krismusic
Established Member
Any thoughts on the above for Exterior hardwood joinery?
Woodfinish Man":1l41trzl said:What about a clear microporous product? It doesn't yellow in the same way as an oil and will not build up dirt and grime.
Based on White Spirit the product is deep penetrating but will offer good protection certainly far better than an oil. The one I would recommend is called Woodshield Clear...you will not be dissapointed.
Hope this helps.
WM
krismusic":o6iyx7im said:Who makes the Woodshield? Many thanks.
Hmm! Now I am a bit lost! :lol: The only varnish that I have found that claims to have UV "filters" is the Acrylic. All other manufacturers that I have contacted say that their clear products cannot offer this. Don't want yellowing. I may end up using a clear microporous inside and a colour outside. A bit of a compromise.Ross":3ah16k12 said:I wouldn't use acrylic. Its molecular structure is much larger than old spirit based polyurethane varnishes and so doesn't penetrate the wood very deepily. That's why it doesn't give a darker "wet" look. The result is that it bonds mostly to itself, so when it does break down it tends to come off timber in huge flakes. There are exterior acrylic paints, but varnishes?
No to danish oil for exteriors, especially those that contain wax.
Microporous is the buzz word of the international paint manufacturers today. But ultraviolet light is the main killer of all exterior finishes, not the breathing and movement of timber. It tends to break down the molecular bonds of man-made finishes far quicker than natural oils. Thus "marine" or "yacht" polyurethane varnish on a garden bench will last, oh, a year, or maybe just 12 months before it is in need of refinishing. Linseed oil and tung oil are the traditional oils, but are slow drying and they do yellow. And slow drying does mean sticky (you can thin boiled linseed oil with white spirit and it will dry much faster). But natural plant resins are much more resitant to UV damage than man made resins.
Your choice, really, is yellowing of natural plant oils or UV filters in the varnish. Or why not a coat of one and a coat of the other in a belt-and-braces sort of way?
Ross Samson
Ross":n3o8gn8d said:It might help if we knew what the "exterior joinery" was.
Is it to match something else?
And why the worry about yellowing? When it comes to timber outdoors I haven't heard of people being too choosy about the hue of their finish.
And what timber is it?
If it is oak, the finish is not so important to protect this tough old wood.
If it is pine, the finish is not so important, because it is hard to care that much about the look of pine.
Some wood doesn't react well with some finishes, so, more info, please.
colin taylor":2t3ybm7x said:UV protection depends on pigment in the finish, thus woodstains to a greater or lesser degree slightly obscure the grain. The most transluscent woodstains are probably the Sikkens cetol range, though Sadolin have brought out a new one that looks good.
They are designed for exterior joinery and are a very good quality finish. If you were considering using an oil then you won't mind a light coloured stain like "pine".
Oiled finishes will not last at all in any sun, and any varnish that stands up to UV will be a thick yellow crust that still requires regular maintenance. Old is not necessarily good - come into the 21st century - use the technology available. Decorating Direct
colin taylor":2lari0t8 said:Polyvine grew up with the "paint effects" industry, and did produce some good products. But a clear acrylic is not going to protect the timber from UV. There are some specialised clears that are UV resistant but they cost the earth. Sikkens have been in the exterior joinery business for a long time, and would be a better bet.
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