O'Neil, W. J. (William James)

University of Missouri: MOspace

Fig. 1. Equipment needed for treating posts by the hot bath-cold bath creosote method. Report on Department of Forestry research p,roject Number 120, entitled "Timber Crop. ' Tests On Treated Fence Posts W.J. O'Neil What native tree species yield fence posts that are most serviceable for farmers under Missouri condi-tions? What kind of preservative treatment, other than pressure, is most effective in lengthening the life of non-durable fence posts? What equi pment does a farmer need for treating his own fence posts? In 1938 the Department of Horticulture and Forestry in co-operation with the Department of Agricultural Engi-neering initiated a simple experiment to obtain ans-wers to these questions. . It is estimated that over 7,500,000 fence posts are used annually in the state of Missouri. During the peak year, 1946, over 20,000,000 posts were utilized. Approximately 80 percent of posts used each year are replacements for posts rendered unfit for further ser-vice by insect and fungous attack. The rest of the posts are used for new fencing, which eventually will re-quire replacements. A well constructed fence has a life expectancy of25 years if made out of durable posts. Untreated posts of non-resistant heartwood often rot out in 3 to 5 years. If these non-durable posts can have their life extended by an inexpensive preservative treatment so that they last over 20 years, farmers can realize a considerable saving in time and money. EXPERIMENTAL PROCEDURE Selection and Preparation of Posts. The twelve species selected for study were basswood (TiNa ameri-cana 1.), catalpa (Catalpaspeciosa Ward.), eastern red-cedar Uuniperus virginiana 1.), American elm (Ulmus americana 1.), slippery elm (Ulmus rubra Muhl.), hackberry (Celtis occidentalis (1.), shagl:>ark hickory ( Carya ovata (K.) Koch), black locust (Kobinia pseudO-acacia 1.), black oak (Quercus velutina Lamarck), chin-kapin oak (Quercus muehlenbergii Engelm), white oak (Quercus alba (1.), and shortleaf pine (Pin.us echinata MIlL). All of these species are common to Missouri. The fence posts were cut during the period of October, 1936, to May, 1937, and were stored on the second floor of the Agricultural Engineering labora-tory for seasoning. Posts were of two types, split and round. The slippery elm posts were split, while the posts of cedar, basswood, black oak, and hackberry were a mixture of split and round posts. Posts of all the other species were round. The posts were cut 6.5 feet long. They were mea-sured carefully and the following data recorded: butt diameter in inches, top diameter in inches, number of annual rings in the last inch, and total number of annual rings. The size of the posts varied. The average butt diameter ranged from 5.9 inches to 4.1 inches with a maximum diameter of 7.7 inches and a mini-mum diameter of 3.3 inches. The average top diameter varied from 5.1 inches to 2.9 inches with a maximum diameter of 6.5 inches and a minimum diameter of 2.2 inches. Types of Preservative Treatment. Most of the commonly known treatments which did not involve the use of pressure or expensive equipment were tested in this study. Since the experiment was initiated, sever-al new preservatives have come on the market. Penta-chlorophenol is one of the better of these new pre-servatives. Because the hot- and cold-creosote bath treatment can be given readily with the equipment most farmers possess, eight posts of each of the eleven species re-ceived a hot bath of creosote at a temperature of 220°F, followed by a cold bath of creosote at air temperature (Fig. 1). The posts were left in the hot bath for 2114 hours, after which they were placed in the cold bath for one hour. Catalpa posts were not treated. Fourteen other treatments were applied to black oak and basswood posts. These 14 treatments involved a total of 71 posts of each of these species. The number of posts in the individual treatments varied from three to six. A large number of posts were used to test more fully the most promising preservatives and methods on a relatively soft hardwood, such as basswood, and a relatively hard hardwood, such as black oak. Eight different hot- and cold-bath creosote treat-ments were applied to two or three feet of the butt end of black oak and basswood posts. Treatments varied in the length of time that the posts were left in both the hot and cold bath. After treatment the posts were al-lowed to drain for 24 hours by placing them across two parallel timbers so that the posts were elevated above the ground. Fig.2. Treating posts with zinc chloride by the tire tube method. (Photo by U. S. Forest Service.) Theother six treatments employed were: (1) painting the posts with hot creosote; (2) painting the p stswithhotcarbolineum; (3) soaking the entire post in crankcase oi l for one week; (4) soaklng the entire post in a 5 percent solution f zin chloride for neweek; (5) u ing zinc chloride by the tire-tube method· and (6) using cwo proprietary products, o molit and Osmoplastic. The tire-tube method nsist of laying unpeeled green posts on an inclined stand or platf, rm with th butt end elevated (Fig. 2). Th butt end is then sm othed, and grease