CA1151358A - Composition and process for coloring and preserving wood - Google Patents

Abstract

COMPOSITION AND PROCESS FOR COLORING
AND PRESERVING WOOD

ABSTRACT OF THE DISCLOSURE
Method and composition for simultaneously coloring and preserving wood by a single application of a contacting solution comprising any one of several known water soluble chemical preservatives containing any or all of the following heavy metals: copper, chromium and zinc, to which pre-servative solution has been added one or more specific naphthalene or benzene derivative compounds having hydroxy, amino or sulfonic acid functional groups attached to a ring carbon atom. Without departing from the teachings of this invention the wood may first be treated with the preservative solution and then contacted with the benzene or naphthalene derivative compound. It is also possible to apply the benzene or naphthalene derivative to the wood initially, followed by the application of the preservative solution.

Description

BACKG~OUND OF T~E INVENTION
This invention relates to a composition and method for both coloring wood to enhance the aesthetic appearance of the grain, and for preserving wood against various destructive organisms or enviromnental agents responsible for rot and decay. More particularly, this invention rclates to a com-position and method whereby the coloring and preservins of the wood may be accomplished simultaneously, in a single application, or sequentially, in two separatc applications which may be pcrformed in either order.
It 31as long been desirable to produce wood products that are artistically and aesthetically acceptable to the public, yet preserved from the destructive agencies of wood.
Wood that is colored and preserved is desirable for the home, and is used in the siding, fencing, and decking industry.
Unfortunately, many of the preservative solutions used to preserve wood from wood destroying organisms impart their own color to the wood. In many cases the coloration imparted by the preserving solution is undesirable for one reason or the other.
One techniquc currently used to color wood is to paint the wood with an oil base paint or pigmented coating.
Depending on the type of æreservative used, some of the coatings will not adhere to the wood, resulting in hlistering or flak1ng in a short period of time. Convcntional petro-leum ~ased preservatives, such as creosote or pentachlorophenol pose problems because of oily films left on the treated .. I

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~ ~S~358 wood, which may rcquire several months to scason, and even , after such scasoning, it still may be difficult for paint or stain to penetrate the oily rcsidue left behind. Water bascd prescrvativcs arc more de.sirai-le than convcntional petrolcwn based yrcservatives becausc thc wood is not coatcd with a film and can be readily paintcd or staincd after ¦treatment. ~owever, coloration is only imparted at the sur-face of the wood with these techniques, rcsulting in limited permanence to weatheriny.
Alternatively, the wood may be prccoated with a coloring agent such as an oil base or latex paint followcd by treatment with the wood prescrvative. ~any of the oil base paints or latex paints will form a coating on the wood which reduces or eliminatcs the penetration of the preservative into the wood. In many cases, thc coatings and prescrv3tivcs are incompatible with onc another.
Many conventional processcs are availablc for coloring and ;taining wood, while scveral r)roccsses arc available to prcserve wood from thc various wood destroying organisms. Yet very ew satisfactory methods are available to color and preserve the wood simultaneous]y. ~he processes that are available are less than desirable because many are multistepped operations. Many conventional processes provide only a surface coloration which will scratch or wcar away and require additional treatment or servicing For exposure to long tcrm wcathcring.
In vicw of thc many shortcolnings ,lpplic~blc lo thc current methods of coloring and prescrving wood, i~ is desirable to havc a process which is not only capablc of colorin-7 and prescrvns the wood by a single ol)cration, but also results in the penetration of the color into thc wood to provide for long term application and stability ~ ~S~L358 ¦ SU~RY OF Tll~ INVENTI~N
It is the object of this invention to provide a composition and method for preserving wood from deterioration by decay and insects, which may alxo simultaneously color the wood in a single applieation.
~ further objcct of this invention is to provide a method of selectively eoloring the wood in sueh a way that the color highlights the grain tones of the wood.
A further objeet of this invention is to provide a method of impregnating the eolor beneath the surfaee of the wood to provide for long term applieation.
Still another objeet to this invention is to pro-vide a method for impartinq eolor to wood whieh results in the api)earallce of uniform eolor on the surface of the wood.
In aeeordanee with the present invention thcre is provided a water soluble preservative solution eontaininc3 any one of several known ehemieal preservative eompositions with ~he proviso that the preservative selected eontain any or all of the following heavy metals: eopper, ehromium, and zine. To this preservative solution is added d speeifie naphthalene or benzene derivative compound having at least one sulfonyl qroup, at least one hydroxyl or amino c3roup, and up to two additional ~roups selected from the group consisting of sulfonyl, hydroxyl and amino, causinq a color to develop in the preservative solution, which, depending upon the speeifie derivative added and the metal ion present in the prescrvative, ean selcctively vary the eolor of thc solution from red to brown.
Naphthalene and benzene derivatives are known in the coloring industry as intermediate compounds useful in ~LS1358 the manufacture of complex organic dyes, However, the use of these compounds in combination with heavy metal wood preservative compositions to impart wood coloring capability directly to the preservative composition, is believed to be a totally new discovery in the art.
The exact mechanism of action which is responsible for the color development which occurs when the preservative composition reacts with the benzene or naphthalene derivative compound, is unknown. Color development may occur through three basic mechanisms:
(1) Formation of a salt between the metal atom and the organic species.

