Best wood primer of old, unpainted dried out external wooden window sills?

[stuart noble]

Which begs the question why this Ronseal stuff, consisting mainly of acetone, comes in a metal container.

[The Natural Philosopher]

Ronseal always comes in tins. Otherwise you wouldn't be able to say 'does what it says on the tin! Simples!

[Lobster]

Thoughts that what he meant - it comes in two parts, of which one is a sachet of catalyst "hardener". Never heard of a wood preservative in two parts.

David

[Ronald Raygun]

He doesn't want filler for trowelling on, he wants a liquid for painting on the wood, and which then sets hard.

I think what he means is some kind of runny resin which, after you've mixed in the catalyst, stays liquid for long enough to soak into the wood before it cures. I guess he thinks one-part hardeners won't go hard enough.

[stuart noble]

I've used a 2 part wood hardener, and it's a hardener, not a preservative. Liquid resin, paste hardener in the plastic cap, not unlike the cans of fibreglass resin from an auto shop.

[Spamlet]

Solvents usually do come in tins. Even if they don't dissolve the polymer itself they still can strip plasticisers, and also polythene is not stable in sunlight. However, this did not stop us selling IPA in 25 litre plastic drums, but acetone is so volatile we would not have done that. I keep 'nail varnish remover' in the fridge but it still evaporates slowly out of the bottle cap. With Ronseal, the main reason for the tin is probably to make sure the solvent has evaporated before you want to use it again... Same goes for the rusty tins of plastic wood and Nitromors and the always split caps of Araldite tubes...

S

[stuart noble]

IMO it's more a question of how long the resin will take to cure when it's applied to a porous surface. Normally you want to get on with the painting without fear of solvent being trapped under the new coating.

If 2 part wood hardeners are no longer available I would use a standard polyester resin, although thin layers can still take a few hours to cure in cool conditions. Low viscosity resins and accelerators are available from GRP suppliers if you want to get serious.

[AL_n]

stuart noble wrote in news:NYrlo.142501 $ [e-mail]:

I trouble with polyester resin, is that the surface remains sticky (i.e., doesn't cure) unless a wax additive is used, and a wax additive will prevent the proper adhesion of any regular paint, as it rises to the surface. I encountered this problem many times when working with GRP. Apart from laboriously removing the wax from the surface prior to painting, the only other solution I recall, was to paint with coloured resin (rather than paint).

Al

[stuart noble]

I've never had a problem with the tack, but I've always used a car body filler on top, which I imagine absorbs any uncured resin

[The Natural Philosopher]

If you mix the resin properly there is no tack.

Gentle heatgun will always fast cure polyester anyway.

Any surplus chemistry can be removed with acetone or similar, but generally not needed.

One wonders how so many fibreglass cars and boats ever get painted if the above were in any way true.

[stuart noble]

AFAIK tack is common to all polyseter resins, hence the wax additive option for the final coat. Nature of the beast

[AL_n]

The Natural Philosopher wrote in news:i77ne1$56l$1 @news.albasani.net:

Only if it happens to be surfacing resin (containing wax).

[The Natural Philosopher]

Ok smartass, what do they put on the surface of fibergalss mouldings that

- isn't tacky

- takes paint

then?

[AL_n]

The Natural Philosopher wrote in news:i77qbu$998$ [e-mail]:

Sorry - I don't share my knowledge with twits who call me smartass.

[The Natural Philosopher]

So, you don't have a clue then?

[stuart noble]

AFAIK you can only get a full cure by excluding air from the surface, so maybe aly foil would work on a flat area, and be easy enough to remove. I imagine the tacky bit must cure eventually, but probably not in a time suited to a production line.

[AL_n]

stuart noble wrote in news:ufNlo.163911$Q_ [e-mail]:

When I worked in GRP (quite a few years ago) we used to use the liquid wax additive and then, once cured, wash the surface wax off with ecetone, and then roughen the surface to provide a key if we needed to apply oil based or water based paint. However, for my window sill job, I guess an easy solution would be to use a coloured resin topcoat (if I can grt hold of a small amount of pigment and not have to buy a large container of it)...

Al

[stuart noble]

I would have thought white spirit could be used, assuming the additive is some kind of mineral wax. If it was soluble in acetone I'm guessing it wouldn't separate out and sit on the surface the way it does.

I once tried diluting a body filler with gelcoat resin to make it more workable, and to give a longer open time. Can't remember what the outcome was, but it should work in theory.

[AL_n]

stuart noble wrote in news:yeZlo.171648 $ [e-mail]:

You've got a point. Perhaps it was white spirit that we used to wash it off. It was a long time ago... Al

[The Natural Philosopher]

I laid up some GF stuff - very roughly using ordinary resin.

I juts sanded it, applied a further coat of resin, sanded that with wet and dry, wiped it with acetone and sprayed car primer on it.

Nothing special, no tackiness, no problem.