[0:17]So this is a trunk of a hard wood tree, and again we have the, the axis, the longitudinal access and the radio and of course, the tangential, which runs at 90 degrees to the radio.
[0:30]If we first of all look at this plane here, which is the radio longitudinal plane. Now if you remember with the the hard woods, the um the structure hard wood is we have lots and lots of fibers.
[0:43]And then between those fibers we have not in every case, but in quite a few cases with hard woods, we have these bundles of ray cells which are called multi seriate rays.
[0:56]So if you take a section here, a radio longitudinal section of a hard wood, that's going to look more like this. We still have the growth rings running in this direction.
[1:10]But much more visible now will be the rays running through and they may run all the way through the section or they may kind of wiggle in and out, but you're much more likely to hit the rays because they're these bundles are so big.
[1:25]And this can give very attractive appearance to the wood and it's quite often referred to as the figure of wood. And a classic example of that is if you look at oak, which if you split it along the radius, will give very attractive patterns and quite often with furniture,
[1:44]wood is deliberately cut in this direction, which is known as quarter sawn and uh the reason for that is to give a very attractive appearance to the wood.
[1:58]Some species this is more um successful than others because it really depends on what the the clusters of ray cells look like.
[2:06]So that's one of the big differences between hardwoods and softwoods when you look at a section on the radio.
[2:12]But also we have these pores running down through.
[2:18]A bit hard to draw here, but they can be quite visible. In things like oak, these pores can be quite big and oak is what's known as a ring porous.
[2:24]So if we were looking at the the growth ring here, there'll be a lot of pores put down in the spring when the wood starts growing and there's a requirement for conduction of sap up through the wood.
[2:37]So each growth ring in oak is made up of lots of these pores in a ring porous structure.
[2:44]And this again can be very visible. So oak is one of those species that is used because of the appearance of quarter sawn especially.
[2:52]Ash can also be very attractive.
[2:58]That has uh ring porous structure, but the rays are not so visible in that particular case.
[3:02]So with hardwoods there's a lot more differences that you get with different cuts.
[3:07]So if we were to look at a tangential cut of the oak, the appearance there would be we'd get these growth rings, which are of course, made up of these pores, but we would see the multi seriate rays rather more obviously.
[3:22]So they'd be showing up. So with a softwood because they're uniseriate, you hardly see them at all on that particular direction.
[3:33]And then of course we have this plane at the top, which is the transverse plane, and then you'd be looking down and you'd be seeing these pores.
[3:40]So you can use these sorts of features to identify different wood species.