(2) Reaction of the metal with the organic species, for example, oxidation or reduction.

(3) Formation of a complex between the metal atom and the organic species through chelation.
It is believed that the third mechanism is responsible for the color development in this particular system. Copper and chromium belong to a group of elements called the transition metals.
These elements are capable of forming a complex with certain organic compounds containing oxygen, sulfur and nitrogen. Zinc although not a transition metal is capable of forming a complex species with certain organic compounds containing oxygen, sulfur and nitrogen. The chelation mechanism for each compounds and class of compounds will vary depending on the number of organic complexing agents present and also the amount of impurities present. Tnerefore, it is hypotheslzed that when the benzene or naphthalene derivative is allowed to react with the metal containing preservative solution, a complexed metal species or ion is formed imparting color to the mixture. When wood is thereafter treated with this comples preservative mixture or solution according to conventional wood ms/r~r~

'b ~lS~358 treatment cycles employing for example~ either the Full Cell or Empty Cell procQss( both the preservative and the attached color developing ion complex are simultaneously carried beneath the surface of the wood to thereby impart long lasting color to the wood. In this manner the color and preservative are applied simultaneously in a single step operation.
DETAILED DESCRIPTION OF THE INVENTION
Wood is simultaneously colored and preserved by the application of a solution of a known water soluble preservative containing any or all of the following heavy metals: copper, chromium, and zinc, to which solution has been added a benzene or naphthalene derivative compound having hydroxy, amino or sul-fonic acid functional groups attached to a ring carbon atom, in any combination. Each functional group may be attached to any ring carbon atom in any position along the benzene or naphthalene ring, but only one functional group may be attached to any single carbon atom. The salts of these compounds can also be used, and in fact are preferred because of their increased solubility in aqueous systems.
It has been established that benzene based derivatives are operative in the practice of the invention but are not commercially important. Phenol and resorcinol, for example, have inherent water solubility but will yield a weak color complex which will precipitate rapidly out of solution.
It is the naphthalene derivative compounds which are preferred and are the most commercially important. Although a naphthalene derivative will be operative without the preSenQe~
of a sulfonyl group on the ring, it will not have sufficient stability to render the compound commercially useful. 5-Amino-l-ms/l-/3~ ~

