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Glue Economy 





Editor's Note 



The importance of glue to the panel manufacturer is too well known to need argument. The accompanying 

 article, read by .T. W. Beiger. mechanical engineer and glue expert. Mishawaka, Ind., before the National Veneer 

 and Panel Manufacturers' Association in convention at the Auditorium hotel, Chicago, December 10-11, 1912, gives 

 some valuable suggestions on the subject. 



We will for a few minutes look at the source 

 and manufacture of glue. The organisms of all 

 animals, but more especially of the higher 

 classes, contain tissues which are insoluble in 

 cold as well as hot water. However, by con- 

 tinued boiling, they become dissolved and yield 

 on evaporation of the solution a glutinous 

 mass. By further drying this mass exhibits, ac- 

 cording to the degree of purity of the material, 

 a more or less transparent and brittle sub- 

 stance, which in its pure state is devoid" of color 

 as well as odor; it swells up in cold water 

 and dissolves upon being heated in that 

 liquid. This substance — that is, the con- 

 version of the so-called glue or gelatine 

 yielding tissue — is what is known to the trade 

 as glue. 



Keither glue nor gelatine exists ready formed 

 in the animal organisms, except under abnormal 

 conditions of disease, but they are the products 

 of various transformations. 



The raw materials used in the manufacture of 

 glue consist of a variety of animal offal. The 

 principal substances employed are refuse of tan- -T- W. EEIGER, 



yards, such as scraps of ox and other thick hides, the waste of work- 

 shops of leather dressers, etc. Tlie tendons and intestines of many 

 animals, rabbit and hare skins deprived of their fur, cat and dog 

 skins, scraps of parchment, waste of tuners and button makers, and 

 the offal of butcher shops and households help to swell the series of 

 materials used for the manufacture of glue. 



The materials are collected and sold either directly to a glue boiler, 

 or to a dealer making a specialty of glue stock. The glue stock is 

 then placed in large vats containing a strong solution of lime water. 

 This frees it from all fleshy and bloody particles, and especially 

 decayed matter. The stock is then treated with an acid so as to 

 neutralize and preserve it. From here the stock is placed in large 

 kettles and boiled. After separating it from all settlings and grease, 

 it is put into coolers and allowed to chUl, forming a stiff jelly. The 

 jelly is then sliced and dried. It is then run through a crusher and 

 broken up. This is the commercial appearance in which it is gen- 

 erally found. 



So much for the source of glue. 



A matter in which you will be more interested is how to determine 

 the value and grade of a glue at the time it is delivered at your 

 plant. There are few places where the consumers are equipped to 

 scientifically analyze glue, and to those who are not it will be inter- 

 esting to know just how this work is carried on, so that the covering 

 capacity as well as the strength of a glue may be determined before 

 any of the glue in question is put into the spreader. 



This system is of vital importance to you, for without it it is 

 rather dangerous business to experiment with a glue out in the plant 

 and then put the reputation of your house back of that glue. 



The glue manufacturer grades his glue in some eases by viscosity, 

 in others by the stiffness of the jelly and the remainder by the price 

 he can get for anj' old glue. 



Taking the first means of testing, we wiU look into that and see 

 of what value it is to you. By viscosity, we mean the body or thick- 

 ness. For example, take milk and cream. Milk is thin and has a very 

 low viscosity, while cream is thick and has a high viscosity. The 

 above will also serve to explain that the viscosity of a liquid has 

 nothing to do with the specific gravity, and cannot be determined 

 by any floating glass instruments or hydrometers, which so many of 



the consumers believe. 



To determine the viscosity ot a liquid wo 

 allow a constant volume of that liquid to flow 

 out of some containing vessel through a small 

 opening at the bottom, and catch the time re- 

 quired to empty the vessel. The time in 

 seconds is the viscosity, and the instrument 

 is called a viscosimeter. 



The value of this instrument to you can 

 best be explained by an example. We will 

 take the following conditions of a glue con- 

 sumer — he is using a glue at 10 cents a pound. 

 The viscosity of that glue in 'a 33.3 per cent 

 solution is 1.3 seconds. Now he wishes to de- 

 termine whether a certain glue he has received 

 is worth the price quoted, and if a more eco- 

 nomical glue for him to use. He will there- 

 fore make up a small batch of the glue in 

 question and take its viscosity in a 33.3 per 

 cent solution. We will assume that the result 

 of that test was 10 seconds. That being the 

 case, one thing is certain, the glue in question 

 does not make • up as heavy a liquid as the 

 MIsriAWAKA. IND. glue he is using, therefore it will be necessary 



to add more of the test glue to the solution, so as to bring up its 

 viscosity. By the use of tables and curves, he is able to determine 

 that the glue in question will have to be made up in a 37. .5 per cent 

 solution so as to have the same viscosity as the glue he is comparing 

 it with. That is, the glue he is generally using has a viscosity of 15 

 seconds in a 33.3 per cent solution, while it takes a 37.5 per cent 

 solution of the test glue to give the same viscosity. 



From the data now at hand it is an easy matter to figure the 

 value of the glue, and the result of that calculation gives S.9 cents. 

 'Therefore, this is the value of the glue to our consumer, and he 

 will have to buy it at that price in order to get the same efficiency 

 out of it as he is getting out of the glue he is using generally. 



So that the above line of reasoning will be better understood, the 

 following statement should be made: A batch of 100 pounds of 

 liquid glue having a viscosity of 15 seconds, will cover the same 

 amount of surface, if used in the same glue spreader, on the same 

 kind of work, at the same temperature, regardless of the amount of 

 dry glue there was put into that batch. Viscosity determines spread. 

 The word viscosity seems like a very scientific expression and is 

 generally pronounced with great stress. But, gentlemen, it is only 

 a term that tries to explain what every practical user of glue has 

 endeavored to determine, the exact thickness of the body of glue. 

 However, by the use of a viscosimeter there is no guesswork, and once 

 the proper body of glue has been established for your work, you can 

 always maintain that body, regardless of the grade of glue you 

 have' at hand. By being able to maintain a uniform body you have 

 taken one step toward uniform work, and one step toward uniform 

 co^t of work. 



While this system is not being used universally as yet, it is going 

 to be used more and more as time goes on. It may seem strange to 

 you that while tliere are a great many manufacturers of glue in this 

 country, no two of them produce the same grades of glue, and 

 stranger still, not any one of them can produce exactly the same 

 - grade from daj- to day. Each boiling must be analyzed for its 

 grade. That being the case, unless you are checking up the quality 

 of glue as it is delivered to you, there must be a variation in the 

 grades of your glue. A statement of facts on this variation will seem 

 very large, but there has been found on shipments of glue from the 



