The uses given for temper colors are not meant to be absolute; they merely give a good general idea; experienced men are guided by results, and temper in every case in the way that proves to be most satisfactory.
DIFFERENCE BETWEEN CRACKS AND SEAMS.
When temperers find that their tools are cracking under their treatment, they are apt to assume that, as they are working in their ordinary way, there must be something wrong with the steel. It is either seamy, or harder than usual, or not uniform in temper, or it is of inferior quality.
All or any of these conditions may exist and be the cause of the trouble; but every man should bear in mind that he is also a variable quantity; he may be unwell and not see and observe as closely as usual; there may be a long spell of unusual weather giving him a light differing from that to which he is accustomed; or, as is often the case, he may simply have unconsciously departed from the even track by not having his mind carefully intent upon the routine which has become a sort of second nature to him, so that for a time he ceases to think, makes of himself an animated machine, and the machine left to itself does not run with perfect regularity.
If personal pride, egotism, or ill temper be set aside, it is always easy to find out whether the fault is in the steel or in the man; that once determined the remedy is easily applied, and the sooner the better for all parties.
How to Break a Tool. Let an ordinary axe be considered.
If the axe be cracked as shown in [Fig. 1], the corners have been hotter than the middle of the blade; probably by snipping the corners and the middle and comparing the fractures the coarser grain at the corners will tell the tale.