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naphthol is an example of one such unstable compound. Therefore, in order for a naphthalene compound to be suitable for commercial use, the compound must have at least one sulfonyl group attached to the ring to render the compound sufficiently soluble in the preservative system. It is preferred that there be at least two sulfonyl groups present to give the composition the desired lony term stability.
Also important to commercial success is the presence of at least one hydroxyl or amino group on the ring, in addition to the sulfonyl group. The presence of the amino or hydroxyl group is essential to intense color development owing to formation of complexes between the benzene or naphthalene derivative and the heavy metal. It is preferred to have two hydroxyl groups, two amino groups or one hydroxyl and one amino group for particularly intense color development.
In summary, the compounds, the salts of which are of particular value in the practice of this invention~ are those naphthalene derivative compounds having at least one sulfonyl group, at least one hydroxyl or amino group, and up to two additional groups selected from the group consisting of sulfonyl, hydroxyl and amino, said groups attached at any position around the naphthalene ring. It is desirable to have three different functional groups attached to the ring; however, it is not necessary to have all three present for good color development.
Examples of napthalene compounds which are particularly suitable for carrying out the method of this invention are.:
1,7-dihydroxynaphthalene-3,6-disulfonic acid; 2-amino-7-hydroxy-naphthalene-5-sulfonic acid; 7-amino-1,3-naphthalene disulfonic acid; 3-amino-2,7-naphthalene disulfonic acid; 1-amino-8~naphthol-2,4-disulfonic acid; 1-amino-2-naphthol-4-sulfonic acid;

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L35a3 2-amino-1-naphthalene sulfonic acid; 8-amino-1-naphthalene sulfonic acidi 6-amino-2-naphthalene sulfonic acid; 1-amino-8-naphthol-4,6-disulfonic acid; 1-naphthylamine-5-sulfonic acid;

4,5-dihydroxy-2,7-naphthalene disulfonic acid; 2,8-dihydroxy-6-naphthalene sulfonic acid; 2,7-diamino-7-naphthalene sulfonic acid;
l-naphthylamine-3,6-disulfonie acid; 8-amino-1-naphthol-3,6-di-sulfonic acid; l-naphthol-5-sulfonic acid; and 1-naphthylamine-8-sulfonic acid.
Examples of water soluble preservative coneentrate systems that can be used with the color complexing agents of this invention are:
~1) Acid Copper Chromate: containing about 28.0% -31.8% copper as eopper oxide and about 63.3% - 68.2% chromium as chromic acid.
(2) Chromated Copper Arsenate (CCA) - Types A, B and C:
TyFe A containing about 16.0% - 20.9% copper oxide, about 59.4% -69.3% chromium as chromic acid and about 14.7% - 19.7% arsenic as arsenic pentoxide; Type B containing about 18.0% - 22.0% copper as copper oxide, about 33.0% - 38.0% chromium as chromic acid about 42.0% - 48.0% arsenic as arsenic pentoxide; and Type C
containing about 17.0% - 21.0% copper as copper oxide, about 44.5% -50.5% chromium as chromic acid and about 30.0% - 38.0% arsenic as arsenic pentoxide.
(3) Fluor-Chrome-Arsenate-Phenol: containing about 20.0% - 24.0% fluoride, about 33.0% - 41.0% chromium as chromic acid, about 22.0% - 28.0% arsenic as arsenic pentoxide and 14.0% -18.0% dinitrolphenol.
(4) Chromated Zinc Chloride: containing about 19.0% -20.0% chromium as chromic acid and about 76.0%- 80.0% zinc as zinc oxide.

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(5) Tanalith*C: containing about 18.9~ copper as copper oxide, about 51.8% chromium as chromic acid, and about 29.3% arsenic as arsenic pentoxide.

(6) Copperized Chromated Zinc Arsenate: containing about 13.0~ copper as copper oxide, about 20.3% chromium as chromic acid, about 11.5~ zinc as zinc oxide and about 25.2%
arsenic as arsenic pentoxide.
All of the chemical compositions and preservatives listed above are commercially available.
In carrying out the method of this invention, the color complexing derivatives of benzene or naphthalene may be prepared as an aqueous solution as a metal salt of sodium, potassium, etc. To increase the solubility of the complexing agent in water, it may be advantageous to increase the pH of the solution to pH 2 to 11 by the addition of a suitable base such as sodium hydroxide, with the preferred pH range between 8 and 10.
The aqueous salt solution is then mixed with the water soluble preservative solution to obtain a final concent-ration of the naphthalene derivative ranging from 0.01% to 2.0% by weight depending upon the concentration of the metal present in the preservative solution. Concentrations above 2.0% may also be used, but due to economic considerations the 2% upper limit is presently preferred. The preferred final concentration of the preservative in solution is about 1% to 2~ by weight, but concentrations ranging from 0.1% to 10.0% may also be employed.

