliably over 12°C.
Don't expect paint to be hard enough to cover for a few days. Touch dry and hard are comparative terms.
I painted a Mini with cellulose. Summertime. lovely. Cellulose goes off in minutes but remains soft for a while. I didn't appreciate how long it takes to harden properly. A couple of days later a neighbour came around and we were chatting. I leant on the roof of the car with a shirt sleeve. When I took my arm away the weave of the shirt was embedded in the paint.
I had to respray the roof. Luckily on a Mini that is easy.

Marine brushing paints are mainly enamels and take as long as a couple of weeks to get properly hard. When painting dinghies and such I leave them alone after painting for a least 2 days and then am careful about handling them.If you can't get it under cover, make a tent over it.

 

[Greenheart]

Thanks gents, sound advice I'm sure. I'd been wondering about a tent, an hour ago. I reckon I'll leave painting a few weeks until the temperature (even on dull days) is 5° warmer.

It's not like I don't have any other jobs to do!

I was pretty careful, looking for economical, decent quality paint. I couldn't find International undercoat for less than double what Supplyshed cost - and postage was only a fiver.

 

[TQA]

Well for me they are important as my average temp exceeds 20c and is often around 25c.

 

[Iliade]

I'm waiting for a 40 degree day to paint my hull...


... been waiting for a few years now.

 

[Lakesailor]

You'll end with a series of rollers stuck to the hull

 

[Andrew G]

Seems like a good range of temperatures for some parts of the world . . . Andrew

 

[lustyd]

Could it be you're painting at the wrong time of year? When I last anti fouled the temperature was 20 degrees all day pretty much since it was August. It also had the benefit that my boat was in commission for all but 2 days that year and all year the next year. I've no idea why people insist on painting in the winter when it's horrible out!

 

[vas]

I'm waiting for a 40 degree day to paint my hull...


... been waiting for a few years now.

don't!

I tried it last July in Greece, couldn't use a 100ml pot on a roller! (as LS says, had to throw the pot and the roller within 5mins)
that was undercoat, extremely difficult as they don't allow for more than 10% thinner so spray gun is a nono.
Top coat will be applied next month with hopefully 20-25C only. Wouldn't dare paint with so low temps as humidity will make a mess of the job anyway.

cheers

V

 

[Poignard]

As one who tends never to read instructions until things have gone horribly wrong, may I say how impressed I am that you actually read "what it says on the tin".

 

[Avocet]

I sympathise with the OP. I painted Avocet outdoors and I had to wait for AGES for the right weather window. Couple of words of caution. Firstly, rigging a tent around a boat that isn't on a dry surface (Avocet was in the front garden) can just cause the humidity to rocket, so they don't always work. Secondly, if you DO get bugs in th piant, best thing to do is leave them, do NOT try to pick them off! After it has set you just buff them off (they don't leave very big footprints).

 

[Greenheart]

Thanks for the replies. It hadn't occurred to me that too warm is almost as awkward as too cold. Lusty, I wish your wisdom could follow me around, preventing me foolishly wasting occasional quids on lottery tickets. My daft plan (like many other people's) is not to be painting mid-season! Though I can see it makes sense to.

Avocet, thanks, I reckon I'll forget the tent idea and wait till there's a 72hr dry spell without temperatures falling below about 10°...hopefully this side of Easter. I'm thinking if I apply paint stripper at dusk on day one, hose it off twelve hours later, let the decks dry properly then start painting the following dawn, I can probably count on my calm corner of the dinghy-park to bring temperatures up a bit, enough to kick-start the drying process. On Saturday it was chilly on the beach but pleasantly warm fifty yards inland.