GLUE FORMULAE

by John T. Kramer

Antiques Doctor & Apothecary

Traditional cabinetmaker's glue is made from boiled and purified hooves, and sinews of horses and oxen. In general use there are two types; dark "Scotch" and light "French" sold both in cakes and ground. Glue made from the sinews of old animals is stronger than that made from the young. By soaking a piece of glue in clear water for a day or two the bad quality will dissolve so it can be poured off leaving the good glue swollen ready for preparation.

For general work a good plan is to use dark and light glue in equal measure. For particular work in light color wood use only the light "French glue."

To prepare glue for use it should be broken up and placed in a double boiler type glue pot or one of the newer temperature controlled electric glue pots with enough water to cover. Boil steadily until the glue has melted. Remove any impurity from the surface and test for consistency. The glue should run from the brush in a steady stream and make a slight rattling noise in the pot. If the pot is kept boiling, thinning with water is necessary every time the glue is used. Glue must not be allowed to get hotter than boiling water.

A thin coat of glue in a tight joint is better than a thick coat in a loose joint. Let any glue that oozes out chill and then scrape off while still a jelly, wash area with a damp cloth.

To keep glue fresh in the pot keep a twig of willow or dogwood soaking in the gluepot at all times.

LIQUID HIDE GLUE

Soak broken or ground glue in strong vinegar to cover. When swollen, stand vessel in hot water and add more acid to desired consistency. Keep container tightly stoppered when not in use.

ISINGLASS

Also known as fish glue is prepared in a similar manner usually mixed to a thinner consistency. It is made from the air bladders of sturgeon and is used for very fine work, marquetry, veneering and gilding.

FISH GLUE

The more proper glue designated fish glue is made of the skins of eels or large perch. It is mixed and used like hide glue but, is finer and clearer. It can be melted without the addition of water when controlled heat is applied. It has been used extensively for gluing laminates for bows and by rod manufacturers for assembling fine split tonkin and calcutta cane fly fishing rods. When a strong glue is needed for tight joints that are subject to flexing this is the traditional choice.

WATERPROOF GLUE

To waterproof glue prepared in the ordinary way, while it is hot add 1 part bichromate of potash for every 2 parts of cake glue used. Once prepared the glue must be kept in the dark (in a lidded stone jar) until required; once exposed to light it becomes insoluble.

MARINE GLUE

1 part rubber

20 parts shellac

12 parts coal-tar naptha

Evaporate to dryness after dissolving and combining. To use warm and apply thinly.

EGG GLUE

Used for fine repair and gold leafing.

8 egg whites

1 gill water

Mix thoroughly, ready for immediate use.

If you are assembling any wood parts which are required to move against other wood parts; i.e., bearings, drawer slides, whimsies, &c. ALWAYS use dissimilar types of wood working against each other, the woods will wear better and stick less. The best example of this I can think of is many years ago, in the Boy Scouts, I was taught that to make a fire by friction (bow or hand drill against a fire board - rubbing two sticks together can't work) to use a hard against a soft wood. I gave up after considerable effort in abject failure.

Many years later I learned from a group of experimental historians that only matching woods work; the softer the better; western red cedar or cottonwood, dry and well seasoned, are good choices.

The point is that similar woods bind and increase friction when worked together a hard against a soft resists friction. In this regard hard versus soft refers to the properties of the wood not necessarily deciduous vs. conifers. More about all of this later.

Three old lubricants will solve your stickiest shop problems. Sweet Oyl (olive oil) is used to coat metal tool parts for lubrication and rust prevention; it won't stick and gum like linseed oil and you don't risk staining the wood like with petroleum based oils. If cutting edges (saws, drills, augers, plane irons, chisels, &c.) are first pulled through a chunk of beeswax to coat the edge the work will be eased; screws drive easier if threads are first coated.

A cake of lye soap is handy to lubricate sticky drawer glides and other wood against wood bearing surfaces where the maker used similar woods bearing against each other.

Rosin is useful for increasing friction.

Sweet oyl

lye soap

beeswax

tallow is also useful if you like it.

All that's needed in a traditional wood shop for lubrication.