This article is from the Woodworking FAQ Collection 1, by multiple authors.
Yes, hide glue is graded in terms of "gram strength". 85, 108, 135,
164 192, 222 ,251, 283, 315, 347, & 379. The higher the gram
strength, the quicker the set. Generally it is recommended to use
#251 gram strength in woodworking. There is also bone glue and fish
glue.+
What other hide glue tidbits are there?
Hot hide glue has the advantage of creating a "rubbed" joint. By
simply using hot glue, you can place a block in a difficult place to
reach by rubbing the block back and forth to remove the excess glue
and holding in place for a few moments. The glue will begin to cool
and gel immediately eliminating the need for a clamp. The " wetting"
properties of hide glue can be increased by adding approximately 1%
vinegar.
 
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