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Temperature`and pressure parameters are not critical to carrying out this invention. A fairly wide temperature range may be employed, with the upper limit at about 150F.
The lower limit should be sufficiently warm to prevent the solution from freezing.
Upon the addition of the salt solution of complexing agent to the preservative solution, the pH of the final solution should be maintained between 0.5-3.0, and preferably between 1.5-2.0, by the addition of acid such as sulfuric, phosphoric, etc.
The color imparted to the wood can be varied from brown to red or some suitable shade therebetween, depending upon the particular combination of naphthalene derivative complexing agents employed, and their concentration. One or more complexing agents may be mixed or blended with the preservative in order to obtain the desired degree of coloration.
The particular metal or combination of metals present in the preservative solution will also influence the final coloration imparted to the wood.
After the complexing agent has been added to the preservative, and a sufficient period of time has elapsed to allow for color development, the wood is treated. Color development usually occurs within 1 to 3 hours, however, depending upon the particular metal or metals present in the preservative and the particular derivative used, the time for color development may be 12 hours or longer.
The treating solution may be applied to the wood by dipping, soaking, spraying, brushing etc. However, ms/ ~

~15~L35b~ 1 vacuum and/or pressure treatment techniqucs arc prefcrred. I
Any known vacuum and/or pressurc tcchniquc may be used to I ~-impregnate the wood according to the method of this invention, ! including both the "Empty Cell~ proccss and thc "Full Cell"
process which are well known to those skillcd in the art.
The "Full Cell", or Bethell, process is employed in the creosoting of railway slccpers and marine timbers and is thc normal method of treatment of any class of timber with water-borne preservatives, and may be used with the treating solution of the invention. It has been in continuous use since 1838 and consists of firit subjecting the timbcr i in a cylinder to a vacuum up to 28 inches for 1/~ to 1 hour, then filling the cylinder with the treating solution and applying a pressure of up to 180-200 lbs. per sguare inch until the required amount of trcating solution has becn injec.ed into the timber. The cylinder is thcn emptied o~
treating solution and the treated timbcr optionally subjected to a short final vacuum to clean up the surface of thc timber. It is usual to heat the treatin~ solution throu(;hout the treatment e.g., to a temperature of 150-200 F, as penetration is better when hot. As in all pressure processes the pressure period is by far the most important factor affecting the amount and depth of impregnation. In practice it is the magnitude and duration of the pressure that governs the absorption of the treating solution by the timbcr. In ¦the early stages of the pre.ssure period thc absorption by the timber is fairly uniform but then it gradually slows down ~ntil the absorption is too slow to bc rcadily observcd.
~lhen this point is reached thc timbcr is :;aid to havc bccn treatcd to r~fusal. The rate of absorption varies greatly i ll -11-~:LS~3s8 with different species, and tlmbers such as beech or Coriscan ¦ pine will be completely impregnated ln a few minutes while I ~.
others likc Douglas fir, larch or oak heartwood are not completely penetrated evcn when under pressure for several days.
The "Empty Cell" treatment, usir~ an initial air pressure, is also known as the Rueping Process and is the , standard method for thc creosoting of transmission poles.
I¦ It is also used for wood paving bloc~s, fen~ing, and ~uil~3ing ¦ timbers, and may be uscd with the treatmcnt solution of the invcntion. The treating ~chedulcs aim at obtainin(3 ccmp~ctc ~, penetration of any sapwood present. The ~uepin~ trcatment was introduced about 1912 and diffcrs from thc full ccll method in that the timber is initially su~jected to compressed air instead of a vacuum. The cylinder is then filled with ¦I the treating solution while maintaining thi~ pr~ssure, and pressure is then increased with a hydraulic pump until the l! desired amount of treating solution is injcctcd into thc ¦! timber. The pressurc is then released and the air compressed ! in the interior of the timber is allowed to escape and in so ¦jdoing expels the c:ccess liquid, leaving the cell walls l~coated with trcating solution. This mcthod of treatment ¦~ allowq a deep impregnation of the timber without a heavy absorption. The compression of the air origin~lly in the wood serves to recover a small amount o~ the injected trcating solution whcn ,he pressurc is relcascd. ~ lon~ final vacuum !is also used to assist in this.
¦ Bcfore impregnating tim~cr with any wood trcatin~
¦solution it is essential to season it first until at least all the frce water has becn removcd from thc cclL spaces.
This stage of seasoning represcnts a moisture contcnt of I .. ~

