A question i am regularly asked is, 'What is End Grain and why can it open?'. In answer to this question, Wooden Garden Furniture that is left outside will naturally absorb moisture from the atmosphere during damp conditions then swell slightly, and to the same extent it will also dry out in warmer climates. This is perfectly normal behaviour for what is essentially a natural product and cracks come and go depending on seasonal variations but rarely do they affect the strength, performance or life expectancy of the item.
The sections of timber that are most susceptible are the end sections or 'end grains' of the timber, predominantly around the frames and arms of chairs where they have been cut and show the growth rings.
These periodic cracks are perfectly normal as the wood breathes and reacts to variations in the moisture content of the air. Cracking on the end grain sections usually happens early in the life of the furniture as the timber settles in to its new climate that may well be very different to that of its native country.
When timber is dried at source, it should be dried slowly and allowed to retain a certain amount of its moisture between 15-18% for the UK climate. This helps to reduce the risk of the end grain opening.
If you have recently bought Teak Garden Furniture, you may find on very hot sunny days the end gain will open. Simply apply a small amount of PVA wood glue into the opening and around, rub in and allow to dry. Sand off with a fine paper (240).
In the event that you leave your Furniture outside during very damp periods, tables and chairs with moving sections may not open. DO NOT FORCE any parts as you may run the risks of breaking timber or brass pivoting parts. The timber may well have swollen a few mm. Put the furniture in a dry place or wait until the the weather dries the timber out naturally. DO NOT SAND the furniture - when the furniture has dried out naturally, you will find gaps in the timber.