is applied s that the tire tube fits tightly around the po t. A zinc chloride solution equivalent to a 5 percent solution (made by mixing 21 p unds of a 50 percent zinc chloride lution in lO gaJl n of water) is p ured into each inner tube. Tbe s lution is then carned by the force of gravity toward the small end of the post. Th exces olution can be reclaimed as it drips out f the end f the post. In u ing the 0 molit process fresh ly cut p sts must be p eled of aU outer and inner bark. Osmoli t is mixed with an equal part of water, by weight, and is then brushed over the entire outer surface of the post. The pOSts also may be dipped into the solution. In this experiment th e pOSts were painted. When the posts are thoroughly covered with the solution, they are piled in a pyramid and overed with hay, straw, or si milar material to prevent rai n from washing off the solution and to slow up the seasoning of the POSt. The posts must remain covered for 3 ro 4 weeks. In the Osmoplastic treatment, the bark is re-moved for a distance of 4 inches above and 8 inches below what will be the ground line when the post is set for use in a fence line. The solu tion is brushed n the surface of the p st. If the treated area is covered w ith a waterproofba ndage, the treated post may be s t immediately ; cherwise, the posts should be sea-soned for two w ks bd re being et. In this study the water-proof bandages were used. Settingof Posts and Subsequent Examina-tions. A total of 322 posts fr m 12 different tr e pc -ies were et u t in the fie ld east of the University scad i-BULLETIN 6 12 5 um. The first posts were set out in October of 1937. Seven posts of each of the twelve species were not treated. T hey were set our in the test field where they served a dual purpose. They served as a basis for de-termining the relative serv i eab ility of untreated posts of different species, and as a basis for com par ing the length of life of treated and untreated posts. Inspections of posts were made at intervals vary-ing from one year to three years. At each inspection, data on the ondition of the posts were recorded. SERVICE LIFE OF UNTREATED POSTS The number of pOSts of eac h species in serv ice-able condition after different periods of time is shown in Table ] It is apparent that ca talpa, eastern redcedar, and black locmt were durable since most of the posts were serviceab le at least 14 years. The catalpa and cedar posts w hi ch failed during the study were serviceable for a long time, over 10 years; and the failing locust pOSts lasted more than 6 years. The generalization that a large amount of heartwood in a durable species in-creases post longevity was borne Out by the data. The two cedar posts which lasted less than 14 years had Fig. 3. Condition of selected posts after 14 years of service. Left to right-untreated black oak (less than one-TABLE 1 -- PERCENTAGE OF UN'IREATED POSTS SERVICEABLE AFTER VARYING PERIODS OF YEARS. Alter Atter Alter 5 10 14 S~cies Years Years Years Catalpa 100 100 86 Eastern Redcedar 100 86 71 Black Locust 86 86 71 Black Oak 100 29 29 White Oak 86 43 14 Shortleaf Pine 57 29 14 Chinkapin Oak 86 43 None Hackberry 14 None None Slippery Elm None None None Shagbark Hickory None None None American Elm None None None Basswood None None None heartwood diameters at the butt end of less than 3 in ches. The heartwood of the other cedar posts ex-ceeded 3 inches in diameter. The smallest locust POSt fa iled first. However, there was no apparent relation of heartwood diameter to post life in the case of the other species. T he oaks and short leaf pine proved to be moder-ately durab le; most of the posts of these species lasted at least 5 years, but only a small percentage were still serviceable at the end of 14 years. The pine posts had third of the posts are serviceable). untreated catalpa. un· treated black locust, and creosote-treated shorcleaf pine. 6 MISSOURI AGRICULTURAL EXPERIMENT STATION large diameters and were exceptionally resinous ; this combination probably accounted for longer-than-ex-pected serviceability of these species. The other spec-ies tested showed low durability. The results obtained in this study were somewhat similar to those reported in the U S. Department of Agriculture Farmers' Bulletin No. 2049. This study has not been carried on long enough, however, to ob-tain accurate estimates of the average life of posts of the moderately durable and durable species. Analysis of the data indicated that there was no apparent relationship between durability and number of annual rings in the outside inch or the total number of growth rings in the post. SERVICE LIFE OF TREATED POSTS Results of the test of the 11 species treated with creosote (hot bath followed by cold bath) are shown in Table 2. TABLE 2 -- PERCENTAGE OF CREOSOTE-TREATED POSTS SERVlCEABLE AFTER DIFFERENT PERIODS OF TIME1 . Percentage Of serviceable Posts After After After 5 10 14 Species Years Years Years Black Oak 100 100 100 Eastern Redcedar 100 100 100 Black Locust 100 100 87 White Oak 100 100 87 Shortleaf Pine 100 100 87 Chinkapin Oak 100 100 63 Slippery Elm 100 37 25 Shagbark Hickory 100 37 None Hackberry 100 25 None Basswood 87 25 None American Elm 87 13 None 1 2-1/4 