Document xjn4doYagapvjrMqnDQQ4KbZQ

1966 National Safely Congress fibers, tbc less strength in the leather. Leath er used lor welding and heat gloves lias gone through an additional wash-to remove more of the animal fat; then chemicals arc added which enhance its heat resistant prop erties. In the process of building up leather heat resistant properties, there is a sacrifice in its wear properties. No tanner has yet discovered how to treat leather to give it equally superior heat and wear resistance. The weight of leather used for hand pro tection depends on what type of safeguard you arc using. Naturally, a hand pad or mitten can be made out of a heavier grade than a finger guard or glove. Most welding, heat, and steel reinforced gloves and mit tens arc made of medium weight leather. A special tanned heat resistant leather is desirable for use on asbestos gloves and mit tens requiring leather reinforcement. Dex terity docs not permit the use . of heavy leathers. Leather should be cut so the grain runs lengthwise. The stretch of leather is in the opposite direction to the grain and therefore should run across the palm of the hand so it will stretch when the hand is clenched. Leather performs best where the mate rials being handled arc dry. The presence of oils, acids, and water causes leather to become slippery and deteriorate rapidly. Steel staples can be used to provide addi tional reinforcements on leather gloves, hand pads, and finger guards, which arc designed to meet a wide variety of cutting and abra sive hazards. Finger guards offer good pro tection with a minimum sacrifice of dexter ity. There arc especially useful on small punch press work, sorting, burring, polishing, assembly, inspection, etc. We would like to point out that leather safeguards can be designed to give additional protection to whatever wear point is pre senting a problem to you and can be customdesigned to solve specialized problems. This is the reason for the great number of differ ent style hand pads, gloves, mittens, and finger guards being used by industry today. It is up to your company and your safety apparel supplier, to decide what will satisfac torily do the job for you. The commercial value of asbestos depends largely on two physical characteristics -- its incombustibility and its unique fiber struc ture. Asbestos cloth is converted into gloves, mittens, hand guards, and finger guards. A common question asked by the asbestos safeguard user is, "Mow hot an object can lie handled?" This question cannot be accu rately answered without knowing what the exposure time and temperature factors arc. Thermo-analysis investigations conducted in the research laboratory of the Asbestos Textile Institute reveal that, up to approxi mately 1,490F., the asbestos structure is stable. Above this temperature, it is perma nently altered and inverted to another nonfibrous crystalline structure -- olivine. How ever, at 750 F. there is notable deterioration in fiber quality through the permanent de pletion of some of the structural water of crystallization, and at 1300 F. the structure is nearly completely void of the hydrous elements. This table shows effect of heat on the tensile strength of asbestos. Original crude -- no heat Tensile Strength fsi Percent of Original Tensile Strength 131,000 Heated 3 Minutes at 600F 120,000 91.6% Heated 3 Minutes at 800F 96,000 73.3% Heated 3 Minutes at 1,000F 78,000 59.5% Heated 3 Minutes at 1,200F 42,000 32.0% It should be remembered that the temper ature of the material being handled is not the same as the oven temperature. Instru ments arc available which can measure this important difference. Experience and research has established that the optimum asbestos content by weight is between 80 per cent and 85 per cent. That which meets this specification is referred to as imderwrUers grade. Heat resistance and wearing properties of asbestos cloth arc determined by the fol lowing factors: 1. Asbestos content 2. Type of filler 94