westerner wrote on Mar 31^st, 2025 at 2:17am:

While I've heard of Japan dryer, I don't really know what it is or how it works. Since you've used it, do you have any detailed info?
On the subject of spar varnish, poly or oil, and why?
Also, do you have a brand preference?
Thanks.

cellargun wrote on Mar 31^st, 2025 at 4:36pm:

 
I use three drops per film roll container of varnish. Not sure how it works either. I used to use Carver Tripp varnish but any will do I'm sure. Had an old can of CT varnish and it was dark and old but it was excellent.

There is a book by Bob Flexner called Understanding Wood Finishing that is very informative. It's not too expensive. My copy is loaned  out at the moment but as I understand it all of these oils we use are some form of varnish and layers of varnish will never melt together like lacquer finishes do. When you put on 30 coats of oil what you have is 30 separate coats of finish and when you rub it out it's damn near impossible not to go through the top coat in places and sometimes cause witness lines or shadow lines. There are some people out there who have done much study and research on understanding the original piano finish on the high  grade guns and as I understand it they think it was put on with a brush in a clean room in one coat. Very interesting subject. The book is worth reading

Japan drier is a chromium salt, that is a catalyst to speed up the polymerization of oil finishes.  I use it also, but don't like to.  It is toxic and/or carcinogenic.  It is essential in making tung oil or linseed oil finishes dry in a reasonable amount of time.  In fact, "boiled" linseed oil is just linseed oil treated with Japan drier or similar.   

The problem I have with most of these finishes is that the bottle dries up after it's opened. More so if you put a rag on the mouth of the container, tip it to saturate the cloth.  So, I dump a few drops into a bowl and use it that way instead.  Still it dries up.  I'm just working on finishing 4 stocks.  I opened an old but full can of tru oil for them.  Yesterday I went to put another coat on, and with maybe an inch out of the can, it is now 85% gelled.  What poured out worked okay still, so I'm continuing to use it.  This was an old can, but all liquid when I started 2 months ago on it.   

I have mixed my own for years, mostly for oil finish on woodworking stuff, but I use the same on gun stocks.

I mix about equal amounts of boiled linseed, spar varnish or varathane, and Watco danish oil to color it.  The danish oil is pretty much a mix of varnish and linseed oil, cut back to 1/3 strength with thinners.  I only use it for the color.  You can color with a different stain instead, and thin the mixture with turpentine or thinner.  When I use the mixture, I pour out a few drops, add a drop of Japan drier, and thin with turpentine.  This mixture is what is sold in stores as wipe on poly.

One thing that I forgot to mention, about my 50/50 linseed oil and spar varnish, is that you should warm the stock, before each application.

Heres a stock I just finished rubbing out yesterday.   

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Was not going to jump into this thread but setting around post shoulder surgery talking to my dogs I changed my mind. So I have a close forty years in the yacht refinishing building business with a side of thirty-five furniture making and doing lots of custom finishing as I got too old for yachts. Before I start just let me say painting and wood finish work is very very subjective. One man’s good finish is another man’s ’ won’t accept ‘. If it makes you happy that’s all that counts. 

Japan Drier: This is basically metallic salts suspended in a vehicle light oil and solvent. The raw metals are dissolved in various acids and special solvents. Do not drink, ingest wash up good. The vats where paint driers are made are always in a well ventilated separate room that smell funny. I worked several month at the Ellis Paint Co. In Long Beach, CA. running  and feeding big pug mills. The primary metallic agents were typically cobalt, manganese, lead years ago and zinc in cheaper paints. Chrome may have been used also but unlikely as it was so expensive and the reason yellows cost more. The last decent brand of Japanese Drier generally available was Gillespie but there are several other better quality driers at artist supply shops.  Jap Drier will darken good spar varnishes but you don’t need much. I use an eye dropper on varnish jobs so two drops to a half cup three to 1.5 cups. I use the old alum measuring cups with a handle. 

Varnish: Include basically resins and oils. The two most common resins are Alkyd a product of polyester and product of different acids, alcohol, fatty acids from linseed, walnut and other nut oils even animal bi-products ( Baker Industries ). Phenolic resins come at a higher cost but are  harder, very strong and durable. Phenol is made  by mixing phenol ( carbolic acid )with
formaldehyde. Alkyd resins are found, in most decent paints while phenolic resin coatings are found in some good spar varnishes and products demanding heat resistance and strength.  Micarta is phenolic resin with laminars of linen. Other resins found in musical instrument making can be made from fossilized tree resins often called Copal Gum Varnish, not to be confused with the cheaper stuff used in construction and other industrial applications. .

