There are 14 species of Hemlock in North America; Eastern Hemlock, growing from the American Midwest to the Atlantic and from North-central Ontario and Quebec to Georgia and Tennessee, is the most common of these. Historically, Eastern Hemlock has had many uses. Primarily it was used as heavy timber in frame construction and in crates for transportation. Its bark, which contains very high components of tannin, was used extensively in the leather tanning industry of the early industrial era.
Hemlock wood is light brown in colour, odourless and moderately light. It holds paint and glue well. Once dried, it holds nails extremely well. Hemlock burns very fast and hot, leaving few ambers and coals – unlike hardwood. It is therefore a preferred fire-wood for maple sugar producers. Hemlock lumber has developed a poor reputation. Radial shake, if extensive, leads to failure of the lumber. However, radial shake can be readily detected and logs affected by it, sorted for other uses. Hemlock knots are extremely hard, to the point where sawblades are known to shatter when sawing into them. Overall, Hemlock is considerably harder than pine or spruce. For this reason alone the latter were preferred over Hemlock by sawmillers.
Hemlock is a very stable wood. The tannin content protects it from insect attack and makes it more durable in outdoor applications. Hemlock logs are often stored for several years in log yards before being sawn. By that time no insect or fungal decay, which would have severely devalued any other conifer as well as most hardwoods, can be detected and the lumber produced is as fresh and stable as the day the tree was removed from the forest.
By using its favourable properties, which are combined by its use as heavy timbers, Hemlock offers one of the most durable and stable applications for log home construction. That is why Hemlock is being used exclusively by EcoLog, which has designed kits for over 200 Hemlock log homes throughout Eastern North America, building on a century old tradition. Century old log homes throughout Eastern North America were built with Hemlock, being testament today of Hemlock’s durability and strength. Mennonite barns in Southern Ontario, to this day, are built almost exclusively of Hemlock, utilising the wood’s superior qualities, its resilience and stability.
Ecologically Eastern Hemlock is one of our slowest growing trees. This has to do with its ability to endure shade. Often young Hemlocks can sustain themselves for decades, growing one needle at a time, waiting for the opportunity to catch enough light to grow even in later years. Frequently seemingly young, since small, 3 or 4 feet tall Hemlock seedlings, are already “seniors” with 50, 60 or even 70 years of age. It is this slow growth, which provides Hemlock wood with its strength, much superior to pine or spruce.
Hemlock is making up for its slow growth by its proliferation; the small Hemlock seeds are being produced by the millions, germinating readily wherever mineral soil is exposed. This explains the frequency of Hemlock regeneration along roads, where construction has created a suitable seedbed.
In central Ontario Eastern Hemlock is the most common of all evergreen or conifer trees. At Haliburton Forest, almost one in every 10 trees growing in the forest is a Hemlock; and this despite an ecological twist, which makes the germination of young Hemlock seedlings under a mature Hemlock canopy very difficult. This natural, biochemical mechanism, where older trees are combating intraspecific competition is referred to as allelopathy.