Perth Museum and Art Gallery have revamped their natural history gallery. On the wall,they have a large slice of a tree trunk on to illustrate growth rings. They decided that they wanted some text laser engraved onto it to describe how the rings are created, and how to count the light and dark rings correctly. They asked LaserFlair if we could help.
This was our first question for the Museum. We had no idea if we could even fit the slice into the laser machine. It was roughly 900 x 900mm and 100mm thick, so it did fit snugly, and the laser bed was able to drop down far enough to accommodate it.
Paul thought that a nice deep engrave would give a lovely 3D effect to the text while being easily readable. He thought that laser engraving would age well. At the last refit, white text that had been printed on and it had flaked off over the years.
A deep engrave
Paul sent us an artwork file with the text that they wanted engraved. As the text was quite fine and the engraved area relatively small, we engraved using a lower speed than we would normally use for wood, but using the same power. This ensured that the engraving would be crisp and deep. We wanted to avoid using a very high power that would require the wood to be sanded afterwards in order to remove any burned resin.
Engraving results were good, but the wood was dense which affected the depth of the engrave, making it shallower than we had hoped for. So we engraved a second pass which gave the depth required for the finish that Paul wanted, whilst keeping the insides of the letters strong.
This extra depth of engrave also highlighted the dark and light growth rings. On the less dense spring growth, the engrave was deeper. On the dark, denser summer growth, the engrave was shallower. This beautiful effect is unique to the grain on a piece of wood.
The tree slice is back in its rightful place in the gallery and looks fabulous. Here’s what the text says.
How old is a tree?
Inside a tree trunk are the growth rings. You can count the number of rings to find out the age of the tree. Each ring consists of a light and a dark band. The light band is the wood produced in spring when the water is being taken to the buds and leaves. In late summer, growth slows down producing the dark band. This dark wood gives strength to the tree. On the outside of the trunk the bark protects the tree against animals, fungi and disease and stops the tree drying out.