Oil finish?

[Munty Scruntfundle]

Hi there.

I have a lump I want to make round today, hopefully I'll have time to finish it. I want to try Danish Oil on this piece, no reason, just experience.

It's what I do before the oil I'm unsure about. I've seen videos where people seal and sand and oil, or just oil. Should I oil, sand, oil?

Just looking for ideas really, let me know what you do, then I can go out and make a mess of it myself!!

Thanks.

 

[Phil Pascoe]

Sand as fine as you wish to go, then wet the work with hot water or steam, allow to dry - it doesn't take long, go for a cup of tea then sand (the finest paper) again. This raises the grain but doesn't stop the absorption of oil like sanding sealer sometimes does. If it does no good it does no harm, unlike causing the patchiness the S/S sometimes does, especially on turned stuff where the grain is all over the place. You can dilute the first coat of D.O. with white spirit, and you'll find if your prep was good you'll need little more than a de nib, and then not necessarily between every coat.

This of course is opinion - others will tell you to use sanding sealer on everything. I personally don't much like the stuff and use it only when I have to.

 

[CHJ]

You should never use sanding sealer before an oil finish, Oil is intended to penetrate the wood to form the bond and bring out the wood grain character and then seal it with a polymerised surface as it cures.

Using a sealer risks the oil forming a polymerised skin that is not fully bonded to the surface and may craze or let go sometime in the future.

 

[woodbloke66]

You should never use sanding sealer before an oil finish, Oil is intended to penetrate the wood to form the bond and bring out the wood grain character and then seal it with a polymerised surface as it cures.

Using a sealer risks the oil forming a polymerised skin that is not fully bonded to the surface and may craze or let go sometime in the future.

I'm no expert on this Chas, but when we were in NZ last year we spent some time with Rick Taylor who does some fabulous stuff using ancient or 'Swamp' Kauri. Whilst there, he made me a beautiful bowl from timber (green and yellow kauri with 'whitebait' streaks) that was 3850 years old. To finish all his bowls and platters, he uses a shellac and linseed oil, which is applied three times using 0000g wire wool to cut back the shine after each application of oil. I asked Rick about this method of finishing and apparently he's been using this method for well over thirty years.
Is what Rick does the same as using a sanding sealer and oil as the OP suggests or something different? I bought his book and can take a pic of the page detailing his finishing method if it's of any interest - Rob

 

[CHJ]

What you are describing Rob, is on a par with the process of French Polishing if I understand the process you describe correctly.

A coat of Cellulose or Acrylic sealer that has added pore fillers in it is a different thing to blending shellac and oil.

I know some folks regularly apply sealer and sand it back before an Oil finish of their choice and have no problems but if someone over coats with sealer without cutting it well back, in worst case applies more than one coat of sealer, it can cause a subsequent finish such as a lacquer or polymerising oil that cures to a harder finish than the fillers in the sealer to fail, there is no guarantee that the finish will not craze or peel some time in the future.

I suspect if you ask a supplier/manufacturer of a polymerising oil finish if it's OK to apply over sealed wood he will not reply in the positive.

Also worth noting that because one user has good result with a particular brand of 'Danish Oil' does not guarantee that another brand of 'Danish' which has become a somewhat a generic term, will behave the same; the individual blend of constituents may well be quite different.


Edit: the Kauri pieces I turned in 2006 were finished with Melamine Lacquer to try and harden the surface.

 

[Munty Scruntfundle]

I've had time and the weather on my side this afternoon so I've turned a small bit of oak, used a little sealer, sanded hard then oiled. And another piece, lighter, I'm not sure what it is, is half done and still on the lathe, this is oil only.

Although they are very different woods (I would imagine oak will absorb slower) one thing is immediately obvious. The grain lines are pulled up much more with oil only. I have a feeling the part without sealer is going to need a good soak a couple more times before I start to get a good lustre, but I'm looking forward to the finish. It also has a suspect crack which I've treated and hope it holds, so it might all turn into a disaster!

Thanks for the feedback, great info.