After the resin it’s the oils most of which are drying oils. The percentage of oils to resin is proprietary. Varnishes of the spar type are known as long oil so higher % of oil yielding better flexibility for masts, booms and various marine applications. Top grade spar varnish like Epifanes and Petit’s Captain’s Varnish include tung oil while Interlux’s original #90 now called ‘ Original ‘  contains phenol and other oils ? Tung oil varnishes are easily identified by their smell and provided excellent water resistance clarity and amber color. Some other varnishes still use Tung oil such as ProBoat which is Jamestown Distributing brand name. Other common oils are polymerized Linseed oil, and Soya oil. There are still a couple of Norwegian and Dutch varnishes and oil finishes that use fish oils. All of these oils dry at different rates by both oxidation and polymerization. All good varnishes include various additives and a bit of drier to help the user. These additives increase brushing characteristics , flowing Or leveling and UV. Extensive exposure to direct sunlight will create crazing. On boats in Florida it’s usually 12 to sixteenth months while in the PNW many can get years. Much depends on number of coats and direction of sun. Once light crazing is found spar varnish can be sanded back to remove between .005” to .008” and recoated. The better the UV filters the longer it lasts. Good spar varnish has a rich amber color that I believe enhances the wood as much or better than most finishes given it’s ease of use and durability in harsh hot saltwater environments. 

Polyurethane: This product (s)  provide a hard durable tough hide or surface. Can’t recall the pencil hardness number. Generally very aromatic so depending or the job a good mask is best. Somewhat opaque so lacks the clarity through to the the wood substrate that many other products offer.. Minimal to average UV protection even the products advertising UV filters that have been tested found inferior to quality spar varnishes. Sunlight exposure degrades product resulting yellowish appearance then  crazing.  One it breaks down from UV exposure it must be stripped.  Sanding back and recoating is not recommended. Polyurethanes are cheaper priced offer ease of handling and  low viscosity which permits the option of spraying. Life of application depends on amount of sunlight exposure. 

Linseed- Boiled: soaks deeper into wood than any other finish, brings out a nice luster and 
color. Very slow drying as much as a week or more between coats depending on atmospheric conditions and heat. Prolonged UV exposure tends to darken it so it’s never recommended for marine applications. Once thoroughly dry can be over coated with varnish, urethane etc. best applied by brush or hand rubbed where body temperature drives it deeper into the wood. Can be easily blended with other oils such as tung or varnishes to make oil/varnish blend that is easily rubbed leaving non-gloss rubbed effect look very durable easy to maintain. Non Toxic flax seed oil. 

Tung Oil: Most water proof of all oils and leaves a very durable easily maintained non-gloss oiled type finish. It must be hand rubbed on so lots of elbow grease but your hands get it warm and keep it warm and soaking in. Should allow 2-3 days between coats at 60-70°. Then very lightly scuff up or sand with finest ScotchGuard or 300 grit paper, wipe clean apply second coat. Using same routine more coats as needed. For the second coat you can wet sand with 280 or 300 grit using wet-dry paper and Tung oil to lubricate. This will cut a bit of grain and make a wood oil slurry that will fill the grain getting you to a smoother finish faster. Make sure you keep the oil coming by dipping your paper. You don’t want the slurry to stiffen up on you. When done wet sanding take some toweling and wipe off the slurry across the grain until it’s all gone. Come back in a couple hours and you can wipe it all down lightly with the grain like your trying to polish it. If you missed any of the slurry you can re-wet it with some more oil and wipe off.

I  like to add at least another two coats of rubbed Tung oil than let it set a week then varnish after a light 300 or finer grit done dry. One more thing try to soak the butt stock or whatever end grain with a small brush until it won’t soak in anymore this is where your water or cleaning solvent staining originates.   

Epoxy: a 99% solids product so no driers or solvents as it cures by catalyst. Water white no color unless tinted. Very strong in fact a big over kill for gun stocks. Apply by brush and allow to flow. Do not use the ‘fast’ hardener as it can cut down your working window and darkens the resin moderately. In good condition remains flexible. Can be over-coated with varnish after a thorough 220 grit sanding. Clean up requires nasty solvents such as Lacquer thinner, MEK or proprietary citric acid wash.  Does not tolerate UV exposure so once it starts to break down you’re screwed.   

Lacquer: A very high gloss hard product suitable for spraying only. Clears are water white unless tinted. Very fast dry time with working window suitable to spraying only. Surface durability for gunstocks or outdoor surfaces very poor. Chips and cracks upon impact. Can be touched up by an expert since it can be topically blended and rubs outs beautifully. Not recommended

Shellac: One of the original finish products but application is very tricky. Dries very very fast so brushing is advised only on simple small surfaces. Viscosity and color is controllable. Come as white or orange with the later used primarily on darker hardwoods. Mixed with alcohol into different pound cuts ( different subject ). It is however an excellent sealer base coat for those who understand it. It’s pretty much impervious to UV’s, oils, many solvents, and water with the caveat that long exposure to rain can soften it and liquor/alcohol will mar it. It’s kind of a centuries old wonder product that bonds to almost anything and is a great product for patching or protecting your wood if the finish is scraped off. Everybody should have a small acid brush and container of shellac. 

Lastly UV exposure actually plays a minor role with gun stocks as the normally spend little time in direct sunlight and more time in rooms or safes. Water and gun solvents ruin more fine stocks than the sun

Rick 

marlinguy  can wipe on poly be applied to a stock with worn finish with out stripping it?  thanks art