Steel wool

[Inspector]

A WAG but can it be that the surface oil dries quickly and then as the oil deeper in the wood, curing more slowly, releases the solvents or lighter oil compounds to migrate out, softening the surface as it dries? The only other thing I can think of is the resins present in the wood you use may be interfering with the finish. Maybe try a small piece of some other woods to see if they behave any differently. Maple for example. Does another oil finish behave the same?

Pete

 

[Phil Pascoe]

I've found before that sometimes a finish will take an age to dry for no apparent reason - then subsequent coats dry quickly.

 

[Kittyhawk]

A WAG but can it be that the surface oil dries quickly and then as the oil deeper in the wood, curing more slowly, releases the solvents or lighter oil compounds to migrate out, softening the surface as it dries? The only other thing I can think of is the resins present in the wood you use may be interfering with the finish. Maybe try a small piece of some other woods to see if they behave any differently. Maple for example. Does another oil finish behave the same?

Pete

I've had similar thoughts and I believe that you are correct.
Briwax teak oil is in reality a wiping varnish which presumably means its just varnish with an extra dollop of thinners and perhaps some sort of flow agent and can imagine the surface touch drying and then becoming sticky as the solvent dissipates leaving the uncured base behind which hardens over time.
Don't think the Rimu timber is to blame - the timber stocks I have were milled 70 years ago and sands beautifully with no clogging of the sandpaper at all.
I suppose I have to accept this slow curing as a function of the product even though on the can it states the teak oil drying time as 8 hours.

 

[Phil Pascoe]

I asked my b.i.l. (who is head of a school DT department and an ex dockyard (Devonport, England and Devonport, Auckland) ship's joiner) if he'd ever had any problems with rimu. Here's his answer, in case it is of any benefit to anyone else -

Short answer is no. However, there are problems with resinous areas of heart rimu on rare occasions but you can easily spot these. Old rimu tends to get hard and brittle(brash). I think this my be because it does hold on to or have a lot of natural oil/resin retention. That's just my reasoning.
Totara could easily be confused with rimu and you can have real problems with finishes. This stuff is really durable and was used as fence post and exterior joiner. Most of the big Maori carvings were totara. Are you sure it's rimu as it has really variable appearance?

 

[Kittyhawk]

Rimu for sure.
I use Totara when I build a few Inuit style kayak paddles. It's a very straight grained timber, rather soft, light weight and has a purple/ pinkish tinge and unlike Rimu it is a bit difficult to glue.
Totara is quite different