. j ~ 35~3 ab~ut. 25-30~, varying slightly with different speeies.
There are two very good reasons for this: first, it is not possible to inject another liquid into wood eontaining mueh I water, and second, splits developing as the result of the ¦subsequent drying of thc timher would almo.st ccrtainly expose untreated timber. It is also desirable to carry out all cutting, machining and boring, etc., of thc timber before treatment is applied, as all thcse operations, if earried out after treatmcnt, would exposc untreated wood.
Where these opcrations cannot be done until aftcr treatmcnt all exposed untreatcd timber should be givcn a liheral application of treatinq solution, and holes preferably treated with a pressu.e bolt-hole tr~ater.
It is preferable to color and praservc the wood simultaneously, howcver, in certain instanccs it may be desirable to trcat and color the wood in two stages. t~ithout departing from the teachings of this invention the wood may I first be ~rczted with the prcscrvative solution and then I contactcd with the complexin~l agent. Its i!; a1;so yossibie to apply the complexing agent to the wood initial~y, followec by the application of the preservative solution.
~ iere again, however, it is preferred ~hat the appli-ation process be carried out using any ~nown con~cntional ;vacuum and/or pressure technique.
The following examples will serve to further illustrate the invention.
.1 .
Example I
Southern Yellow Pine, ~measuring 2" x G" x 4') was !I simultaneously colored and preservcd by the Pull Ccll trcatment llusing a l.24a CC~-C solution containing 0.59~ chromic acid, Il 'i Il ,' ~$~

5~358 0.22~ copper oxide and 0.42~ arsenic pcnto ide, and 0~12 4,5-dihydroxy-2,7-naphthalene disulfonic acid. The system was allowcd to react for three hours and the pH maintaincd at 1.8 by the addition of sulfuric acid. The wood was initially placed under a vacuum of 30" Hg for 30 minutes followed by the addition of the treating solution. The system was then pressurized for 30 minutes at a pressurc of ¦ 110 lbs. per square inch. The resulting wood, when dried, was colorcd brown and was also protected against wood dcstroying ! organisms.

xamplc II
~ ouc31~s-fir bloc~s (1-1/2" x 2" x 6") werc simul-taneously colorcd and preserved utilizing the Lowry Fmi~ty Cell process using a 0.8~ CCA-B treating solution containinq 0.28~ chromic acid, 0.14~ copper oxide, 0.3~ arscnic pcntoxide I and 0.63 7-amino-1,3-naphthalene disulfonic acid monosodium 'Isalt. The resultinq wood was air dricd to a 20~, moisturc content and was colored a light bro~. `

Examrlc III
Il To 100 grams of water 0.45 grams of 4,5-dihydroxy-'12,7-naphthalene disulfonic acid and 0.45 grams of 8-amino-1-~'naphthol-3,6-di-;ulfonic acid sodium salt wcre added and the ~pT~ of thc solution raised from 2.7 to 10.0 with ~n3 sodium hydroxide to increase the solubility. Thc intcnsity of color appears to bc in'luenced by t:he ratio of thcse two ~derivatives. While no particular ratio is critical, a mixture ¦lof abotlt 15-70~ of 4,5-cTihydroxy-2,7-nar~thalLne disulfonic acid and ahout 85-303 of 8-amino-1-naphthol-3,6-disulfonic acid sodium salt is particularly effective.

