Southern Pine Association Makes Moisture Contents Part of Grading Rules

A twelve-page booklet detailing the principal reasons why lumber is seasoned and giving the moisture contents recently adopted as rules of its grade-marking practice has been issued by the Southern Pine Association. The booklet relates some of the history of lumber drying and shows that the practice dates back to antiquity and was recognized in both the Bible and in the Latin poet Virgil's works as a "hardener" of wood. It tells of the modern practices in both air and kiln drying and of their effectiveness in producing better and stronger lumber.

The Southern Pine Association calls attention to the prevalent wasteful practice of builders who cover or protect every item of construction material except the framing lumber. This, it points out, is inviting subsequent disalignment of the structure frame, the most important element in the building. The booklet explains how moisture equilibriums are established through the long seasoning and drying processes; how proper seasoning tends to eliminate warping, checks, knot loosening and other possible defects from the delivered product, and how, when lumber is carelessly exposed a second time to the elements, the established equilibrium may be so badly broken down that failures will result.

Because of the equilibrium factor the booklet cautions against specification of unreasonably low moisture contents. Moisture contents below those given in its Standard Specifications for Southern Pine mav be obtained from Southern Pine mills, it states, but in announcing the availability to purchasers of its official inspection service on deliveries, it makes the point that lumber ordered on special moisture content specification will not be considered as falling under the grading rules, but as a special contract.

The announced moisture Content Soecifications in the Southern Pine grading rules are: Kiln Dried l. For C and Better Lumber-4/4 and S/4-Uitn dried, the moisture content shall not exceed 12 per cent in 9O per cent of the pieces of a shipment, or an item of a shipment, and the remainder shall not exceed 15 per cent.

2. For C and Better Lumber-6/4 and 874-61tt Utt.U, the moisture content shall not exceed 14 per cent in 90 per cent of the pieces of a shipment, or an item of a shipment, and the remainder shall not exceed 17 per cent.

3. For No. 1. No. 2 and No. J Common Boards and Strips-kiln dried, the moisture content shall not exceed 15 per cent in 90 per cent of the pieces of a shipment, or an item of a shipment, and the remainder shall not exceed 18 per cent.

4. For No. 1 and No. 2 Dimension-kiln dried, the moisture content shall not exceed 15 per cent in 90 per cent of the pieces of a shipment, or an item of a shipment, and the remainder shall not exceed 18 per cent.

5. If, and when C and Better lumber 4/4 and 5/4 is air dried, the moisture content shall not exceed 16 per cent in 90 per cent of the pieces of a shipment, or an item of a shipment, and the remainder shall not exceed 19 per cent.

6. If. and when C and Better lumber 6/4 and 8/4 is air dried, the moisture content shall not exceed 18 per cent in T p.t cent of the pieces of a shipment, or.arr item of a shipment, and the remainder shall not exceed 21 per cent.

7. For No. 1, No. 2 and, No. 3 Common Boirds and Strips-air dried, the moisture content shall not exceed 19 per cent in 9O per cent of the pieces of a shipment, or an item of a shipment, and the remainder shall not exceed.22 per cent.

8. For No. 1 and No. 2 Dimension-air dried-the moisture content shall not exceed 19 per cent in 90 per cent of the pieces of a shipment, or an item of a shipment, and the remainder shall not exceed 22 per cent.

Inspection and Shipping

9. These moisturi content provisions-apply at the time of loading the lumber.

10. Purchasers desiring stock of a specific moisture content,.higher or lower than the figures given herein, may obtain it by ordering it special, and such a shipment stritt be considered not as having been manufactured under these rules, but as a special contract.

11. In case of complaint on account of the dryness of any shipment of Southern Pine lumber, official Asiociation inspection will be available to subscribers and to non-subsciibers upon request. Such inspections for dryness will be made in accordance with the maximums allowible under these rules; inspection service for "special" moisture content limitations shall be rendered only when the exact specifications are furnished to the inspector.

12. In case the buyer wishes inspection as to moisture conteni he shall notifv the shippir within tw;t-i;;; hours after the lulnber is unloaded. All lumber on which complaint is made as to moisture content must be fullv protected from the weather; no inspeciion will be made ii, upon the arrival of the inspector, there is evidence that these provisions have not been strictly complied with.

13. ff, as a result of an official Association inspection, it should be found that some of the pieces of a shipment, or an item, exceed the maximum moisture content illowable herein, such pieces shall be considered ds of the next lower grade. It is understood that an item of a shipment will consist. of -a grade and size, without reference io lengths, except ll tltg case of dimension that is ordered in quant-itiei of specified lengths.