Finishing rosewood

philipjdall · 1 Feb 2016

Hello UKW, I've been lurking for a while but now have a question of my own and need some advice...

I've been making a lot of frames in the last few months, mostly from oak and have been finishing them with a very light coat of osmo polyx. They look great and I am very happy with the result.

Light wood frames don't suit all pictures so I recently got my hands on some lovely rosewood. The frame has come out really well and now it is time to finish it...

I tried osmo on a test piece and it has come out rather nicely, so figure I may use this. Is this the norm or not recommended?

Secondly, there are one or two places that need a spot of filler. What can I use don such a dark wood? And then successfully oil?

I just thought I'd ask on here before ruining the piece!

Regards, phil

ED65 · 2 Feb 2016

Not sure if oiling is a good choice for finishing rosewood as it is known to make it go very dark, although that is with linseed oil specifically it might also happen with the Polyx which may contain linseed or a similar oil. I would personally try wiping varnish which can be applied in exactly the same way. You can make your own wiping varnish by thinning a little normal varnish by half with white spirit or turps.

As to filling it, epoxy glue mixed with some sanding dust will work very well with dark woods, and if you use 5-min epoxy the fills should be ready to plane flush in under an hour even in cold weather. You may want to degrease the site of each fill with a quick swipe of acetone or meths, although this isn't always needed some rosewood can be a little oily.

custard · 2 Feb 2016

Hello Philip, I use a fair bit of Rosewood, actually there are many different types each with their own characteristics. But as a broad generalisation, assuming your frames are picture frames or mirror frames, and don't need much in the way of protection, then you'll be just fine with Osmo. Don't worry about darkening, old growth Indian Rosewood is prone to darkening, but you're a lucky man if you've managed to get hold of any of that!

Personally I'd be cautious about mixing sawdust with Epoxy, there's a superficial logic to it, but if you think about it sawdust doesn't have a grain orientation, so you'll be blending up end grain and long grain all together. Consequently sawdust/epoxy tends to look a bit darker when applied as a long grain patch, and a bit lighter when applied as an end grain patch. I'm not ruling it out, but you may well be surprised how effective just clear epoxy can be. Crystal clear epoxy (and it needs to be crystal clear, some like West System Epoxy are a bit yellow) will take it's colour from the underlying wood, so it's a perfect match.

I wouldn't worry about cleaning the timber before applying the patch, but I would be concerned about the mitres with Rosewood and there I would certainly use acetone before assembly. Most Rosewoods are oily, the old growth Indian stuff is often really oily (hence the darkening over time), so a wide frame will need careful underpinning and gluing to prevent it opening up over time as the timber swells and shrinks with the seasons.

Good luck!

philipjdall · 2 Feb 2016

Many thanks for both of your replies!

Custard I am glad you say osmo will be OK. I did a small test and I was quite happy with the result; I had read that on oily woods it sometimes doesn't dry well... But it's gone down well. I have dded a few pics of the wood I'm not sure if you can tell it's variety (I realise diagnosis from photos can be tricky/pointless!).

I have some 5 minute epoxy so I will test with that tonight. Will this take the oil though? I guess I need to test and find out.

I see osmo make a woodfiller that they say you can oil. I can't post the link but it's just called Osmo Woodfiller. I've not bought it - just curious if anyone has any experience with it?

Many thanks again, phil