Although friction polishes are durable and have some advantages over some of the more synthetic finishes like polyurethanes and cyanoacrylates, the latter is typically much more durable over a long period of time. Of course benefits include the comparative ease of application and the ability to refresh the finish by re-application. I use CA, Dr.'s Woodshop, and O.B.'s Shine Juice depending on what I am turning and on how much day-to-day handling I expect the turning to have.
Your Doctor's Woodshop Pens Plus is a variant of the generic friction polish that woodworkers and turners have been using for a long time. They are all a combination of a drying oil (Pens Plus uses walnut oil), shellac (which is almost always carried in methylated spirits or denatured alcohol), and some, but not all have a wax component (Carnauba or Beeswax. Pens Plus uses Cosmolloid 80H which is a mixture of microcrystalline waxes). Most "High Build" friction polishes have a higher shellac content and rarely contain waxes.
In use, the heat from friction drives off the shellac solvent, starts the drying oil polymerization process, and if present softens or melts the wax.
One of the somewhat famous DIY versions is O.B.'s Shine Juice. It is is a friction polish recipe from O.B. (Orelien Burchman) Lacoste from Lafayette, Louisiana. O.B. was one of the founding members of the Bayou Woodturners organization and a friend and mentor to Cap'n Eddie Castelin. O.B.'s Shine Juice has been promoted over the years both on IAP and in several of Cap'n Eddie's outstanding turning videos.
The recipe calls for a mixture of equal parts of Boiled Linseed Oil (BLO), Clear De-Waxed Shellac, and Denatured Alcohol (DNA). Note that although Zinsser's title doesn't reference shellac, Zinsser Bulls-eye Sealcoat Universal Sanding Sealer is a clear, de-waxed shellac. It's what I use in mine.
The instructions, according to Cap'n Eddie, are to use paper towel to apply two good coats of Shine Juice with the lathe off waiting a few minutes between them. Then after another few minutes the lathe is turned on to 500-1000 RPM and a third and final coat is applied. The turning is pinched to create friction so the heat will make the alcohol evaporate, the shellac to begin setting, and the linseed oil to start polymerizing. Cap'n Eddie suggests adding a top coat of wax after the Shine Juice has dried. According to Cap'n Eddie, O.B. would tell us "If it was any easier, I'd have to come over to your house and do it for you".
In January 2022, Cody Walker (Cwalker935), posted here on IAP that he had done some testing on variations of O.B.'s Shine Juice. He tested the original formula of Shellac, BLO, and DNA along with equal parts Lacquer, BLO, & Lacquer Thinner; equal parts Lacquer, Tung Oil, & Lacquer Thinner; two parts Lacquer, one part Tung Oil, & one part Lacquer Thinner; and two parts Lacquer, two parts Tung Oil, & one Part Lacquer Thinner. His conclusion was that the original O.B.'s Shine Juice formula produced the greatest shine but provided a slightly darker finish than the Lacquer formulations. (Probably due to the Boiled Linseed Oil component which is known to darken wood).
So, there you have it, the longest, more verbose answer than anyone could have anticipated. The short version is Pens Plus is a good finish, but it is not as durable in the long term as modern, synthetic, finishes.
Dave