hours in hot bath and 1 hour in cold bath. This treatment increased the serviceable life of posts of all species. In the case of the non-durable species (elm, hickory, hackberry, and basswood), trea.ted posts may be classified as moderately durable, lasting about 5 to 10 years. The life of the moderately durable species (oaks and pine) was significantly im-proved by this treatment, most of the posts lasting at least 14 years. T he span of time of this experiment has not been sufficient to determine whether the life of the naturally durable posts (locust and cedar) will be extended by this treatment. In the test to determine the most effective creo-sote method, the foregoing treatment-a 2 lA -hour hot bath followed by a I-hour cold bath-gave the best results for the two species tested. However, all black oak posts given a hot and cold bath creosote treatment on only the lower 2 feet were in serviceable condition after 10 years. It appears, therefore, that treatment of . the entire post may not be necessary for black oak. In the treatment of basswood posts, soaking the entire post gave somewhat longer life than just soaking the lower two feet. , The tests with all types of treatments on black oak and basswood demonstrated that these two species did not react alike. In general the creosote bath treat-ments increased the life of the black oak posts most, but the other treatments, except the carbolineum treat-ment, were almost equally good. With basswood, the zinc chloride treatments gave essentially the same re-sults as the best creosote treatment. Over 80 percent of the posts treated with zinc chloride were serviceable for at least 10 years, and over 40 percent were still serviceable at the end of 14 years. Zinc chloride ap-plied through a tire tube appears especially promising for basswood. All zinc chloride-treated posts had a life of at least 10 years, and 83 percent of the posts were serviceable at the end of 14 years. The Osmoplastic and Osmolit treatments did not lengthen the life of basswood materially, but improved durability of black oak posts. After 10 years all oak posts treated by these methods were still in service. At the end of 14 years, 60 percent of the Osmoplastic-treated posts and 20 percent of the Osmolit-treated posts were still serviceable. Painting posts with either hot creosote or hot carbolineum did not increase durability significantly. Soaking posts in crankcase oil for one week apparently resulted in some increase in post longevity, although none of the basswood posts so treated lasted 10 years. The seven check posts of black oak which received no treatment of any kind gave similar results to those treated with crankcase oil. BULLETIN 612 7 CONCLUSIONS Untreated Posts 1. The species tested may be grouped into three durability categories based on results of this experi-ment: Durable-Most posts will endure for more than 14 years. Catalpa, eastern red cedar, and black locust. Moderately durable-Most posts will endure for from 5 to 14 years. White oak, chinkapin oak, black oak, and shortleaf pine. Non-durable-Most posts will not endure for 5 years. Slippery elm, hickory, hackberry, Amer-ican elm, and basswood. 2. In order to insure long life, posts should be made from a durable species and should contain heart-wood with a diameter of at least 3 inches at the butt end. 3. Rate of growth is apparently weakly related, if at all, to durability differences within a species. Posts Treated with Preservatives 1. The most successful of the preservative treat-ments tested are: (1) creosote used by the hot and cold bath method, and (2) zinc chloride applied either by soaking or through a tire tube. 2. The most effective creosote treatment was a 2 ~ -hour hot bath followed by a I-hour cold bath. This treatment prolonged the life of all species. N on-durable species lasted approximately 5 years longer with this treatment; moderately durable species were durable at least 5 more years when thus treated. 3. Zinc chloride applied through a tire tube by means of the force of gravity was more effective than any other treatment tested on basswood, a soft hard-wood species. All basswood posts thus treated lasted more than 10 years. 4. The simple equipment needed for the two most effective preservative tre;.atments used in this ex-periment is: (1) a supply of creosote, two metal barrels to hold the creosote, and an arrangement for heating the creosote in one barrel for the creosote hot and cold bath treatment; (2) a supply of zinc chloride, a mixing barrel, and a supply of old, truck tire inner tubes for the tire-tube method. 5. Painting the posts with either hot creosote or hot carbolineum is not effective in improving post durability. 6. It is not likely that a soft hardwood, such as basswood, can be improved in durability by soaking in oil or by treatment with Osmolit or Osmoplastic. Black oak apparently will have improved durability after these treatments, but the experiment has not ex-tended over a long enough period to determine the exact amount of the improvement. This project is financed in part by DIVISION OF FORESTRY MISSOURI CONSERVATION COMMISSION 

Tests on treated fence posts

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