This article is from the May 2000 issue, pages 131 - 135.

By Stan Zielinski

Recently I have been trying to repair some Japanese rifle stocks. While it may be easier (and quicker) to simply find a replacement stock, I prefer to keep the original stock with the rifle, particularly if the stock is numbered to the rifle. As I have done wood and metal working (as a hobby) for more than 40 years including considerable rifle stock work, I feel confident in my ability to refurbish rifle stocks. Moreover, replacement stocks are getting harder and harder to find, especially in decent condition at a reasonable price. After making the necessary repairs, I realized the repaired portions would have to be refinished to match the rest of the stock. In so doing I began some research into trying to discover what the original finishes were, since, if possible, I would like to use as close to the original type of finish as possible in restoring these stocks. There seems to be very little factual information on what finishes were used, so hopefully this article can start some investigations into the actual finishes used on the Model 99 rifle stock.

Based on the examples I have seen, it seems that all Japanese rifles used the boiled linseed finish until the introduction of the Model 99.

"Linseed Oil, a yellow, vegetable oil obtained from the seed of the flax plant and used extensively in paints and other protective coatings. ... Raw linseed oil, which has been extracted from the flaxseed but has undergone little or no other treatment, dries rather slowly. The rate of drying may be accelerated by allowing the oil to to stand in air for a long period before application; by blowing air through it; by heating it, either alone or in the presence of certain inorganic substances such as lead oxide; or by dissolving in it certain dryers, generally oil-soluble soaps of lead, manganese, and other metals." ([1],Vol. 11, page 446)

"Flax for seed is grown extensively in the United States and in Argentina, India, and Canada." ([1], Vol. 8, page 49)

The biggest difficulty with the boiled linseed finish is the time it takes to produce a truly water resistant finish. As background, here is the method used by the US in finishing the stocks for the 03 Springfield.

"The oiling of the stock is effected by dipping it into a tank of boiled linseed oil. It is then drained for a few minutes and next placed in a rack to dry for several hours - usually overnight." ([7], page 268)

Anybody who has used boiled linseed oil on a stock will realize that a single such coat will not produce the finish so often seen on '03 Springfields. How was that finish obtained? Here I think is the answer from the official US Army source.

"d. Care of the Rifle Stock. About once a month apply OIL, linseed, raw, with a CLOTH, wiping, to the wood. The surplus oil should be wiped off and the stock polished with a clean dry cloth or the palm of the hand. Care must be exercised not to allow the oil to get into the mechanism of the rifle as it will harden and prevent functioning. The stock and hand guard or barrel guard should be removed from the barrel and receiver for such oiling." ([5], page 104)

The book [7] also contains a reprint of the article "Overhauling the Service Rifle," by Lieut. J. E. McInerny, Ord. Dept., U. S. A., from Army Ordnance, July-August, 1928, Vol. IX, No. 49. On pages 40 - 41 there appears:

"The repairs found necessary on the stocks and handguards are ... and the patching of sections which have been badly cut or bruised. Small cuts and bruises are filled with shellac or a mixture of shellac and sawdust. ... The stocks and handguards which have been accepted after the necessary machining operations have been performed are scraped, sanded and immersed in raw linseed oil and allowed to remain in the oil about five minutes, after which they are removed and allowed to dry."

(As I was finishing this article, I saw the following post on Tuco's Collectors' Forum. "In the mid 50's when I was in the U.S. Army about once a year on a nice afternoon we (platoon) would scrape the old finish from our Garands (w/broken glass), bone the wood to close the grain & reapply linseed oil.This procedure had been done forever & probably accounts for some cases where metal looks better than the wood. It sure removed proofs & cartouches …" It's not unreasonable to assume that other armies also followed similar practices. So that "refinished" stock you see may actually be original and not refinished.)

What I would like to find is the equivalent information in official Japanese Ordnance publications. The reference [3] in Chapter 26 has some additional information on the use of linseed oil, although this usage is more for civilian use.

