Gluing a project together is unquestionably one of the most stressful parts of an otherwise wholly enjoyable experience. It can take days of worry and sleepless nights to work out the correct procedure for bringing it all together – get any of it wrong and you’re in jeopardy (or similar) up to your hat band!
Should you do the whole thing in one hit, two or even three? Glue brush or application stick, cleaning rag, water? What cramps and how many? Cramping blocks?
The biggest issue, surprisingly, is the weather, which has a direct impact on the type of glue used. There’s no doubt that the modern PVA adhesives are great to use and are the ‘go to’ choice for a vast number of woodworkers. They can be applied easily, straight from the bottle, in exactly the correct amount and the better ones, such as Titebond II and III are fully water resistant. It’s not recommended that they be used for continuous immersion in water (as in boat building), but they’re fine for outdoor projects where a good soaking from the rain and damp conditions won’t make any difference.
All glues have an ‘open time’, which is the period of use before they start to set and the higher the ambient temperature, the shorter that time is. Which means that on a stinking hot July day, any PVA glue will have an ‘open time’ of less than ten minutes which also means that if your assembly is going to take 30 minutes, you’re into ‘hat band’ country!
Some time ago, faced with this problem of the short ‘open time’ in warm weather, I resorted to using urea-formaldehyde glue, the infamous Cascamite of old which I first used in the 1970s. It’s totally water resistant with an ‘open time’ of over an hour in hot weather and will fully set in about five hours, although in a very cold workshop, the job needs to be left in cramps for 48 hours! The disadvantage of Cascamite is that it sets glass hard and is ruinous on edge tools if you need to clean any off the work – planing concrete is probably easier.
Having sorted out everything needed, I decided that the table was best glued in two ‘hits’: the inner frame and then the legs with the two connecting rails. Glue was mixed to the right consistency (it should just drip of the end of the brush) and applied to both parts of the joint with a small paintbrush and the frame knocked together with a white rubber mallet.
Sash cramps with soft blocks under the heads are then positioned either side of the stub tenons to pull them together, after which the holly wedges can be glued and tapped home. It’s crucial that every single last smear of Cascamite is removed from the joint. I use a cut down glue brush (rather like a stencil brush), scrubbing it away with just a dab of water and a clean rag to dry it off afterwards.
The cramps are then removed (the joint’s not going anywhere now) and the remaining legs and rails fitted dry (no glue) to ensure that everything is ‘hunky doodly’.
The area round the joints is waxed after polishing and this acts as a ‘resist’ so the glue won’t stick to it. Simply peel off the Cascamite after about an hour when it’s set to a rubbery consistency.
The final bit in this long drawn out saga is to give the tenons a final squeeze with a few G cramps.
Gluing up can be a nightmare, but if the ‘little grey cells’ are all lined up it usually works out successfully. The glue is the real problem as both sorts, PVA and urea-formaldehyde, are both excellent products, but each has its own disadvantages.
Should a glue manufacturer formulate a PVA with a two hour ‘open time’, not only would they be sitting on a pile of gold sufficient to make Smaug turn green with envy, but they would, at a stroke, have found every woodworker’s Holy Grail.