US1602577A

US1602577A - Process of preserving wood

Info

Publication number: US1602577A
Application number: US28501A
Authority: US
Inventors: Herbert D Heckert
Original assignee: Individual
Current assignee: Individual
Priority date: 1925-05-06
Filing date: 1925-05-06
Publication date: 1926-10-12
Anticipated expiration: 1943-10-12

Description

Patented Oct. 12, 1926.

UNITED STATES PATENT OFFICE".

PROCESS OF PRESERVING WOOD.

Io Drawing. Application filed Kay 6,

The present invention relates to thereservation of wood in the form for examp e of poles, piling, railway ties, blocks and yellow pine timber of various kinds "and the object of the invention is toprovide a novel and improved process whereby the penetration of the preservative into the sap wood to the heart wood in the material treated may be effected more thoroughly and with less amount of preservative than has been possible with such processes as have been heretofore used or proposed.

Heretofore it has been proposed to fill the cells of the wood with creosote oil or liquid preservative by submitting the wood directly to the preservative under pressure, but such treatment would be unsuccessful commer-- cially as the high pressure that would be required to effect a thorough penetration of the sap wood of the material treated, or penetration of the preservative to the heart wood would involve the loss of an excessive amount of the preservative because of the highly absorptive properties of the sap wood, and any effort to avoid the loss of an excessive amount of preservative by using a lower pressure would be unsatisfactory as the oil would only partially penetrate the sap wood thus leaving portions thereof untreated or insufficiently treated and hence subject to decay or deterioration, and the relatively low pressure of the preservative in the presence of the highly absorptive properties of the sap wood would be insuflicient to insure penetration of the oilto the heart wood. In other processes, heretofore used or proposed, the preservative oil injected into the wood has been permitted to remain therein for the purpose of filling the cells thereof, but such a procedure involved the consumption or loss of an excessive amounts of oil or preservative.

The present invention provides aprocess whereby thorough enetration of the preservative oil throug out the sap wood 15 attained without excessive absorption of oil or preservative, so that the sap wood Wlll be thoroughly preserved by the use of a minimum amount of oil and the avoidance of excessive absorption of the preservative oil in the sap wood enables a sufiiciently high oil pressure to be applied to the wood to 1nsure penetration of the oil to the heart wood. Moreover, the process provided'by the present invention enables a substantial amount of the preservative oil employed to treating wood for the 1925. Serial No. 28,501.

so that the oil thus'recove'red may beused in a subsequent treatment of the wood which may be effected inorder, to seal the cells of the wood and thus prevent loss of the preservative oil injected by the previous treatment, by leaching or evaporation.

The procedure preferably followed in reservation thereof by the process provide by the present invention, which may be carried out with the aid of apparatus such as that commonly usedin the creosoting of wood as heretofore practiced, is substantially as follows: The charge of wood in the form of poles, piling,"ties, blocks or timber is placed in a chamber such for example as the cylinder commonly used in the creosoting of wood by other processes, and the Wood is seasoned or dried, preferably by steaming in the cylinder, followed by the application of a vacuum pressure within the cylinder as is usually performed as a preliminary step in the creosoting of wood by other well known processes. This preliminary treatment, or any equivalent thereof, is for the purpose of drying the wood as thoroughly as ossible and thus preparing the wood to ta e up the preservative oil freely and to facilitate the penetration of the oil through the sap wood.

After the wood has been thus treated in the cylinder, it is subjected to the action of an atmosphere of a gaseous medium produced for example by forcing air into the cylinder until it reaches a pressure of from 40' to pounds per square inch, and while the wood is maintained under the influence of this compressed air, or without releasing the air pressure, the cylinder containing the charge of Wood under treatment is pumped full of creosoteoil such as that commonly used in other well known creosoting processes, or any other suitable preservative in liquid form, until the creosote oil or preservative reaches a'pressure preferably of at least 150 pounds per square inch. The

charge of wood is maintained under the penetrating influence of the creosote oil or preservative which submerges 1t substantially at the pressure thereof as stated, un-

til about 80 per cent of the total amount of creosote oil which the wood is to receive has, penetrated the wood, this being for example calculated according to the cubic feet of wood composing the charge undertreatment, and the drop in the level of the oil in the treating tank due to the penetration of the oil into the wood, as indicated by a gauge which may be provided on the treat- 1ng tank. Creosote oil is preferably used as the preservative, and it is introduced into the treatin cylinder at a temperature preferably of a out 190 to 200 F.

