Masonite

Mashing-in Mashing-off Masking of odors Masks Masonite Mason number Masonry... 

The first industrial hardboard was developed by W. Mason in the mid-1920s he found that a mat of wet fiber pressed in a hot press would produce a self-bonded flat panel with good strength, durabiUty, and stabiUty. The product was patented in 1928, trademarked as Masonite, and commercial production began. Over time several other processes for producing hardboards have been developed from modifications of the original process. Brief descriptions of these processes foUow and a flow chart of the process is shown in Figure 5. 

The slurry is pumped iato another stock chest, where wax ia emulsion form, usually about 0.5—1.0% wax-to-fiber weight, and 1—3% PF resia are added. PF resia is also added on the basis of resia soHds-to-dry fiber. Thea a small amouat of alum is added, which changes the pH (acidity) of the slurry, causiag the resia to precipitate from solutioa and deposit on the fibers. Resia is required ia greater quantity than ia the Masonite process because only light bonding occurs between fibers prepared ia a refiner. The fiber slurry is thea pumped to the headbox of a Fourdrioier mat former, and from this poiat the process is similar to the Masonite process. 

Commercial Masonite and Asplund boards and the asphalt-impregnated insulation board were sampled before any commercial heat treatment. The corresponding "thermomechanical" pulps had been produced by pressurized refining of steamed chips. The higher pre-steaming temperature used in the Masonite process resulted In a yield of about 85% as compared to a fiber yield of about 94% of the Asplund pulps, the remainder being dissolved. 

Figure 5. The rate of isothermal heat evolution on a logarithmic scale versus the reaction time. Top, for a 3.8 mm commercial hardboard of Asplund pulp bottom, for a 3.6 mm commercial hardboard of Masonite pulp. Released heat 1.0 kcal equal to 4.19 kJ. (Reproduced with permission from ref. 10. Copyright 1989 De Gruyter.)...

Left for commercial hardboards of 2.3 mm (open circles), 3.8 mm (open squares), and 6.0 mm (open triangles), as well as for semi-hardboards of 93 mm and density 760 kg/m3 (filled squares), 12.6 mm and density 500 kg/m3 (filled circles) and 133 mm and density 610 kg/m3 (filled triangles), all of Asplund pulp. Also for commercial hardboards of Masonite pulp of 2.2 mm (semifilled circles), 2.7 mm (semifilled triangles) and 3.6 mm (semifilled squares). 

Figure 13 presents the Arrhenius plots for all boards of density between 850 and 1 100 kg/m. Here the hardboard line is the mean of both Asplund and Masonite type commercial hardboards, presented in more detail in Figure 14. There was no significant difference between hardboards from 2.3 to 6 mm thick made of the two related types of coarse thermomechanical pulp. Semi-hardboards...

A thin layer of Masonite (wood veneer) is attached to an insulating layer of glass wool. The Masonite is 2 mm thick. It has the following properties ... 

Painted (flat latex) wallboard Cotton / polyester bedspread Masonite Brick (used) Wool carpet Cement block Wallboard... 

This treatment does not remove the lignin. The fibers are dark in color and very stiff. They are not used in paper manuf nor for the nitration of NC, but can be pressed into a product of extreme durability hardness, known as "Masonite Presswood ... 

Irradiations are carried out in Kimax glass ampoules. These ampoules are filled with 5 cc. of the solution, irradiated, using the apparatus previously described (7), and flame-sealed with a Perfe Keum Model HS-1 ampoule sealer. The irradiation source used for these experiments is a 1.3 X 106 curie cobalt-60 source consisting of two parallel plaques 56 inches wide by 48 inches high, spaced 16 inches apart. For most irradiations, the ampoules are placed in the center of a Masonite phantom which completely fills a No. 10 can (6 inches in diameter by 7 inches high). The can is placed in a fixed position in an aluminum carrier and transported into the irradiation cell to a predetermined position (5). The source is then elevated from the bottom of a 25-foot, water-filled pool into the irradiation position. After the desired exposure, the source is lowered to the bottom of the pool. 

To calibrate the cobalt source, three systems are most often used ferrous sulfate, ferrous sulfate-cupric sulfate, and ceric sulfate. Dosimeters of these solutions are prepared by filling 5-ml. chemical-resistant glass ampoules with approximately 5 ml. of solution and flame-sealing the ampoules. The ampoules are then arranged in phantoms of Masonite or similar materials (Figure 13) to simulate the food items. These phantoms are placed in containers similar to those used for food products, and arranged in the conveyor carrier in which they are transported into the irradiation cell. Because of the upper dose limit of the ferrous sulfate and ferrous sulfate-cupric sulfate dosimeters (40,000 and 800,000 rads, respectively), these systems can be used only to establish the dose rate in the facility and not to monitor the total dose during food irradiation. The ceric dosimeter which... 

Figure IS. Phantom constructed of /fs-inch masonite disks to simulate foods canned in a No. can. Dosimeters shown are made of polystyrene ampules...

Alternatives to grinding include explosive depressurization, which is involved in the Iotech (5) and Masonite (16) processes, ultrasonics (17), osmotic cell rupture, and conventional chemical pulping techniques. Explosive depressurization appears especially promising because of its effectiveness and relatively low energy consumption. 

In Activity 3.1, the students will prepare whiting compounds, substances that impart a brilliant white to a ground, which will be combined with other chemicals to produce a gesso paste. In Activity 3.2, the gesso paste will be applied to masonite board to prepare a... 

Apply the gesso to a masonite board (see item C). Cover the beaker with a watch glass. Store the gesso in a refrigerator between applications (it will gel between applications and should be warmed on a hot plate until it is just melted before using). 

C. Have students create a gesso ground by applying the gesso to a masonite board ... 

Using a utility knife, score one side of a 5-x-7-in. masonite board. 

The rabbit-skin glue or the cottage cheese provide adhesives to bind the whiting compounds into a thick, creamy solution that can be applied to a masonite board and built up layer by layer to form a solid ground. Calcium sulfate and calcium hydroxide dehydrate as the gesso dries and solidify to form a cement ground. They also provide a white solution that is made more brilliant with the addition of titanium dioxide. 

The research reported herein was conducted under the direction of the author when he was Manager of the Basic Research Section, Research Center, Masonite Corporation, St. Charles, Illinois. 

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