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~lS~358 This solutlon was then added to ~00 grams of a 1.~ preservative solution containinq 0.16~ cllromium as potassium dichromate, 0.17~ copper as copper sulfate and 0.l1% arsenic as arsenic pentoxide dihydrate, and the pH
maintained at 1.8 with sulfuric acid. After 1-1/2 hours of reaction, Western Hemlock was trcated using thc Full Ccll process. The resulting wood was oven dried at 120~ F and was colored a dark brown throughout.

Example IV
l Southern Yellow Pine blocks ~1/2" x 2" x 6") were - ! simultaneously colored and preserved using the Fu]l Cell ¦¦treatment with a solution containinq 2-amino-7-hydroxy-¦naphtllalene-5-sulfonic acid monosodium salt anc~ 4,5-dihydroxy-2,7-napthalcne disulfonic acid disodium salt in a 1.2~ CC~-C
solution.
l Prior to treatment, 0.25 grams of 2-amino-7-hydroxynaphthalene-S-sulfonic acid and 0.25 grams of 4,5-dihydroxy-2,7-naphthalene disulfonic acid werc dissolved in lO0 grams of water. The pH was adjusted to 7.0 with 10~
sodium hydro~ide. Four grams of 50~ CCA-C werc addcd to the solution and the pH adjusted to 1.0 with sulfuric acid. The llmixture was allowed to react for 1-1/2 hours prior to treatment ¦lof the Southern Yellow Pine. The Southern Yellow Pine blocks were placcd in a cylinder and a vacuum of 30" llg l¦applied for 15 minute-;, the treating solution was thcn added !, to the cylinder ar.d the system pressurized to lO0 lbs. per square inch for 30 minutes. The resulting wood, when dricd, was colored a light brown and was also protected agninst wood dcstroylng orqanisms.

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Example V
Southern Yellow Pine blocks werc colored ~ light brown color with a solution containing 1,7-dihy~roxynaph- j thalcne-3,6-disulfonic acid dipotassium salt in a 1.5~ CCA-C
solut:ion using the Full Cell proccss. Initially, 0.5 grams of 1,7-dihydroxynaphthalenc-3,6 disulfonic acid dipot~ssium salt were dissolved in 100 grams of water. After thc dissolution ¦
¦ of the organic complexing a~ent, 3 grams of 50~ CCA-C were ¦ added to thc solution and the plt adjusted to 1.7 with conccntrated ~ sulfuric acid. The solution was allowed to rcact for 2-1~2 ;Ihours and thc pl~ maintaincd at 1.7 with s!lfuric acid prior to t--catment of the Soutllcrn Yellow Pine.
! A variety of woods can be colored and preservcd in ¦accordance with this invention including hard and/or soft !~woods. Any type of wood may be thus simultaneously colorcd ¦and preserved provided it is capable of withstanding conven-tional wood treatment processes.
t~ood colored and preserved according to the mcthod lof this invention resists weathering and has many uses in !' the construction industry. Patio and pool decks, wood siding and beams, fcnce posts, garden ties and poles for outdoor or indoor use are just a few of the possible products ~which may incorporate wood treated according to the mcthod ¦described herein.
,¦ It is to be fully undcrstood that all of tl-c fore-going cxamplcs are intcndcd to be mcrcly illustrativc and ¦not to be construed or interpreted as being rcstrictivc or otherwise limiting of the present invention, exccpting as ¦set forth and defined in the hercto appended claims.

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Claims (41)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A method for treating wood which simultaneously preserves the wood against wood destroying organisms and selectively colors the wood which comprises contacting the wood with an aqueous solution comprising: (a) a water soluble wood preservative containing any or all of the following heavy metals:
copper, chromium, and zinc, and (b) one or more water soluble naphthalene derivatives having at least one sulfonyl group, at least one hydroxyl or amino group, and up to two additional groups selected from the group consisting of sulfonyl, hydroxyl and amino, wherein said groups are attached at any position around the naphthalene ring and the total number of groups is not greater than 4.