"Linseed oil has been used for centuries on wood to polish and preserve it but raw linseed oil should never be used in a stock finish as it contains some slow drying vegetable fats which makes for a dull, greasy finish that never really hardens. Boiled linseed oil only should be used, when a linseed oil finish is desired. Boiled oil has never been boiled, though - it is raw oil treated with sulphuric acid or caustic soda which reacts upon the impurities in the oil and allows them to be removed from the oil, which is then heated a little and mixed with a bit of drier. Pure bleached linseed oil has this done and also has most of the natural color removed by activated charcoal. … Watch out for synthetic linseed oil which is not so good for stocks,.." ([3], page 526)

In the meantime, here is some additional information on the materials available to the Japanese for use on rifle stocks.

When the Model 99 rifle was introduced, the Japanese had been fighting in China for two years and increased ordnance production was needed. Why not speed up the rifle production process by using a suitably formulated varnish on the stock and handguard? Production would be speeded up because a more durable finish could be produced in a much shorter time.

When I started to consider this question, my first idea was to look at what varnishes are available. Then I realized I really didn't know what varnish really was. So I spent some time finding the definitions below which were taken from a number of sources, and exclude modern day formulations of varnish and lacquer which are based on various man-made materials. I only want to consider those finishes that were available to the Japanese prior to 1945.

"The word (varnish) has taken on a broad meaning with its years of use. It does not mean any one definite composition, but rather includes many compositions within its meaning. A general definition may state that varnish is any liquid, containing no pigment, which is used for protection and decoration of surfaces, one that can be spread in a thin, homogeneous film and which will dry to a hard, transparent or semi-transparent coating. A chemist would describe varnish something like this, - a liquid which usually is transparent, but sometimes translucent, one which when spread in a thin film on a surface dries by oxidation and by evaporation of its volatile fluid content. It may dry with a high gloss or with a dull lustre. … There are but three major classifications - (1) oil varnishes; (2) spirit varnishes; (3) japans. …Oil or Oleo-resinous Varnishes - These are solutions of gum resins such as amber, Zanzibar, kauri, pontianak, Sierra Leone and gums in fixed oils, usually vegetable oils like linseed and china wood (tung) oil, produced with the aid of heat. They contain small amounts of metallic salts like manganese, red lead, litharge, etc., to facilitate drying, and also volatile liquids like turpentine, mineral spirits, etc., to make the solution sufficiently fluid for brushing. Other vegetable oils like soya bean oil, nut oils, sunflower seed oil, poppy seed oil, and fish or menhaden oil are also used to get certain qualities in special purpose varnishes.

Amber gum is considered the best varnish gum because it is very hard and resists moisture well, but amber gum varnish is dark in color. Zanzibar and kauri gums are the next best because the varnishes made from them are very hard and durable, - kauri is the most used. … It is well to note that varnishes made with a small proportion of oil are harder and more lustrous, but they are less elastic and less durable. Varnishes containing large proportions of oil, called long-oil varnishes, are more elastic and more durable than others, even though they do not take so high a gloss or polish." ([6], pages 153 - 155)

"The long oil varnishes were originally designed for exterior surfaces, and of course durability is the principal requirement for this class. In this group are included the spar varnishes, … Spar varnish is particularly made to resist the action of water and salt, moist air. … A good exterior varnish contains about 36 gallons of oil to 100 pounds of kauri gum." ([6], page 156)

"Spirit Varnishes - These are solutions of gum resins, like damar and lac, in volatile liquids such as turpentine, mineral spirits, alcohol, benzole, etc., produced commonly with and without the application of heat. Shellac is the best known of the spirit varnishes." ([6], page 157)

"Shellac is not an exudation of tree gum as are many of the other resins used for varnish making, although it is collected from trees. It is a resinous incrustation found on certain species of trees in the jungles of India, Ceylon, and other far Eastern countries. … The natural color of shellac is bright orange. … Denaturated alcohol is most commonly used for making shellac varnish by dissolving shellac gum in it. … While shellac is very valuable for many purposes, it is entirely unsuited for others. It will not withstand moisture without turning white. It does not make a really tough and hard surface." ([6], pages 169 - 172)

Given the above, it would seem that shellac would not be a good choice for a gunstock finish. And alcohol, like linseed oil, may have been needed for more important uses. But consider the following passage. Could this explain the colors of some 99 stocks? Perhaps the Japanese substituted some other solvent for the alcohol and added some additional ingredients to improve the water resistance. Any industrial chemists among the readership?

