Re: What should I use for finishing bowls?

I assume you're concerned about applying before the piece is dried?

If so, use the dilute wiping varnishes/Danish oils followed by less dilute with the same resin. Don't think I'd go as long on the oil as the solvent, though. Makes the finish soft.

I have had very good success with Minwax Polyurethane in either gloss or semi-gloss formulas. Sand to 320 or higher, slop on a heavy coat of poly and keep wet for a few minutes. Then wipe it off. Turn the lathe on and burnish it in with a soft cloth. An old T-shirt works great. One or two coats is usually all you need. It's incredibly simple and easy. Try it.

Barry

Hello Derek,

One of the easiest ways to make oil finishes build faster is to seal the wood first, then apply your chosen oil finish. I prefer using thin Lacquer as a primary sealer... For many of the timbers you mentioned, you will see less colour change in the timber if you seal first, the apply the oil.

The thin Lacquer will seal the surface fibres, preventing the subsequent coats of oil from darkening the wood. In addition, the lacquer will allow any oil to build faster, thus saving on material and application costs.

If you prefer not to use a sealer, one of the fastest building oils out there is Liberon Finishing Oil. It is pricy (@ $30.00 per quart), but will build a nice coat much faster than many oils. The cured film is easily buffed and produces a subtle, provocative, sensual feeling when you run your hands over the buffed surface. The cured film also retains a better elasticity than many oils. This can be easily tested by performing a "Thin Film Polymerisation Test" on a glass sheet.

If it's taking you 7-10 coats with your current oil, the Liberon should give the same amount of build in 3-4 coats, unsealed and 2-3 if sealed. This is an estimate though, as I do not know how you are defining an appropriate build level - visual, tactile, gloss, degree of depth etc.

One drawback to using the Liberon FO... It is a medium to darkish amber colour. On light timbers like Pine and Birch, it will cause the surface colour to yellow and darken. This can be eliminated by applying the sealer coat and is what I would recommend. I have been sealing oil based finishes for years and rarely ever apply them anymore without a sealer coat laid on first.

This not only cuts your finishing time down, it also saves a boat load of money on expensive oils. In addition, the sealer will virtually eliminate the colour change imparted by amber coloured oils on light hued timbers. If you do not care for Lacquer, you can achieve the same result with a Shellac based primary sealer. Thin Super Blonde, wax free Shellac would be an excellent choice to consider.

You may also want to consider a water based oil finish. There are only a few out there that I will use at the current state of the development of these oils. If you would like more info on the water based oils, let me know. The water based oils carry their own unique set of preparation challenges, but offer some important benefits for your extra effort. Take care and all the best to you and yours!

P.S. I will let you know when the CD/DVD. Volume 2 is ready to ship and will be happy to offer a combo price with Volume #1.

Hello to the group,

One thing to consider when whipping up a batch of your own oil is that Linseed Oil and Pure Gum Spirits of Turpentine will alter (darken) the colour of your wood over time. Linseed oil has a habit of turning very dark to almost black over long periods of time... Go to any antique store and you will see this on old pieces finished with Linseed oil. Currently, there is no way to chemically reverse the colour degradation caused by Linseed oil.

PGST also will darken over time, to a lesser extent than Linseed. However, be aware of these challenges if you are finishing museum, archival or heirloom pieces. If these challenges are objectionable to you, consider other base oils who do not present such long term problems. Take care and all the best to you and yours!

Why reinvent the wheel - just get some WaterLox and have an easy to use and beautiful finsih that is food safe and durable without the headaches of mixing your own - this stuff is the best!

Ray

I chose Daly's Sea-Fin Teak Oil based on Russ Fairfield's recommendation on

He prefers it to Waterlox.Plus it is available by the gallon in my lumberyard. Maybe the sandingsealer would be the important change from my method currently, to allowfaster build, especially on porous woods.Derek

Ray

Ditto...I "discovered" Waterlox about a year ago...thanks to this group, and absolutely love it.

