mystery boning- physics and chemistry

[glittersweet]

Several years ago I managed to find several lengths of lovely rigid plastic boning. I have not found anything like it ever again. I do have some of the now readily available boning variously known as German Plastic Boning and Synthetic Whalebone (which may or may not refer to the same thing) but they just are very different for purpose.

I have a BSc in Biochemistry so plastics/resins hold a real fascination. I mean obviously I had to learn a fair bit about the resins used in fibreglassing because it changes how you use it. For example when to laminate and when to work the entire thickness- basically each batch you mix and cure becomes one giant molecule, each separate batch then only bonds to the surface- it’s more complicated but basically this is also why I like to use fillers and thinners with the same product- that surface bond is still not to be sneezed at. I am so allergic. To epoxy. Polyester is just nasty. But the pros of epoxy as basically safety; flex and resistance to flame.

So. I have a sample and I can do a few very simple tests to find out what the primary plastic is. But plastics are not pure, they may be made from several sources and may have additives and these will affect physical properties.

I don’t think I have enough for professional testing but I should be able to follow this, with a bit of help:

https://www.modernplastics.com/wp-content/uploads/2015/03/how-to-identify-plastics.pdf

Of interest is this: melamines smell like fish and formaldehyde! I definitely have a few samples of this.

The cut edge is very similar to the cut edge of the Wissner product as stocked by all the main sellers. It goes opaque with compression in the centre of the cross section. It is not a pure clean cut either, the edge is somewhat flaked. It doesn’t crumble. So already that is a test.

I can easily test density-ish. If it floats in water (“room temperature”) or sinks.

So I will see how it burns- speed to catch, smoke, smell, flame, drip…

I can’t quite tell if there is pigment. It is cooler in tone than the other boning but it’s quite subtle. And it could be a matter of different pigments vs presence or absence of pigments. Zinc oxide vs Titanium etc. etc. There might be a bluing pigment?

I have been trying to find the boning online and the easiest way to identify it is the cross section. It is much more oval than what is readily available. And that cross section adds to the rigidity.

In part this: https://en.wikipedia.org/wiki/Torsion_constant because it is harder to twist. But mostly because of
https://en.wikipedia.org/wiki/List_of_second_moments_of_area

So sewing huh. Physics and chemistry do matter. It is not just an issue for support materials like this! Fabric is an exquisite interplay. The fibre content, the processing, the spinning, the weaving, the dyeing, the sizing.. it all affects whether you can even wash a fabric without losing properties. And that then affects what you can do to dye or stitch or store the fabric.

Cutting fabric is a calculated risk in very many ways. You cannot restore a fabric to precut. It’s not just a matter of aesthetics. It will affect the kind of stitching and fibre content and thickness and twist of thread used to sew it back together. Hand vs machine is not even a given. The fabulous cloth of gold fabric from Sartor Textiles was a dream to machine sew with tiny stitches and the smoothest polyester thread I can use with a microtex needle. Slightly harder to hand sew and it really really needs to be pressed with heat.

Anyway.

Time for a break.