"LAC, resinous substance secreted by the lac insect upon the twigs and young branches of certain trees, the chief of which are species of fig. Lac is a product of southern Asia, particularly northern India. … Females insert their long proboscises into the bark of the twigs or branches, drawing their foodstuffs from the sap. They exude a secretion that accrues and coalesces, forming hard, resinous layers that completely cover their bodies. The ovaries contain a crimson fluid called lac dye, resembling cochineal, which was once used as a dye. Crude lac, known as stick-lac, consists of the resin, the encrusted insects, lac dye, and twigs. When crushed and washed free of the dye, twigs, and insects, it becomes granular and is known as seed-lac or grained lac. After melting and further purification, the resulting lac resin is solidified into thin layers or flakes that constitute commercial shellac. Shellac varies in color from yellow to deep orange." ([4])

"Turpentine, name applied to numerous semifluid, yellow or brownish oleoresins obtained from various coniferous trees in Asia, Europe, and America." ([4])

Could a version of shellac be made from turpentine and commercial shellac? Or perhaps such a finish was tried (producing the characteristic color of some 99 stocks) but then after experience in the humid jungles of south Asia found to be not durable enough. But consider the following:

"Shellac has long been used for stock finishes, usually in partnership with linseed oil. Shellac itself is a waterproofing agent, but it is also subject to checking, cracking, and spotting from temperature changes, since it is not flexible. The French polish employs linseed oil to offset the brittleness of shellac, and allows a high polish, or high gloss stock. It is a fine finish for the gun cabinet, but not so good for the field as water spots it badly and it does not have the quality appearance of a good oil finish. The advantage is that it is very fast - can be completed in 24 hours at most." ([3], pages 527 - 528)

What other material might be used? [3], page 528, which was written in the 1950's, notes: "Varnish finishes are becoming quite popular, and if done properly, compare favorably with the good oil finish. Spar varnishes of the better grades are the only ones to be recommended, for straight finish, but if linseed oil is to be combined with varnish, either spar or good furniture varnish can be used." Now consider the following passage.

"Waterproof Varnishes - China wood (tung) oil has very great water resisting ability. In fact the raw oil is used in China for coating boat bottoms and for many similar purposes where the surface is subjected to water. Therefore the varnishes which are made to resist contact with moisture are often made with a considerable China wood oil content." ([6], page 166)

"Tung oil, a yellow to brown oil obtained by mechanically pressing the sun-dried nuts or seeds of several species of Aleurites, especially A. Fordii, indigenous to China. Because of its superior drying quality as compared with linseed oil, tung oil is extensively used in the manufacture of varnishes, paints, and enamels. It is also used in manufacturing linoleum, India rubber substitutes, and in some insulating and waterproofing materials, and lacquers. .. It is expensive and is frequently adulterated with cottonseed, soya bean, or other oils. ... The plants are native to China and surrounding countries, and scarcity of imports during WWII led to the cultivation of tung oil trees in the southern United States. ([1], Vol. 18, page 277)

"Soybean oil is used chiefly for various food products, including shortening, margarine, mayonnaise, salad oil and cooking oil. Some is used in paint, printing ink, soap, and various other industrial products." ([1], Vol. 17, page 192)

[3], pages 526 - 527, has this to say about tung oil. Note especially possible problems.

"Tung oil is the only other oil I would recommend for stock finishing, and that to a very limited degree. This oil is hard to get and expensive, but it has the advantage of drying about 50% faster than boiled linseed oil. It has two important disadvantages, however. Light applications must be made and rubbed in immediately and thoroughly, as the oil dries fast enough to build up a film on the surface of the wood giving the effect of a plain varnish job, and the oil can flake, check and turn white, just as a poor varnish on the office desk will do."

