How To Use Glue

For glue to be properly effective it requires to penetrate the pores of the wood, and the more a body of glue penetrates the wood the more substantial the joint will remain. Glues that take the longest to dry are to be preferred to those that dry quickly, the slow drying being always the strongest, other things being equal. For general use, no method gives such good results as the following: Break the glue up small, put it into an iron kettle, cover the glue with water, and allow it to soak twelve hours. After soaking boil until done. Then pour it into an air-tight box, leave the cover off until cold, then cover up tight. As glue is required, cut out a portion and melt in the usual way. Expose no more of the made glue to the atmosphere for any length of time than is necessary, as the atmosphere is very destructive to made glue. Never heat made glue in a pot that is subject to the direct heat of a fire or a lamp. All such methods of heating glue cannot be condemned in terms too severe. Do not use thick glue for veneering or joints. In all cases work it well into the wood, in a similar manner to what painters do with paint. Glue both surfaces of the work, except in cases of veneering.

Never glue hot wood, as the hot wood will absorb all the water in the glue too suddenly, and leave only a very little residue.

Preventing Glue From Cracking

The addition of a little chloride of calcium to glue will prevent its cracking when exposed to considerable heat.

Strong Glue For Damp Places

For a strong glue which will hold in a damp place, the following recipe works well: Take of the best and strongest blue enough to make a pint when melted. Soak this until soft, pour off the water as in ordinary glue-making, and add a little water if the glue is likely to be too thick. When melted add three tablespoon-fuls of boiled linseed oil. Stir frequently, and keep up the heat till the oil disappears, which may take the whole day, and perhaps longer. If necessary, add water to make up for that lost by evaporation. When no more oil is seen, a tablespoonful of whiting is added and thoroughly incorporated with the glue.

Waterproof Glue

Dissolve 1/2 ounce each of gum sandarach and mastic in 8 fluid ounces of strong alcohol, to which add 1/2 ounce of turpentine. Put the dissolved gums into a double glue-pot, add by degrees a hot thick solution of glue to which isinglass has been added, stir the whole over the fire until all the ingredients are thoroughly incorporated. Next strain through a cloth while hot, and it is ready for use. It may now be returned to the glue-pot, and 1/2 ounce of very finely powdered glass added to it. It should be used quite hot. Take of shellac 3 parts, india-rubber 1 part by weight. Dissolve each separately in ether free from alcohol. It is best to do this in stoppered bottles and without heating, as the ether readily evaporates.

When solution is complete, mix the two, and keep well stoppered for use.