# Acrylic varnish versus Danish oil



## krismusic (25 Aug 2008)

Any thoughts on the above for Exterior hardwood joinery?


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## Tusses (25 Aug 2008)

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 ?


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## krismusic (25 Aug 2008)

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.


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## Tusses (25 Aug 2008)

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!


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## Woodfinish Man (25 Aug 2008)

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


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## krismusic (25 Aug 2008)

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.
> 
> ...



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.


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## Sgian Dubh (26 Aug 2008)

krismusic":o6iyx7im said:


> Who makes the Woodshield? Many thanks.



Sadolin. Slainte.


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## Woodfinish Man (26 Aug 2008)

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


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## krismusic (26 Aug 2008)

Much appreciated. I'll check it out.


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## Ross (2 Sep 2008)

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


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## krismusic (9 Sep 2008)

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.
> 
> ...


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.


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## Derek Willis. (12 Sep 2008)

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.


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## krismusic (12 Sep 2008)

Hmmm. See reservations above. :duno:


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## Ross (14 Sep 2008)

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.


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## colin taylor (15 Sep 2008)

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


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## krismusic (15 Sep 2008)

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?
> ...



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.


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## krismusic (15 Sep 2008)

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



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


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## colin taylor (15 Sep 2008)

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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## krismusic (15 Sep 2008)

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.



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...


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## colin taylor (16 Sep 2008)

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.


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## Ross (16 Sep 2008)

There are two-part finishes available for timber. Plasticote (or some such spelling) makes a finish that we sometimes use for kitchen worksurfaces that will get a proper soaking. Who knows what it will be like outdoors years from now.

Ditto what Colin says about Polyvine.

Technically, scientifically, I have no idea what UV filters are. The energy of ultraviolet light either has to be reflected, as much of it is in white gloss paint, or absorbed, as much of it is in black paint and clear varnish. If absorbed, the energy is either dissipated harmlessly or it causes damage. I assume that "UV filters" are particles or chemicals added to varnish that will help absorb the energy harmlessly or perhaps even reflect it like tiny mirrors. And my hunch is that they aren't available for all types of finish and aren't particularly effective at the best of times. Pigments or paint solids are good at taking the damage, so paint lasts much longer than varnish. Different resins, natural or man made, will be more or less resistant to damage. 

Old fashioned is not necessarily bad. Plant resins are far better at withstanding ultraviolet light than are complex manufactured polymers. Plant rubber is better than butyl rubber, but butyl is almost indestructible by light compared to polythene. But if you wish to line your pond, your choice is butyl or polythene and not a plant rubber product, it just isn't made. Similarly with wood varnishes, the natural plant products are all but gone and you are left with cheap linseed oil. An expensive alternative is the base oil used in linseed oil paints at www.linseedpaintcompany.co.uk. It will survive a good few years.

The easy option is to use a modern product that is recommended by professional painters who have seen with their own eyes that it works. I can swear that yacht varnish (spirit based polyurethane) manufactured by global industrial paint giants and sold in national diy centres will last beautifully for a whole year. If you are hoping for something that lasts longer, don't trust the manufacturers' word, trust someone who finishes exterior joinery for a living.


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## krismusic (16 Sep 2008)

Hi guys, thanks for the replies. The only thing that seems definite at the moment is a firm no to Polyvine. Both the Jotun and the Linseed seem to offer very good performance but probably quite heavy colour change,


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