TH E H N I C A L NOTE NU MBER 163
PRODUCTS UNIT ROSQQ!%T SERVICE
WIONSIN REVISED JUN 19 9
*gT WL AI N
S U.S. DEPOSITORY
T effectiveness of any wood preserva-tive featent is msed v largely by the depth to which the preservative
pThis can be determined by the followiLg tests, wihrued by the Forest Products Laboratory.
T presence of creosote, creosote mixtures, or other d ored oils is indicated by the dark discoloration, an t of penetration my readily be determined by
i sa e at a point free fro checks and other imperfand at a considerable distance frm the end of the s k is m be done either with an ordinary 1/2-inch
bng the penetration on the wali of the hole, ...n incremnt borer, which brings out a core of wood i sn cross section the depth of penetration and is ained. The observation should be mda at once,
a t oil spreads rapidly over the cut surface, patuoer the end-grain of the wood. With low-viscosity sit is often desirable to exmine a tangential or radial s o the treated wood rather than an end-grain section.
In to peent infection, the hole in the treated piece
sbe tigtly closed with a thorougy treated plug.
No reliable method has been found for determining the d h penetration of pentachlorophenol ehen used in
sor light-colored oil solvents. In boring cores owood recently treated, however, it is often possible to dtg h the "vet" treated portion fro the untreated
As zic chloride is colorless, the depth of penetration othis peervtive ust be ascertained by cheical mean. m c n mthod of determining operation on a cut
f or boring consists in sping ver the freshly cut
sfe a mixture of equal parts of a 1 percent potassium f ic de solution, a 1 percent potsiu iodide solution, an a peent solution of soluble starch. This colors the
UNIVERSITY OF FLORIDA
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treated portion a very dark blue, but does not afec the untreated wood. Although the color fades in tim, it m be brought back by spraying again. This mthod mo be used on chromated zinc chloride.
Sodium fluoride is colorless, but its prene in wood can be determined by the following wthod. Make one solution (1) in the ratio of 5 grams of zirconium wide
in 500 cc of water Make another solution (2) in th ratio of 2 grams of sodium alizarine sulfoate, 40 cc. of concentrated hydrochloric acid, and 460 cc. of uter. Te two solutions are kept separated until ready for ue, when a quantity of solution 2 is added to an equal qu it7 of solution 1. It is essential that 2 be added to 1 rather than vice versa. The cut surfaces or borinp are sprad or dipped in the solution. The treated wood ill tun yellow while the untreated wood will remain dark red. Ths method is also reccmnded by the proprietors of patented fluoride-penol-dichromate preservative to- ure the penetration of the sodium fluoride.
Mbrcuric chloride is also colorless, but dippng the wood in a solution of hydrogen sulfide turns the tted area black.
The penetration of preservatives containing coer
salts, such as Greensalt (Erdalith or Ascu), Celcue, ad Chemonite, can usualy be observed without the ad of a special stain. The following stain has been found us however, for determining the penetration of these pre tives: Dissolve 0.5 grm 5-diphenyl cazbaside in .0 l. of isopropyl alcohol and 50 ml. of water. When a borin or cross section of treated wood is sprayed or dipped in ths solution, the presence of the copper compound is indicated by a purple color while the untreated wood shows little change.
As individual pieces may shov an abormaly hig o
low deree of penetration, a sufficient nubw of tests should be made to obtain a fair e. le shold
be taken at a considerable distance from the ends of the stick, in order that they will not be affected by the longitudinal peneta ion from th. ends. z M 3176 r