Joined: 11 Mar 2017
|Posted: Wed Nov 06, 2019 8:56 pm Post subject: Steedman's Wax - 50g $35
|Dr. H.F. Steedman invented a polyester wax for ribbon sectioning on standard rotary microtomes in 1947. It consists of 9 parts by weight Polyethylene glycol 400 distearate melted at 60C with 1 part cetyl alcohol added.
As an infiltration, embedding, and sectioning medium, Steedman's Wax has a number of advantages over paraffin for amateur microtomists or anyone without access to a fume hood.
In particular, unlike paraffin, Steedman's Wax is miscible in most alcohols at 95% or above, thus there is no need to use nasty and stinky solvents like xylene or toluene for infiltration, embedding, and clearing. The waz tolerates water reasonably well, so that even does away with the need for scrupulously dry solvents. Most other usual microtomy solvents work well with it, too.
Another positive feature of Steedman's Wax is that infiltration and embedding are done at 37C, which tends to reduce hardening.
When admixed with about 1% beeswax or bayberry wax, reports of good success using Steedman's Wax to section traditionally difficult-to-retain materials such as chitin insect tissue has been reported.
In spite of the fact that every few years an article comes out extolling its virtues, Steedman's Wax never really caught on in a big way, so there are not many suppliers.
There is a good deal of literature on the web about the stuff. Workers recommend that you heat it only once to make, then once again to use it. After that, it starts to lose its sectioning and ribboning qualities.
The problem is that it's expensive and hard to find, and there have been reports of inconsistent quality of pre-manufactured Steedman's Wax from suppliers. It also is today sold only in rather large quantities (500g for $150 from EMS) or more.
To defray the expense of mixing up a batch for my own use/experimentation, I am offering packages of the ingredients for mixing it up yourself and giving it a try. Each package consists of 45+grams of PEG 400 distearate (Spectrum Chemicals) weighed out in 5 aluminum weighing pans of about 9-10g each, a baggy with 6g of cetyl alcohol to add to the PEG when melted, and two baggies each having 0.25g of bayberry wax and beeswax that that may be added at rate of 1% for improved holding power. With a scale and hotplate you can make any variation on the wax you wish in an appropriate quantity.
I have four of these packages available at $35 each including shipping in the US. Drop me a note if you want one.