Some New (To Me) Finishes

[smart dog]

Hi,
Sutherland-Welles polymerized tung oil has always been my go to finish for most projects.  Polymerized means it is heat treated so it dries much faster than raw oil.  It is the tung oil version of Tru-Oil, which is just polymerized linseed oil.  I prefer tung oil because it has good weather resistant properties and finishes by S-W are local Vermont products.  I visit the factory to get my finish.  They have 3 relatively new products that I recently bought, 2 of which I recently used. The first is their basic polymerized tung oil but in a nontoxic solvent called "citrisol". It has the same properties as oil I was using but the solvent is not a petroleum distillate.  It can be thinned with citrisol or mineral spirits and is therefore compatible with the older oil. On my recent musket build I used this oil thinned with turpentine as a sealer. I mopped it on the wood until it would not take any more, wiped off the excess and let dry.  In 4 hours it was dry to the touch but I waited 24 hrs before starting the top coat.  The top coat was S-W polymerized tung oil wiping varnish.  This is simply polymerized tung oil (in citrisol) mixed with polyurethane varnish.  It is very good but it is not a hand rubbing product because it dries too fast. It needs to be applied with a brush, let sit for 10-15 minutes, and then wiped off with a rag. It dries fast and is a really nice finish. Like the polymerized oil, it comes in low, medium, and high gloss. You can apply it to create an in the wood oil finish or build it up for a rubbed back finish. I was very happy with the finish on the musket because I built it up enough to give the finish a slight brittle varnish look like the originals I examined.  The third new product is polymerized tung oil mixed with beeswax.  I have not used this yet but have some future projects that will.  It creates a non toxic low gloss in the wood oil finish that I think will be perfect for the 15th and 16th century guns I want to build.  All of the citrisol based finishes are nontoxic and can be used in salad bowls and other items associated with food.  All S-W products are a bit pricey (averaging about $45 a quart) but they are very good finishes and very weather and wear resistant.

dave         

[Hank*in*WV]

As fast as I would use it, I wonder what kind of a shelf-life it has.

[Eric Kettenburg]

S-W has a good reputation for making good products.  Don't mean to sound annoying but Tru-oil is definitely a bit more than just heat polymerized linseed oil.  Now, maybe their formulation has changed, but it did traditionally made use of a very hefty slug of chemical polymerization agents, most notably codrier or cobalt drier.  No linseed oil product without the addition of chemical drying agents will dry as hard, or as fast, as Tru Oil drys.  Actually, I'd be quite interested to know if S-W is merely heating their tung oil as heating alone is not really a method of effective polymerization unless it is a considerable heat over a period of extended time.  It will drive off residual mucilage, to some degree, and will drive off various water soluble components that may impede drying, but most true polymerization of naturally-derived oils, afaik, is based upon the addition or presence of various chemical siccatives and/or strong UV light.  I would be somewhat surprised if something sold as "polymerized" oil did not include some form of chemical agent to instigate polymerization.

[Eric Kettenburg]

BTW any real chemists around could possibly touch on the issue?  I'd be interested.  Bill Knight and I have discussed this to death but I'm always open to hearing more, more, more!

[smart dog]

Hi Hank,
The shelf life of an unopened can is very long but what usually happens, as you use it up, the seal of the can gets gunked up and air penetrates.  Then the oil gels.  I divide the oil into small jars that are sealed with plastic wrap under the lid.  Eric, why not just call S-W to find what they use to polymerize the oil.  They definitely use heat but they may add some other solvents that further induce drying.  The bottom line is that it does not matter with respect to performance of the finish, which is very good. Moreover, I can make the end result look like anything I desire.

dave

[dogcatcher]

I am a finish junky.  If I see it I have to analyze it, and in some cases I have to try it.  As to this one, yes I have tried it, yes it is a good finish, and a fairly easy and constant product.  But once was enough.  I believe it was or may still be available at Lee Valley. 

After looking at the MSDS sheets on the bottom of this link.  http://www.sutherlandwelles.com/original.html

It appears their formula contains a lot of petroleum distillates, the low luster is 70 to 75%   Other lusters are also contain pd in the 50% range.  http://www.sutherlandwelles.com/pdf/MDS/PTO/MSDSPTOLOW2017.pdf 

The petroleum distillates is a fancy name for paint thinner.  Paint thinner sells for less than $20 a gallon.   It is hard to pay $40 a quart for Sutherland Welles knowing that half of the can is full of paint thinner.   Over the last 40 years I have made quite a few homebrewed finish concoctions, using various combinations of pure tung oil, mineral spirits, and a little Japan Drier.  They may dry a little slower or even faster, but they dry.  I have also used BLO instead of tung oil. 

[smart dog]

Hi Dogcatcher,
You posted the wrong product.  It is listed as botanical tung oil by S-W.  You listed the older petroleum-based product, which is very good.

dave

[dogcatcher]

Hi Dogcatcher,
You posted the wrong product.  It is listed as botanical tung oil by S-W.  You listed the older petroleum-based product, which is very good.

dave

Sorry, I did not catch that in the original post.  But it is DICITRUSOL 65-70% by weight.  A lot of thinner that will evaporate and not be part of the final finish.