26 



HARDWOOD RECORD 



Preparing Logs for Veneer Cutting. 



There are two general methods of treat- 

 ing logs in preparation for veneer cutting, 

 to which might be added that some are 

 worked without any special preparation, 

 that is, worked cold without being either 

 boiled or steamed. The two methods of 

 treatment consist of' steaming and boiling. 

 Both methods of treatment are quite fre- 

 quently used in the same veneer plant, but 

 the boiling method is generally given pref- 

 erence, and steam boxes are often used to 

 help out the boiling vats when they are not 

 of sufficient capacity. There is room for 

 considerable argument on the subject of the 

 relative merits of boiling and steaming. It 

 is claimed by some that steam tends more to 

 crack the blocks open in the end than boil- 

 ing, and that it does not so thoroughly 

 soften the timber. There are some, on the 

 other hand, who claim that boiling has prac- 

 tically the same tendency to split logs open 

 as steaming. Still, as stated above, boiling 

 is generally given trie preference, while 

 steaming is conceded to be the cheapest and 

 easiest to perform. 



There are two methods of constructing 

 steam boxes for logs or blocks, each is, so 

 far as the principle goes, the same process 

 as is used in steaming stave bolts to be cut 

 into slack barrel staves. The old method, 

 and the one most used, is to construct a box 

 of the necessary dimensions, making it as 

 near steam-tight as possible, of course, and 

 then supplying steam, which may be either 

 exhaust or live steam, or both. Generally, 

 when exhaust steam is used, it is supple- 

 mented with live steam. These boxes can 

 be made of various sizes, and should be con- 

 structed somewhat to fit the material to be 

 steamed. A good size is 12x14 feet inside, 

 and high enough so that a man can get in- 

 side and work with convenience. The best 

 box is constructed of cypress with the frame 

 somewhat after the manner of a tank frame 

 so that the joints can be drawn up a little 

 when necessary. The floor should be level 

 with the ground or just a little above it, the 

 bottom, top and three sides should be solid, 

 the front so made that it can be opened and 

 closed, the doors either sliding, swinging or 

 entirely loose, in which case they may be 

 set in place when the steam box is 

 full of material. As more steam escapes 

 through the doors than anywhere else, the 

 steam is generally turned on near the back 

 of the box so that it will work its way 

 through all the material. The time required 

 for steaming in such a box depends largely 

 on the size and nature of the timber, tfut a 

 steaming box is filled up in the evening and 

 by keeping steam in it all night the blocks 

 will be ready to work next morning. In 

 steaming stave bolts the time required is 

 frequently not half this long, but there is 

 quite a difference between steaming stave 

 bolts and round logs, two and three feet in 

 d iameter. 



The other method of steaming has been 

 applied to stave bolts but has not yet been 

 utilized to any great extent in the pre- 

 paration of veneer blocks. It consists in 

 passing the material to be steamed through 

 a tunnel on trucks instead of piling it in a 

 steam box. The operation is somewhat on 

 the principle of a dry kiln. A box tunnel is 

 made of stone, brick or concrete, into which 

 is turned steam, and iron trucks loaded with 

 bolts are let in at one end from the raw 

 material pile, coming out at the other end 

 ready steamed for the stave cutter. This 

 makes it a sort of continuous process and it 

 is quite a favorite method with modern 

 stave manufacturers who cut large quanti- 

 ties of stock, as it eliminates handling the 

 material into the steam box and out again. 

 This same idea might be applied to steaming 

 blocks for making veneer. Of course it 

 would have to be on a more extensive scale 

 than steaming stave bolts, because it takes 

 longer to steam veneer blocks, but the idea 

 holds good and should work in steaming 

 veneer blocks as well as in steaming stave 

 bolts. 



Tanks or vats for use in boiling logs are 

 constructed in several ways. The old method 

 is to build a tank of cypress, making the 

 dimensions to suit the timber and surround- 

 ings, somowhat the same as in making a 

 steam box, and at least partly underground. 

