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Hardwood Record — Veneer & Panel Section 



July 10. 191 



ture of the glue. Stir the solution gently until the tem- 

 perature has been reduced to the standard point decided 

 on for making the viscosity test — -187 to I 75 degrees F. 

 according to individual desire. 



If a pipette is used to test the flow, insert the lower 

 end well into the solution, and, with the other end in 

 the mouth, draw in until the pipette is full to the stand- 

 ard point. Hold the tube easily between thumb and 

 finger, and with a watch take the time necessary for the 

 solution to run out of the tube. The best results with 

 a pipette are obtained with a stop watch. 



If a burette is used, the solution may be poured in the 

 top, and the tap turned when ready to take the time of 

 the flow. In any case be sure to immerse the instrument 

 used in warm water, before using, and endeavor to have 

 it at the same temperature as the glue solution. 



Another way is to have a copper vessel with a tap — 

 as on a burette — at the bottom. This vessel should be 

 about the same size as the one in which the glue solution 

 was made. It may be warmed, in the auxiliary vessel 

 previously mentioned, while stirring the solution to reduce 

 the temperature. Then pour the solution into this vessel. 

 Now bear in mind that the principle is the same whether 

 the time is taken in letting a certain amount out of a 

 vessel, or in putting a certain amount into a vessel, pro- 

 viding the same method of operation is used. So, if using 

 a large viscometer, have a jelly pan — description fol- 

 lows under jelly tests — marked at a standard point, and 

 take the time necessary to fill the pan to that point. 

 After taking the viscosity test the same glue may be used 

 in making the jelly test. 



The jelly test is based on the comparative resisting 

 power of various glue jellies. In glue factories the "jelly 

 tester" is one who is so expert as to be able to make 

 accurate tests by finger pressure. Various mechanical 

 devices have been perfected for the purpose of giving 

 a quantitative expression of the strength of the various 

 jellies. 



Whatever method is used the jelly should be allowed 

 to cool to a temperature of about 60 degrees F. before 

 taking the test. It will take some time for the glue to 

 come down to that point, anywhere from six hours up, 

 according to what means are used for cooling. Care 

 should be taken not to cool too rapidly, thereby giving 

 the jelly surface a different consistency than the body. 

 For a "jelly pan" in test work the operator may use any 

 cylinder shaped vessel of a size appropriate to the amount 

 of mixture being used. 



The most common jelly tests are the shot tests. These 

 are either very similar to, or modifications of, the original 

 Lippowitz shot test. In this test the glue solution is run 

 into a cylinder and allowed to set. A metal strip, with 

 a perforated center, is slipped over a metal rod, to the 

 lower end of which is soldered a small convex button, or 

 disc. A funnel is placed at the top of the metal rod. The 

 convex surface of the disc rests on the surface of the jelly, 

 and shot are slowly poured into the funnel until the disc 

 penetrates the jelly. The combined weight of the disc, 

 rod, funnel and shot is taken into consideration. The 



greater the amount of weight the jelly will stand, the 

 greater its consistency. The method, illustrated in figure 

 VII, is largely used, and is fairly reliable on glues of light 

 color and of neutral, or almost neutral reaction, but its 

 value must be considered merely comparative, and on 

 glues having a strong acid reaction it is of little value. 



A modified form of this test consists in resting a small 

 brass cup directly upon the glue jelly, and dropping the 

 shot into the cup. When the cup has penetrated to a 

 certain depth, the combined weight of the cup and shot 

 gives a figure which may be used to express a compara- 

 tive strength of the glue with the standard adopted. 



Another jelly test, illustrated in figure Vlll, is made 

 by pouring the glue solution into a cylinder shaped vessel 

 having a diameter of about three inches, and of such 

 depth as to allow the glue layer a thickness of I J/2 to 2 

 inches. This may, of course, be varied according to the 

 vessels at command, but it should be the same for all 

 samples. While the solution is still warm, a circular 

 metal disc one inch in diameter, to the center of which 

 is fixed a stout wire, is inserted. The wire is kept in a 

 vertical position, by any convenient means, until the 

 solution has jellied. The vessel is fastened down, and 

 the wire attached to one end of a stout balance. Weights 

 are then placed in the other pan of the balance until the 

 disc is torn through the jelly. The greater the weight 

 the tougher the jelly, and the stronger the glue. It is 

 claimed for this method that the variations due to the 

 surfaces of glue jellies are obviated. 



There are more accurate and complicated methods of 

 making these tests, but it is believed that those described 

 will be found easily applied in the average factory. 



Smooth Cutting as Quality 



Smooth cutting is distinctly a quality in veneer, whether it 

 be sawed, sliced or rotary cut. Its importance depends some 

 upon the use of veneer, whether it is fillers of plain stock to «e 

 used in builtup lumber with other fine finish or whether it is 

 face veneer. But smooth cutting plays a prominent enough part 

 to be classed as an important element in quality. 



If it is sawed veneer, saw marks make necessary extra heavy 

 sanding to finish off the veneer, and this means more than the 

 extra work it costs. Heavy sanding is seldom so well done but 

 what it will impair the quality of the face and finish. The ideal 

 finished face is one which is very smoothly cut so that light 

 sanding and scraping will finish it off. It is then one gets the 

 best in both texture and figure effects. There is no bruising, 

 battering or distorting of the fibers by heavy sanding, and the 

 face presents when finished a live, pleasing appearance. 



The same thing applies to sliced or rotary cut veneer. If 

 there are gaps or bruises on the cutting knife or pressure bar 

 which make scratches on the face, the face must be sanded or 

 scraped off until all the scratch disappears. This means not 

 only extra work, but the possibility of actual damage to the 

 face wood in the process of cleaning. Where veneer is cut 

 very thin, as is quite commonly the case today, heavy sanding 

 or scraping to finish off rough cutting may spell ruin to the whole 

 job. 



So any way we look at it, rough cutting is objectionable and 

 smooth cutting takes on distinctively an element of quality. The 

 time is here, too, when discriminating buyers look to the quality of 

 the wood and likewise consider the beauty of figure in face veneer. 