After the wood has received the desired amount of creosote oil or preservative under the treatment described, the creosote oil is drawn off from the cylinder when it may be suitably stored for subsequent use, and a vacuum of about 15 inches of mercury is created within the cylinder containing the wood under treatment. The purpose and effect of this vacuum treatment is to remove all excess air from the Wood, and which if present would resist or impede the subsequent injection of creosote oil, to be presently described, and to remove with the air any surplus oil or preservative, this vacuum treatment of the wood being continued for a period preferably of at least 20 minutes. Upon completion of the vacuum treat ment, the treating cylinder containing the wood under treatment .is again filled with creosote oil, preferably at a temperature of 190 to 200 F. and pressure is applied to the oil until it reaches a pressure preferably of at least 110 lbs. per square inch, and this pressure is maintained until a gauge readmg of the treating tank shows that the wood under treatment in the cylinder and which is submerged in the body of'creosote oil therein has absorbed the remaining proportion of the total amount or charge of oil which it was intended the wood should receive, which would be 20 per cent of the total charge when 80 per cent of the total charge was absorbed by the first treatment described above, allowing for the amount of oil which is absorbed b the wood while the cylinder is being fille with oil. The purposes and effects of this second or subsequent oil injection are to refill the cells of the wood which were emptied of oil and air by the vacuum treatment following the first oil injection, to seal the cells and thus exclude moisture, fungi and germs which mightcause decay of the wood, and to prevent the loss of the creosote or preservative oil by leaching or evaporation.

By submitting the wood to an atmosphere of a gaseous medium such as compressed air, and applying the oil under pressure without releasing the pressure on the air or gaseous medium, the minute cells or crevices of the sa wood on the poles, ties, blocks or other odies of wood under treatment become filled with such air or gaseous medium and hence the highly absorptive properties of the sap wood are counteracted to a substantial degree, so that the oil may be subjected to a high pressure which will insure its penetration throughout thesap wood without excessive loss of oil due to the highly absorptive pro rties of the sap wood and the use of a hig pressure on the oil which thus made possible enables the oil to reach into and penetrate to the heart wood. Penetration of the preservative orig throughout the sapwood and to the hea wood is thus attained by the use of a minimum amount of oil or preservative, as the loss of oil due to the highly absorptive properties of the sap wood is reduced to a minimum byreason of the presence of the air therein atthe time the preservative oil is injected. g

The vacuum treatment which follows the first oil injection removes any air remaining in the wood and it also removes from the wood any surplus or unabsorbed oil which will be carried or forced out of the wood with or in advance of the escaping air, this further economizing the amount of oil used.

-The subsequent or final injection of the cresote oil or liquid preservative may be accomplished at a pressure less than that employed during the preceding oil injection, as its purpose is to fill the cells of the wood whichwere emptied by the vacuum treatment following the first oil injection, thus protecting the wood a-gainst the entrance of moisture, fungi, germs or other destructive media, and thecells are sealed so that loss of oil by evaporation or leaching is minimized or prevented.

The wood preserving process provided by the present invention enables poles, iling, ties, blocks and other pieces of woo comprising more or less sap wood to be thoroughly treated with creosote oil or other liquid preservative with the use of a mini- .mum amount of oil or preservative, the

highly absor tive sap wood being 1prevented, by the air ling it during the rst treatment, from taking up an excessive amount of the oil or preservative, so that a sufficiently high pressure may be applied to the preservative oil to insure its penetration into and throughout the sap wood and to the heart wood.

' I claim 1. The process of preservin wood which comprises submitting the woo to a gaseous atmosphere at a pressure above atmospheric pressure, submitting the wood to the action of a li uid preservative at a pressure substantial above that of the gaseous atmosphere, t ereby coating the walls of the interior cells of the Wood with the reservative, removing the gaseous atmosp ere and surplus preservative from the cells of the wood, and then submitting the wood to a liquid preservative at a pressure substantially above atmospheric pressure to seal the cells of the wood.

2. The process of preserving wood which comprises submitting the wood to compressed air at a-pressure substantially above atmospheric pressure, submitting the wood to the action of a liquid preservative at a pressure substantially above that of the compressed air thereby-coating the walls of the interior cells of the wood with thevpreservative, submitting the wood to a vacuum pressure, and then submitting the wood to a liquid preservative at a pressure less than that at which the first plied to seal the cells 0 the wood.

3. The process of preserving wood which comprises submitting the'wood to an atmosphere of compressed air at a pressure substantially above atmospheric pressure, submerging the wood in a liquid preservative at a pressure. substantially above that of the atmosphere of compressed air, maintaining such pressure on the liquid preservative until a predetetermined proportion of the total amount of preservative to be taken up by the wood has been absorbed thereby, then submitting the wood to a vacuum pressure at a sufiicient pressure and for a sufreservative was apfioient period of time to remove air and surplus preservative from the wood, and then submerging the wood to a liquid preservative at a sufiicientpressure and for a sufficient period of time to cause the wood to take up the remaining proportion of the total amount of preservatlve.

4. The process of preserving wood which comprises submitting the wood to compressed air at a pressure of at least 40 pounds per square inch, then submitting the wood, without releasing such compressed air pressure to a liquid preservative at a ressure of at least 150 ounds per square inch until a predetermined proportion of the total amount of the preservative to be taken up'by the wood has penetrated the same, then submitting the wood to a vacuum ressurewf about 15 inches of mercury r a period of at least 20 minutesyand then submitting the wood to a liquid preservative at a pressure of at least 110 pounds per uare inch until the remaining proportion o the total amount of the preservative to be taken up by the wood has penetrated the same.

' HERBERT D. HECKERT.