Varnish not drying

[Colin]

I recently varnished a sign (indoors) with some international yacht varnish.

2 days later the varnish is still tacky. The pot says that the varnish should be dry within 4 hours. The wood is an old kitchen door (American Oak). I did not strip the original coat of varnish, just sanded it down to provide a key.

Any ideas why the drying time is soo long?

I have noticed this problem in the past with other projects, where the first coat always seems to take longer...

Any way of speeding up the drying?

TIA Colin

[Lobster]

Presumably you stirred it thoroughly before starting?

David

[Mike Halmarack]

I had a similar problem when using some varnish I'd bought from B&Q. I'd painstakingly stripped a framed and many paneled bureau with paint stripper and various scrapers. After washing, drying and rubbing over with wire wool, I applied the varnish. A month later it was still slightly tacky to the touch. I was quite miffed to get this result after all the work I'd put in. I covered it with a dust sheet for a couple of months more , after which it became serviceable. I don't know what the cause was. I wanted to blame B&Q but never became sufficiently convinced.

[Rosie]

I did this - painted a table with yacht varnish and it never dried. I was told that proper yacht varnish doesn't dry properly, so that the deck of the boat doesn't get slippy. I've no idea whether that was true. I ended up stripping it and starting again with a proper interior varnish.

ROSIE

[stuart noble]

Probably "trapped" solvents. If too much is applied in one coat, the surface dries prematurely and stops the solvents evaporating from the rest of the film.

[Colin]

Nearly dry... I'll give it another few days...

Colin

[Paul Mc Cann]

Sometimes wiping over with appropriate thinners will cure this problem.

[N. Thornton]

just give it a week or 2, and use more suitable varnish next time.

[Jan Wysocki]

Ultraviolet light will accelerate the 'drying' (really polmerisation) of varnish. Sunlight is a free source of ultraviolet, but it's absorbed by glass.

[Colin]

Not much chance of sunlight here over the next few days :-)

Thanks for the tip.

Colin

[Roland Mann]

No, yacht varnish should always dry properly. The main reasons why varnish doesn't dry are:

- Failing to stir it properly

- applying it too thick - varnish needs lots of thin layers and time to dry in between

- applying it over an incompatible substrate - a previous coating that it reacts to

- wrong temperature - too cold or too hot. Too hot sets the skin too quickly and slows down evaporation of the solvent

- too much humidity (which sometimes causes a white bloom to appear)

Roland Mann Jenny Painting Systems

[P.R.Brady]

Don't want to depress you but we have some stairs with varnish which has not dried fully and we've waited a year. Vim taking it back to bare wood was the remedy. We found the tin in the shed with the lid off - the surface of the varnish had not even skinned. I suspect a bad batch or, more likely, the previous owner contaminated the tin with cooking oil or something! Phil

[N. Thornton]

diffused skylight contains just as much UV. Glass windows block it though.

NT

[Pete C]

I've never had much luck sunbathing under a parasol, let alone sunbathing on a cloudy day :)))

cheers, Pete.

[N. Thornton]

uv photosensitive pcb works fine on cloudy days. NO suntan doesnt mean no uv, just means not as much as in summer.

NT

[Andy Dingley]

Spar varnish (the real stuff anyway, which most isn't) is intended to remain flexible in service. It does "dry", but dry isn't especially hard and it's much less than glossy.