Acrylic varnish versus Danish oil

[krismusic]

Any thoughts on the above for Exterior hardwood joinery?

 

[Tusses]

read the label

a lot of danish is intended for interior only. I wouldn't be too sure about using the external stuff for anything important either !

dont know what others think ?

 

[krismusic]

I actually not only read the label but also spoke to Rustins. :roll: They recommend their Garden Furniture oil as it has UV filters in it. I was all set to use it until a mate told me that it builds up a yellow colour and stays slightly sticky and so attracts dirt.

 

[Tusses]

it does yellow the wood, as most oils will. as for staying sticky ? if applied and wiped off, and allowed to dry thoroughly between coats then it isn't sticky. also it needs re-applying every 6 months or so.

on dry (1st coat) wood, I mix 50/50 with white spirit to get it to soak in well.

not my 1st choice for outside, but I dont like acrylic either !LO!

 

[Woodfinish Man]

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]

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

I have had good results with microporous. 8) I was told that a clear varnish was not available because of uv breaking down the film. Who makes the Woodshield? Many thanks.

 

[Sgian Dubh]

Who makes the Woodshield? Many thanks.

Sadolin. Slainte.

 

[Woodfinish Man]

Woodshield is made by Smith & Rodger.

Although the clear version does not contain a UV filter (timbers will fade gradually over time) the film will not break down. The microporous product is a flexible coating that allows the timber to expand and contract and unlike a varnish does not leave a thick film over the surface.

WM

 

[krismusic]

Much appreciated. I'll check it out.

 

[Ross]

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

 

[krismusic]

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

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.

 

[Derek Willis.]

Krismusic,
I think if I wre to put a finish on exterior hardwood, I would go for Linseed Oil
as this is one of the most durable of the external finishes, it will of course want re-newing occassionally, and will want a few coats to start.
Derek.

 

[krismusic]

Hmmm. See reservations above. :duno:

 

[Ross]

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]

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

 

[krismusic]

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.

it's a pair of new, Ash French doors. I figure that I should use the same product inside and out, to keep the doors from warping.

 

[krismusic]

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

Thanks for that and the link to a very good web page. You wouldn't go as 21st Century as Acrylic though? The product I am thinking of is http://www.polyvine.com/category/show/product/detail/10

 

[colin taylor]

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.

 

[krismusic]

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.

I am pretty sure that you are right about Sikkens products. I am intrigued by your reference to products that "cost the earth". As it is my own house I may be interested...

 

[colin taylor]

There are 2-pack car clears that probably have to be sprayed, and I don't know if they are flexible enough for wood.
Here's another link to a Jotunproduct that has to have their special primer underneath.
The main way to get a good quality finish to last is to maintain it. i.e. give it another coat every year or so and touching in any bare bits.