Linseed Oil and Painting

[Big Red]

How long should I wait before painting over oiled timber? The lady at the paint shop said perhaps as long as six weeks! Otherwise the paint might not dry, which would be bad :(

Oh, temperatures at the moment are between 1deg Celcius overnight and about 25deg Celcius during the day. I can't detect any oiliness by touch?

[Wayne Jeffers]

Red,

I'm not sure what you've got, but . . .

Last plywood boat I built, I slathered on the raw linseed oil as long as I could get it to soak into the plywood. A day later, I wiped off any excess. A day or two later, I applied oil based primer. Later, a couple of latex topcoats. No problems.

Assuming you're using oil-based paint over raw linseed oil, your paint should have enough dryer in the mix to ensure any oil near the surface dries and the paint adheres to it.

If you're concerned, you might try your paint in a small test area and see if it dries satisfactorily. Also, depending on the weather at the time you're painting (if not too warm), you can always add a dab of japan drier to your paint to ensure it dries.

If you used boiled linseed oil, it already has driers mixed in so you should be able to paint over it without concern.

Wayne

[Wild Wassa]

BR, what makes an oil based medium special is that it doesn't dry, it oxidises, sets and hardens (these stages overlap). It takes 300 years to dry. If you don't include a solvent it will take even longer.

The lady in the paint shop meant to say, the onset of oxidation, the setting, the hardening and finally the polymerization of the paint will be slowed down considerably.

About the worst scenario, you could face could be about 12 weeks before the paint is hard enough to be usable, and then you would have to have added extra oil to your paint, which of course is ideal, but not practical for most.

Warren.

[ 07-09-2004, 12:35 PM: Message edited by: Wild Wassa ]

[Big Red]

Wayne and Warren,
Its actually for a fence :rolleyes: that I have spent a lotta $$$ on. Its the front fence to my house, so I want it to look schmick.

To me the stuff dried real quick, about 2 days. And it looks a little bit crystaly, maybe even a little like a coat of varnish on the wood. Sorry don't have the vocab' to describe it. The timber didn't soak up very much either.

I thought the six weeks was a bit extreme, so I thought I would ask. It was boiled oild, so I think I will go ahead.

Hey, whats the worst that could happen! ;)

Cheers :D

[Wild Wassa]

A fence? ... that's as cool as. Boats are boring and they are a dime a dozen on this site.

Warren.

[ 07-10-2004, 05:19 AM: Message edited by: Wild Wassa ]

[Big Red]

Aww man, I was embarrassed to say ;) At least its a wooden fence smile.gif

[Bruce Hooke]

As Wayne said, if you have any doubts paint a very small area and see how long the paint takes to get hard. Then check to make sure it is sticking well. If everything is OK on both counts then you should be good to go...

- Bruce

[Alex Batson]

Isn't linseed oil a typical component of paint? If that is the case, how sentive would the paint be to the linseed oil being dry?

[Wild Wassa]

AB, this would be a perfect condition with linseed oil deep in the foundation, one can't use too much binder theoretically, with the heavier concentrations of oil being applied to the top layers (this is called thick over thin or fat over lean). When the paint has polymerised that's the time to proceed theoretically, as the paint has a chance of increased longevity, each layer is somewhat stable. As a painter I don't use the term dry, nor would I want an oil based medium to dry. The moment an oil based medium dries or is depleted of oil, is the time that the medium loses it's flexibility and it will crack (UV also impacts as you know). Part-time painters say dry, painters say polymerise.

Oil seed oils are the binders for an oil based medium historically. Modern oil paint can combine different binders, like an oil and alkyd resin, or an oil and polyurethane blend. Here in Canberra there is only one store that still sells traditional oil paint (not counting artist's materials) dozens of outlets sell plastic oil paint.

Oil based media aren't limited to using (adding) linseed oils, you can use a non-yellowing poppy seed oil or saffron oil, or an oil rich drying medium that comes in different levels of richness. There are many different linseed oils. The price dictates the quality, pale (par) boiled linseed is about $7AU a litre and is the cheapest and the most yellowing, refined linseed is artefact free, cold pressed linseed, triple cold pressed linseed, to name a few of the others that are used. Stand oil is an extremely thick linseed oil and almost unusable for general use as the setting and hardening times are extremely long, but the skin is very flexible.

Warren.

[ 07-11-2004, 02:15 AM: Message edited by: Wild Wassa ]

[Big Red]

Triple-cold-pressed-alkyd-whatsies? Aww. c'mon guys, its only a fence ;) smile.gif :D

[Wild Wassa]

BR, what are you doing back here so soon, I thought you were off painting your fence?

When you said you wanted the fence to look "schmick", I was about to give you a dissertation on why a Mercedes Benz has 17 coats of paint.

Warren

[WindHawk]

My picture site is not working, so I can't show you; but after applying four coats of epoxy on the transom today, my wife convinced me that the RO sander would do a nice job on the cedar porch railings (just the tops).

She's right, of course :rolleyes: ; but, the linseed oil based stain that I put on last year was still fresh enough to lube the paper. It feels good to the touch, but does this stuff ever dry?

I will never again use acrylic based stain (except for year one on green wood... Hey, there's alway's an exception!).

[Bob Smalser]

When in doubt, add a half cup of Japan Drier (paint stores and Home Depot) to your gallon of oil paint.