2. The method of claim 1 wherein at least two of the groups are sulfonyl groups.

3. The method of claim 1 wherein a salt of said naphthalene derivative is used.

4. The method of claims 1 wherein the final concentration of said preservative is between about 0.1% and 10.0% by weight.

5. The method of claim 4 wherein the final concentration of said naphthalene derivative is between about 0.01% and 2.0% by weight.

6. The method of claim 5 wherein the pH of the aqueous solution is maintained between about 0.5 to 3.0 by the addition of a sufficient quantity of a suitable acid.

7. The method of claim 5 wherein the pH of the aqueous solution is maintained between about 1.5 to 2.0 by the addition of a sufficient quantity of a suitable acid.

8. The method of claim 6 wherein the method imparts a brown color to the wood.

9. The method of claim 6 wherein the method imparts a red color to the wood.

10. The method of claim 6 wherein the water soluble preservative is chromated copper arsenate containing about 17.0%-21.0% copper as copper oxide, about 44.5%-50.5% chromium as chromic acid and about 30.0%-38.0% arsenic as arsenic pentoxide, and the water soluble naphthalene derivative is 4,5-dihydroxy-2,7-naphthalene disulfonic acid.

11. The method of claim 6 wherein the water soluble preservative is chromated copper arsenate containing about 17.0%-21.0% copper as copper oxide, about 44.5%-50.5% chromium as chromic acid and about 30.0%-38.0% arsenic as arsenic pentoxide, and the water soluble naphthalene derivative is 8-amino-1-naphthol-3,6-disulfonic acid sodium salt.

12. The method of claim 6 wherein the naphthalene derivatives comprise a mixture of 4,5-dihydroxy-2,7-naphthalene disulfonic acid and 8-amino-1-naphthol-3,6-disulfonic acid sodium salt and the water soluble preservative is chromated copper arsenate containing about 17.0%-21% copper as copper oxide, about 44.5%-50.5% chromium as chromic acid and about 30.0%-38.0% arsenic as arsenic pentoxide.

13. The method of claim 12 wherein the mixture com-prises about 15-70% of 4,5-dihydroxy-2,7-naphthalene disulfonic acid and about 85-30% of 8-amino-1-naphthol-3,6-disulfonic acid sodium salt.

14. A composition for simultaneously preserving wood against wood destroying organisms and selectively coloring the wood, which comprises an aqueous solution of:
(a) a water soluble wood preservative containing any or all of the following heavy metals: copper, chromium, and zinc, and (b) one or more water soluble naphthalene derivatives having at least one sulfonyl group, at least one hydroxyl or amino group, and up to two additional groups selected from the group consisting of sulfonyl, hydroxyl and amino, wherein said groups are attached at any position around the naphthalene ring and the total number of said groups is not greater than 4.

The composition of claim 14 wherein at least two of the groups are sulfonyl groups.

16. The composition of claim 14 wherein a salt of said naphthalene derivative is used.

17. The composition of claims 14 wherein the final concentration of said preservative is between about 0.1%
and 10.0% by weight.

18. The composition of claim 17 wherein the final concentration of said naphthalene derivative is between about 0.01% and 2.0% by weight.

19. The composition of claim 18 wherein the pH of the aqueous solution is maintained between about 0.5 to 3.0 by the addition of a sufficient quantity of a suitable acid.

kg/

20. The composition of claim 18 wherein the pH of the aqueous solution is maintained between about 1.5 to 2.0 by the addition of a suitable acid.