The problem with substituting tung oil for linseed oil is that tung oil is also used in a number of other ways in a war economy, so tung oil may also have had to been eliminated from usage as a stock finish. What other choices were there? How about lacquer?

"Lacquers are certain natural and synthetic varnishes, particularly those obtained from the sap of the varnish tree, Rhus verniciflua, a Japanese sumac, containing the phenolic resin urushiol." ([4])

"The raw material - urushi, in Japanese, is collected as a milky sap from trees, much as rubber is tapped. The plant is in the family which includes sumac, poison ivy and poision oak, mango and cashew; the raw lacquer is a skin irritant, to which workers must develop a tolerance. After collection, the sap is stirred, heated and filtered, and stored for later use. The lacquer is graded according to the season it was collected, the age of the tree and so forth; different grades of lacquer are appropriate for specific tasks.

Lacquer does not cure in the same way as other natural resins such as shellac, mastic or dammar. Unlike lacquer, these other natural resins are dissolved in a solvent, and when the mixture is applied as a coating, the resin hardens into a solid film as the solvent evaporates. Lacquer, on the other hand, hardens as the result of a complex internal chemical reaction, and, uniquely, does so only in the presence of high humidity. The resulting material is polymerized (like a plastic), and is very hard and durable, and resistant to water, acids, scratches and heat. These properties of lacquer caused it to be used initially as a protective coating - making leather into arrow-proof armor, for example. Lacquerware in good condition has been recovered from archaeological excavations and even underwater sites." ([2])

Note the properties in the last paragraph. Here is a durable water-resistant finish which did not use valuable alcohol, linseed oil, or tung oil and was readily available in Japan. (A coat of this lacquer took about one day to harden, according to the text.)

An interesting comment (which was noted by Thomas Keep in BANZAI, August, 1999, pages 214 - 215) is contained in [3], page 527. "Second and more important, about one man in every thousand is violently allergic to tung oil, and will break out in rash, blisters and even running sores wherever he touches it. Japanese rifle stocks were treated with tung oil, and during the war American soldiers of course captured and handled those rifles. Enough men came down with skin trouble to cause a military investigation, which at first declared the wood itself was the cause, the individual soldiers being allergic to it. It was later found that the stock finish was the cause." Could the finish have been Japanese lacquer and not tung oil? As noted above, many people are allergic to Japanese lacquer, but I have found no other reference to people being allergic to tung oil. Any dermatologists among the readership?

As noted at the beginning, I've probably raised more questions than I've answered. Does anyone have any further insights? Does anyone know of a source of this Japanese lacquer that could be tested on a stripped stock?

Stan Zielinski

21 Kelso Drive

Bow NH 03304-4706

1. The American Peoples Encyclopedia, Grolier Inc., New York, 1964, Library of Congress Catalog Card Number: 64-10465.

2. Bishop Museum (The State Museum of Natural and Cultural History), 1525 Bernice Street, Honolulu, Hawaii 96817-0916, from web site at

http://www.bishop.hawaii.org/bishop/conservation/lacquer.html.

3. Dunlap, Roy F., Gunsmithing, The Stackpole Company, Harrisburg, PA, 1959.

4. Funk and Wagnalls web site at http://www.FunkandWagnalls.com.

5. TM 9-1270, 20 January 1944, U. S. Rifles, Cal. .30, M1903, M1903A1, M1903A3, and M1903A4, reprinted by Normount Armament Co., Box 211, Forest Grove, Oregon, 97116, 1966.

6. Vanderwalker, F. N., Wood Finishing, Drake Publishers Inc., 381 Park Avenue South, New York, New York 10016, ISBN 0-87749-024-4.

7. Manufacture of the Model 1903 Springfield Service Rifle, Wolfe Publishing Co., Inc., P. O. Box 3030, Prescott, Arizona 86302, November 1984, ISBN 0-935632-20-4.