I was a little prompted to make this video after a correspondence with Karol from PolishedWoodWorking, who had invited me to participate in the European Woodworking collaboration. My tardiness meant I was unable to contribute at that particular occasion, but he spoke to me briefly about a forum of European woodworker who share information, and decipher some of the different terminology used by their counterparts around the world. An example of which is the use by American makers who preference mineral oil, which goes by the name of butcher block oil in the UK.
My research has been based upon primarily the reading of three books: The Artist’s Handbook of Material and Techniques by Ralph Mayer, Finishes & Finishing Techniques from the Essentials of Woodworking Guide, and most interesting a book circa 1940 called Wood Finishes, by H T Davey. In addition were various conversations, programmes and articles which have helped broaden my understanding of finishes.
At the point I stop narrating in the video, I have made mixture of roughly 40/60 Tightbond 3 wood glue and water. I am using different brushes for each finish during this video, so as not to inadvertently contaminate any areas. I apply the primer in a long stroke along the grain.
I then make a small amount of whitening filler and use a heaped tablespoon of the whitening powder, with a chopstick tip of grey rottenstone to which I then add just enough genuine turpentine to form a paste. This was applied against the grain and worked into the wood with an old cloth.
To create the tallow, I then added some raw linseed oil to the remainder of the whitening filler and a small amount of chemical drier. This was again applied against the grain and worked into the wood with a cloth. Please not I am wearing gloves because the chemical drier is quite hazardous.
By this time a thin 20% solution of shellac had dissolved in Isopropyl alcohol and I applied this with a brush. I decided to use Isopropyl because although it is not food safe, it doesn’t contain additives unlike methylated spirit or denatured alcohol, and will therefore fully evaporate. Isopropyl itself is an additive in methylated spirit in France, while other countries use different additives. Please see: http://www.distill.com/specs/EU2.html
The whitening filler was easy to sand down, and clean with Isopropyl alcohol. It left a very smooth finish, however the tallow filler was harder to remove because of its polymerised consistency. The grain fillers were almost invisible after sanding, but the PVA and shellac visibly altered the wood and later their finishes.
The following part of the video includes adding horizontal lines of masking tape, to then apply the finishes as well as labelling all the plastic cups with the names of the oils I will be using. The one thing most people can agree on is that the issue of food safe finishes is a minefield, with a varying range of opinions. As the previous link of actual ingredients in methylated spirit indicates, although the name is the same the constituents can drastically differ.
The red herring in this video comes in the form of a Horse Laxative, which smelt, looked and whose viscosity seemed very similarly to the mineral oil. I applied four coats of each oil finish, leaving about 20-30 minutes between wiping any excess residue, and two hours before the next coat.
Tung oil is the most viscous of the oils and harder to work, but its finish is my favourite. The Raw linseed oil smelt the worse and it’s yellowish colour made the most impact on the finishing surface. Walnut oil was convenient, light but unimpressive. As I mentioned previously, mineral oil and the horse laxative paraffin oil seemed to be identical. It was only a little while ago that horse meat found its way surreptitiously into the national diet, and to think the butchers blocks were being treated with oil also used as a laxative on the same animals, is not only ironic but really emphasises the farcical nature of popular dietary habits.
The other thing to mention is, as I am using veneered birch ply, there is only a small amount of wood for the oils to absorb into before the glue acts as a barrier. In conclusion, it really is a matter of preference, and you can always request Safety Data Sheets from the company you are purchasing the finish from, if you want to know more information.