-- Chuck *#:^) chaz3913(AT)yahoo(DOT)com Anti-spam sig: please remove "NO SPAM" from e-mail address to reply. <

September 11, 2001 - Never Forget

Are you sure this same result would occur with modern boil't linseed oil?

I've heard the argument that the antiques that appear dark may be due to the much dirtier heating systems of old - oil, coal and wood soot becoming embedded in the finish. (I do know that raw linseed oil used outdoors will often host mildew which will turn it very dark- but that's a different situation.)

Hello Owen,

No doubt dirty conditions in days long past contribute to the colour of antiques, but the propensity of Linseed oil to darken is well known in chemistry circles. I know of a few chemists who have spent years trying to find a way to chemically reverse this problem with Linseed oil. No one has ever been able to reverse the colour change without damaging the wood, which is obviously undesirable. Should you find a way, you would no doubt be a very rich man.

Raw Linseed oil is the raw oil that has been packaged without any additives. Boiled Linseed Oils are similar, except the boiled version has been altered through the addition of chemical drying accelerators (solvents and siccatives/driers) and may also include up to 15% Stand Oil, so the colour change would be similar, if not more apparent in the boiled version.

Driers are oil soluble metal salts of organic acids. When these driers are dissolved in aliphatic or aromatic hydrocarbons, they are know as siccatives. When driers are added to drying oils, they are known as "Boiled Oils" Siccatives can also cause colour changes, depending on the specific types used.

Hi Steven,

I use Tried and True polymerized linseed oil which is supposed to have no solvents or driers. I use a UV light booth to accelerate the drying and find that the color change is what I would expect if I left the wood in direct sunlight for a period of time.

Any thoughts on whether or not your experiments with UV inhibitors might prevent the "normal" change I am seeing?

ps - glad to have you back!

George

Hello George,

Thanks for the kind words... :-) Are you referring to the yellowing/darkening of the Linseed oil during the cure cycle?

The yellowing of linseed oil is generally thought to be caused when conjugated unsaturated hydroperoxides are converted into conjugated unsaturated ketones. These unsaturated ketones can produce long-chain coloured polyenes. Additionally, if 1,4 diketones are formed during the drying, enol tautomers can react with trace amounts of atmospheric ammonia. This produces a substituted pyrrole, which can be converted into a coloured product by oxidation, or by condensation in the presence of formic acid.

Coloured metal siccatives also play a role in the discoloration and/or yellowing of linseed oil. To alleviate the yellowing, saturated aliphatic aldehydes may be added to the oil by some manufacturers. The composition of manufactured BLO can vary from manufacturer to manufacturer. The area where the plant grew also plays a part in the specific composition of the base Linseed oil.

My UV inhibitor experiments are centred on the use of Transparent Titanium Dioxide (TTD's) and Hindered Amine Light Stabilisers (HALS), in conjunction with various finishes, including oils. Each of these brings a unique level of protection to the finish, forestalling colour changes and the degradation of the film finish. Since the composition of the base oil can have marked differences, depending on the area in which it grew, I limited the in initial experiments to one manufacturers brand to limit the variables. Using the knowledge gained from that series of experiments, I expanded the test to include commonly available oils.

My testing in this area has spanned several years and has provided a new understanding of the effect of UV on surface films, as well as the ultimate mechanisms of attack from UV on the surface film itself. There are ways to limit, or forestall the degradation of the surface film. There are also measures that can be implemented to reduce the attendant colour changes caused by some film finishes. However, it must be understood that not all colour changes are caused by UV. Other mechanisms can also play a role in colour change, some of these we can exert control over through various measures.

I hope to be able to publish the results of my experiments with UV inhibitors later this year. It may be difficult getting a magazine to publish it though, as to explain the overall problem and the control measures necessary, requires a thorough discussion of the mechanisms of attack, and the measures required to control it. Take care and all the best to you and yours!