Shiny! The insides of a wasp mouth...

ChrisR · Post by **ChrisR** » Wed Jul 22, 2009 4:13 am

You get smaller crystals if you cool things quickly, whether freezing or by precipitation, so it might be good to do that somewhere aloing the line.
Some chems are far more soluble in warm water than cold, the cooling would initiate faster precipitation in those.

If I remember correctly, NaCl doesn't dissolve much better in warm water than cold. In fact KCL dissolves better in cold than hot - unusual or I'd never have remembered. Low molecular weight sounds good, eg not a sugar, for small molecules/crystals.

I've searched a little for clues for what might form small , regular crystals, but all the documents I find are all about growing great big ones.(When I was a lad a silicon crystal for semiconductors was amazingly big at 20mm, but Andrew pointed out it's now it's more like 300mm!)

Another approach you could try would be a monolayer of a fat molecule.
Methanol or something more pure than the Bitrex/purple stained stuff, like Vodka, with a tiny amount of cooking oil added. Almost none. The fat molecules would repel each other but wind up aligned, more or less, on the surface when the solvent evaporated.

ANother thought - a dye, like Fluorescein or maybe one of the standard micrographic ones. I have some drain-testing dyes I could try.

gpmatthews · Post by **gpmatthews** » Wed Jul 22, 2009 5:49 am

You could try a film coat as a means of altering surface texture. A simple formulation would be something like hydroxypropylmethylcellulose (HPMC - basically wallpaper paste) with up to 1% or so high molecular weight polyethylene glycol (PEG 4000 or PEG 6000, the number is the approx MW) as plasticiser and a trace of detergent as wetting agent all dispersed and applied in water (use less than ~10% solids) and air dried. HPMC could also be used to poison crystal growth so that you prevent formation of large crystals if trying out a fine crystalline coating. HPMC coats are likely to be matt and of lower reflectivity than glossy insect chitin. Other cellulose derivatives, such as methylcellulose will probably work as well as HPMC. HPMC 3 cps (3 cps is the viscosity of a standard concentration dispersion) is commonly used in film coats on tablets. To disperse cellulose derivatives successfully in water, mix with very hot water and stir continually whilst cooling, this minimises lumps which form in cold dispersions (these compounds are generally insoluble in hot water). You can add solids such as talc to film coating supensions to alter the properties of the dry film.

Being water soluble, you can wash coats off and try again if not successful.

Here is a whole new area for experimentation!

ChrisR · Post by **ChrisR** » Wed Jul 22, 2009 6:10 am

I wonder how big "flowers of sulfur/sulphur" are. Or corn starch powder.

I also wonder how fine is the stuff the women stick on their face. Looking though a 40x lens, jolly fine. It seems the more you pay, the finer it gets.

Some numbers:
http://www.shreejifinechem.com/talc_powd.htm
http://www.cxchuangxin.com/pages/talcum-powder.htm

and on this page under mesh sizes there's an interesting suggestion for a 2 micron particle...
http://www.skylighter.com/fireworks/mak ... e-size.asp

rjlittlefield · Post by **rjlittlefield** » Wed Jul 22, 2009 10:15 am

Lots of good suggestions here. Please post more as they occur to you.

Many thanks!

--Rik

Peter M. Macdonald · Post by **Peter M. Macdonald** » Wed Jul 22, 2009 10:35 am

A long-standing technique for photographing fossils has been to coat them with magnesium oxide. You light a piece of magnesium ribbon and hold the object in the "smoke". The particles are very small, although I do not know just how small they are.

ChrisR · Post by **ChrisR** » Wed Jul 22, 2009 10:35 am

Well there's always a
sublime answer:
You really want something which de-sublimes (is there a word for that?) straight from vapour to solid, a bit like your headlamp filament tungsten, but at say 40ºC!
Vapour deposition does tend to produce shiny surfaces, of course

like on camera lenses.
I know industrially they charge things to help the process, like Andrew's needle in reverse. Fine white smoke then? Magnesium? MgO is a small molecule...

rjlittlefield · Post by **rjlittlefield** » Wed Jul 22, 2009 8:10 pm

No change to the coating here, just a different position of the mandible.

I think this works pretty well to illustrate the structure.

I've also included the base of the mandible, since we can see some of the functional anatomy really well in this view. Notice in particular the massive ball joint at the bottom right hand side, and the remains of that huge muscle bundle coming out of the base. These critters may have a little trouble getting their mouths open, but getting them shut again is no problem at all!

105 frames, 0.00033 inches focus step, ZS PMax with mild retouching.

--Rik

ChrisR · Post by **ChrisR** » Thu Jul 23, 2009 1:31 am

It does. Do you have a pair pic before you seasoned it?

AndrewC · Post by **AndrewC** » Thu Jul 23, 2009 2:45 am

I can see this pair, but only by rotating my head to the right, not by tilting. I am very right eye dominant so that might be why.

Graham46 · Post by **Graham46** » Thu Jul 23, 2009 6:12 am

Very nice Rik. This new stereo image really has some striking parts-- the curved tips and hairs are obviously pointing back toward the lens, and the ball joint definitely looks good too. Youre getting good mileage out of this mandible!

AndrewC · Post by **AndrewC** » Thu Jul 23, 2009 8:34 am

ChrisR wrote:....You really want something which de-sublimes (is there a word for that?) straight from vapour to solid,..

Yes, it's called "deposition". It's what I do for a living

rgds,

Andrew

ChrisR · Post by **ChrisR** » Thu Jul 23, 2009 8:57 am

So it is .
Well I don't like it. That means you deposit by deposition. Most unsatisfactory