28 BULLETIN 1128, U. S. DEPARTMENT OF AGRICULTURE. 
Salt is of little or no value in preventing blue-stain in comparison 
with the other chemicals. The application of salt after blue-staining 
has well started is almost a waste of money. In fact, the application 
of wet salt or a strong salt solution may prove detrimental in the long 
run, for if the lumber is dried after such treatment the affinity of 
the salt for water may cause the moisture content to remain much 
higher than normal. 
Mercuric chlorid in a 0.1 per cent solution is exceedingly effective 
against blue-stain, but on account of its highly poisonous nature 
and extremely corrosive action when in contact with many metals 
it is little used. 
Shipping green stock closely piled in closed box cars during the 
spring and summer months is almost certain to result in severe stain- 
ing. Indeed, the writer has seen some stock handled in this way 
which stained even in winter. On the other hand, any measures 
taken to prevent staining, such as open piling in gondolas or on 
flat cars, will almost certainly result in severe checking. Of the two 
evils, checking is by far the most serious in airplane stock, since 
checked lumber is greatly reduced in strength, while the stained 
lumber is only somewhat unsightly. Shipping green lumber in the 
close hold of a vessel, particularly if tropical seas are to be traversed, 
is an invitation to swift and sure disaster as far as sap staining is 
concerned. It is doubtful whether dipping in any chemical solu- 
tion now used, except possibly mercuric chlorid, would be effective 
under such severe conditions. 
But, to repeat, the most effective measure to employ against blue- 
stain is speed in drying the wood. Get the logs from the woods to 
the saw with the greatest rapidity and the lumber from the saw di- 
rectly into the dry kiln. 
SAP-STAIN ON SOFTWOODS. 
Certain species are peculiarly susceptible to sap-stain. This is 
due both to the character of the wood and to the climatic conditions 
of the region where the species grows. Western white pine, spruce, 
and southern yellow pine, the last-named wood including longleaf 
pine (Pinus palustris Mill.), shortleaf pine (P. echinata Mill.), and 
loblolly pine (P. taeda Linn.), are very subject to sap-stain, especially 
blue-stain, while true fir and cedar are not so easily affected. Douglas 
fir occupies an intermediate position. 
Besides blue-stain, a red stain has been very commonly found on 
Sitka spruce airplane lumber. It occurred abundantly in the East 
on stock in cars just arrived from the Pacific coast and also developed 
on material along the Atlantic coast which had arrived unstained 
at the port of embarkation but was held over awaiting shipment. 
The stain appeared as terra-cotta or brick-red spots on the rough 
lumber, varying from very faint to a pronounced color. In the stock 
worked up in the factories in this country it was found that the 
stain was superficial, usually surfacing out during remanufacture; 
but reports from abroad indicate that the fungus developed very 
intensively by the time the lumber reached European ports, and the 
discoloration penetrated deeply into the sapwood. The appearance 
of the wood is not marred to the same extent that it is by blue- 