21. The composition of claim 19 which imparts a red color to the wood.

22. The composition of claim 19 which imparts a brown color to the wood.

23. The composition of claim 19 wherein the water soluble preservative is chromated copper arsenate, containing about 17.0%-21.0% copper as copper oxide, about 44.5%-50.5%
chromium as chromic acid and about 30.0%-38.0% arsenic as arsenic pentoxide, and the water soluble naphthalene derivative is 4,5-dihydroxy-2,7-naphthalene disulfonic acid.

24. The composition of claim 19 wherein the water soluble preservative is chromated copper arsenate, containing about 17.0%-21.0% copper as copper oxide, about 44.5%-50.5%
chromium as chromic acid and about 30.0%-38.0% arsenic as arsenic pentoxide, and the water soluble naphthalene derivative is 8-amino-1-naphthol-3,6-disulfonic acid sodium salt.

25. The composition of claim 19 wherein the naphthalene derivatives comprise a mixture of 4,5-dihydroxy-2,7-naphthalene disulfonic acid and 8-amino-1-naphthol-3,6,disulfonic acid sodium salt and the water soluble preservative is chromated copper arsenate containing about 17.0%-21.0% copper as copper oxide, about 44.5%-50.5% chromium as chromic acid and about 30.0%-38.0% arsensic as arsenic pentoxide.

26. The composition of claim 25 wherein the mixture ms/

comprises about 15-70% of 4,5-dihydroxy-2,7-naphthalene disulfonic acid and about 85-30% of 8-amino-1-naphthol-3, 6-disulfonic acid sodium salt.

27. A method for treating wood which imparts color to the wood and preserves the wood from wood destroying organisms, comprising:
(a) First, contacting the wood surface with an aqueous derivative solution comprising one or more water soluble naphthalene derivatives having at least one sulfonyl group, at least one hydroxyl or amino group, and up to two additional groups selected from the group consisting of sulfonyl, hydroxyl and amino, wherein said groups are attached at any position around the naphthalene ring and the total number of said groups is not greater than 4, and (b) Second, contacting the wood surface with an aqueous preservative solution comprising a water soluble preservative containing any or all of the following heavy metals: copper, chromium and zinc.

28. The method of claim 27 wherein at least two of the groups are sulfonyl groups.

29. The method of claim 27 wherein a salt of said naphthalene derivative is used to make the derivative solution.

30. The method of claims 27 wherein the concentration of the preservative in said preservative solution is between about 0.1% and 10.0% by weight.

31. The method of claim 30 wherein the concentration of the naphthalene derivative in said derivative solution is between about 0.01% and 2.0% by weight.

kg/

32. The method of claim 31 wherein the pH of said derivative solution is maintained between 2.0 and 11Ø

33. A method for treating wood which imparts color to the wood and preserves the wood from wood destroying organisms comprising:
(a) First contacting the wood surface with an aqueous preservative solution of a water soluble preservative containing any or all of the following heavy metals: copper, chromium and zinc, and (b) Second, contacting the wood surface with an aqueous derivative solution of one or more water soluble naphthalene derivatives having at least one sulfonyl group, at least one hydroxyl or amino group, and up to two additional groups selected from the group consisting of sulfonyl, hydroxyl and amino, wherein said groups are attached at any position around the naphthalene ring and the total number of said groups is not greater than 4.

34. The method of claim 33 wherein at least two of the groups are sulfonyl groups.

35. The method of claim 33 wherein a salt of said naphthalene derivative is used to make the derivative solution.

36. The method of claims 33 wherein the concentration of said preservative in the preservative solution is between about 0.1% and 10.0% by weight.

37. The method of claim 36 wherein the concentration of said naphthalene derivative in the derivative solution is between about 0.01% and 2.0% by weight.

38. The method of claim 37 wherein the pH of said derivative solution is maintained between 2.0 and 11Ø

39. The method of claim 6 wherein the aqueous kg/

solution is applied to the wood by a vacuum/pressure process, followed by drying the wood to a moisture content of about 20% or less.

40. The method of claim 6 wherein the aqueous solution is applied to the wood using the Full Cell process.

41. The method of claim 6 wherein the aqueous solution is applied to the wood using the Empty Cell process.

kg/