 The depth of these tanks varies somewhat, 

 some of them being only four feet deep so 

 as to take in one layer of large blocks or 

 two of smaller ones. Others are made deep 

 enough to take in two layers of large blocks 

 or three or four of smaller ones, but prob- 

 ably the great majority are only four or 

 four and a half feet in depth, with about 

 two and a half feet underground and one 

 and a half feet projecting above. Regular 

 Bquare tank methods of construction should 

 be followed in building these, and the top is 

 covered with loose boards which can be re- 

 moved in part or entirely for filling or 

 emptying the vat. These vats, like the 

 steam boxes, are generally filled at night and 

 by morning the timber is ready to be 

 worked. The timber is not treated by 

 steam alone but it is practically immersed 

 in water and the steam let into the water 

 may include both exhaust and live steam. 



These tanks are also built of boiler iron, 

 which is much more expensive; but such a 

 tank would stand more rough usage and last 

 longer than a wooden one. Where large 

 quantities of material are to be worked, 

 these tanks are often built of brick, stone or 

 concrete, and cemented inside so as to make 

 them water-tight. 



The problem of deciding on what material 

 to use in constructing either tanks or 

 steam boxes hinges somewhat on local 

 conditions. If the plant is located in 

 the woods in the South, generally speak- 

 ing it is safe to use wood. Cypress, 



of course, is the best material to be 

 had, but pine, oak, poplar and several 

 other woods may be used. Another problem, 

 and one as important in many respects as 

 that of building the boxes or vats them- 

 selves, is their situation. They should be 

 located as conveniently as possible to the 

 veneer cutting machines, so that the road 

 the block has to travel after it is steamed or 

 boiled is short. Boiling vats, where only 

 two or three are required, are usually placed 

 in a row alongside the building with a track 

 between them and the building, so that the 

 drag-saw man can run his truck forward 

 after having cut the log into blocks, and 

 drop the logs directly into the tank or 

 alongside it so that they can be swung in 

 later. A crane derrick is used both for fill- 

 ing and for taking the blocks out of the vat, 

 and the vats should be near enough to the 

 machines for this crane to swing the boiled 

 blocks around and dump them within a few 

 steps of the cutting machine so the skinner 

 can take the bark off and leave the block 

 ready to be swung up by the derrick. Steam 

 boxes do not require a derrick for handling 

 blocks as they are simply rolled in and out 

 of the boxes with a cant hook, but it is just 

 as important to have the steam boxes as con- 

 venient to the cutting machines as the tanks. 

 In some large veneer plants where enor- 

 mous quantities of stock are worked, the 

 method of handling blocks differs somewhat 

 from the ordinary plan. At the big Palmer 

 plant at Poplar Bluff, Mo., for example, 

 where large quantities of gum are cut into 

 slack staves on veneer machines, the system 

 differs entirely from that used at most 

 veneer plants. The tanks are of concrete, 

 and are built in a great cluster divided into 

 compartments of certain sizes, so that there 

 are blocks in preparation and others ready 

 to be taken out continually. These vats are 

 between the veneer plant proper and the log 

 pond, and a dock extends from the vats to 

 the veneer plant on one side and to the top 

 of the log pond bank on the other. The 

 logs are hauled up the slip from the pond by 

 means of an endless chain, where they are 

 immediately cut up with a steam drag-saw 

 into block lengths. These blocks pass on 

 into the tanks at that side, while on the side 

 next to the veneer factory proper there are 

 crews of men continually taking out, peeling 

 blocks and rolling them forward to the 

 veneer machines. 



In locating and constructing either steam 

 boxes or vats, local conditions must always 

 be studied from every standpoint, not only 

 taking into consideration the lay of the 

 ground, but also the capacity of the plant 

 and the material to be produced. Where 

 thin veneer for basket splints and for a 

 number of other purposes is to be made, 

 there is a goodly number of blocks that can 

 be worked without even boiling or steaming. 

 In fact, during the summer months, there are 

 many veneer plants that work more than 

 half their stock without any preparation 

 other than skinning the bark off the block. 



