UV protecting Varnish - for indoors / Iroko

Tuttlinghorn

Hi, as part of a renovation, the builder is installing wooden reveals* inside some new windows.
The boards are iroko, approx 500 mm wide. They look great, some are quite yellow, freshly cut into planks - some are a lovely light brown. I want to preserve the natural grain, I prefer the light brown colour of the wood, would prefer a matt finish.

The reveals are mostly in south and west facing windows, so I think that I need to get some UV protection onto them ? This is based on me being concerned that the UV will fade and damage the wood over time .. not sure that this is the case though, based on this http://www.hobbithouseinc.com/personal/woodpics/iroko/exposed/index.htm

There will be underfloor heating in one of the rooms and I also want to minimise any VOC / solvents or anything else unpleasant that might be released over the coming years. I plan to exit this place feet first, so hopefully that will be a long while :pac:

I'd appreciate any suggestions on the type of varnish to apply or indeed if varnish is the best approach.

NB - I am working on the assumption that if I oil them, this will mean regular maintenance ? which I'd prefer to avoid if possible!

recipio

Its the type of job you want to do once and then forget ?
I'd use polyurethane which will mature in time and turn the Iroko into a deep chestnut colour.

Tuttlinghorn

recipio wrote: »

Its the type of job you want to do once and then forget ?
I'd use polyurethane which will mature in time and turn the Iroko into a deep chestnut colour.

Thanks Recipio. I don't truly expect to be able to permanently forget it, just don't want an annual maintenance commitment. Does PE imply a glossy finish or is it possible to get Matt?

Since posting above I have also been recommended 'an exterior-grade water-based varnish such as XYZ Quick Dry Outdoor Clear Varnish. This will give minimum colour to the wood. Note our product is only available in gloss and satin, you don't tend to get matt exterior finishes.' This varnish is water-based acrylic ..

Regarding a deep chestnut colour, is this what you mean ? http://www.worktop-express.co.uk/media/gbu0/prodlg/Full_Stave_Iroko_Worktop_lg2.jpg

recipio

I think you might be expecting the impossible. You want to preserve the current brown/yellow colour of the iroko ? I'm afraid all wood tends to mellow with time, especially if exposed to direct sunshine. I actually like the darkening effect of PU - it seems to give a rich patina after a few years as in your sample.
If you want to keep the colour as neutral as possible I believe water based PU will preserve it to some extent. It comes in matt and is 'milky' looking when applied.I have used it on an iroko topped table but found it left a slight 'film' to the finish and didn't penetrate very far into the wood.Alternatively you could explore the new oil/wax finishes like Osmo-Polyx but its a lot of trouble to go to for window reveals. ?

Tuttlinghorn

thanks again Recipio - yes this might be a lot of trouble but they are quite wide and I want to try and get it right - the wood wasn't cheap!

while I've been researching, apparently builder has gone ahead and bought a Sealer to apply before varnish, and is considering Ronseal Yacht Varnish ..?
And when you write that Osmo-Polyx is a lot of trouble, do you mean that its a hassle to apply, or expensive ? or both ..

and yes, i do like the chestnut colour ....... so when i think about it, i guess I do want the wood to change colour a bit ! However what I do not want to end up with, is something very dark (like some older mahogany window boards we had, dark brown..) and no idea how to tell how dark the wood might get ..?

recipio

He has probably bought a sanding sealer ? That will give you a good idea of what a varnish ( almost all PU based nowadays ) will look like.Just to be aware that if its a cellulose based sealer ( as opposed to water or shellac ) you will have to put a PU or alkyd varnish over it.
The secret of getting a good finish with PU is to invest in a good speciality brush and look after it. A good paint shop should advise you on this.

Tuttlinghorn

the sealer was just to go on the side of the board that we won't see. the boards will be installed then we need to choose a varnish for them ..