SCUTUM, building and testing, some thoughts

[Hibernicus]

For this to be true you'd have to prove that the grain density is sufficiently different to have a significant effect on the shield's performance. Personally, given the fact that it's the construction, i.e. 3-ply alternating direction, that gives the scutum the lion's share of its strength, I would doubt that slightly tighter grain would be a signficant factor.

Lion's share of strength... I disagree.
All factors are crucial, not equally crucial: glue type, glue quality, presence or absence of fibers, materials used to skin the scutum, its chord, its laminations as "plywood", varieties of woods.. some may be a greater part of that lion's share than others.

Tighter grain is harder to compress.. the lateral strips if they were denser ( old growth or slow growth) would be harder to crush or cut through than wood grown using modern growing techniques. Modern growers often select fast growth rates or hybrids of tree species that grow fast.. means that a tree gets to market sooner.

Again, you'd have to prove this- I know of at least three species of wood that were used for shields- sycamore, birch and oak- so clearly the requirements weren't that stringent and again because it's the plywood nature that is the major strength of the design, unless the wood is full of knots or something, I can't see major selection happening.

First, I do not believe that there were requirements. It seems quite clear by the evidence that scutum makers knew that a stronger less flexible vertical core laminated between two layers of more flexible more compressable species was the best way to make a scutum.

Thus, I can see selection happening especially if selection is possible. Why not? It's practicle.

I can see trees grown specifically for use in making scutums. Growing wood for specific purposes is something that's been done throughout history. Why not something as important as a military item?

A good wood worker always picks the best parts of a tree for his needs if he can. I use clear ash for pilum shafts, but if after milling into usable lengths and widths the grain does not run right or if a knot is in just the wrong place I reject it. When I select 2x4's at the lumber yard they dread me. I pick the best pieces. I often bring a tool to snap the metal band around a stack of lumber so I can have access to more choices... not all 2x4's a are created equal!

The addition of sinew fibers and the rough face for increased gluing area I understand, but why would you want to glue the strips wet?

That's easy... first I did not state wet wood I said damp. When wood is damp it absorbs glue better. When wood dries water is drawn out, but when you're gluing you want the glue to penetrate into the wood for better adhesion. As the dampened wood draws the water in it also draws the glue.

Wouldn't demand and situation also dictate what type of wood is used? If the "best" choice wasn't available, I'd be interested to see what was used in a pinch.

I was referring to the woodworker's desire to pick the best sections of a tree but I agree that in a pinch other choices might have to be made.

... In fact, I'd wonder if the inner layer of plywood wasn't some different type of wood, and the outer pieces something else. Kind of like how the japanese sandwhich highcarbon steel around a lower carbon steel core in their swords. Gives'em good flexibility but retains a lot of strength.
If not, be interesting to see if they used maybe a lower grade wood in the center, ...

Stronger less flexible wood for the verticals.. ash or oak.

And if you're going to give all this information here on the RAT, why don't you post a few pictures too instead of making anyone who'd like to see them join your Yahoo group- it's a whole lot easier

No one has to join our yahoo group. Some photos are posted on Roman Army Group as well. The photo essay will appear on the Legio IX Hispana web page in due course.