[Nhcoll-l] Clear Acrylic Blocks

[Simon Moore]

Hi Lena,

I have had experience in making these blocks.  They don’t always turn out well but 80% look good.  
I use polypropylene. moulds which don’t need a release agent.  The specimens must be 100% dry or dehydrated in several immersions of acetone - the slightest presence of moisture will cause misting and shrinkage (silvering).
Practise on something non-valuable first. Use 1 drop of peroxide catalyst for every 10g of resin and you will need to do it in several layers or your specimen may float: 1st layer is a top coat (inverted), when gelled but still sticky add your specimens (inverted), wait a further 20 minutes for resin to ‘anchor’ it in place then add a second layer of resin to cover the body only (in case it pops off the bottom layer), then add the 3rd and final layer when the 2nd layer has hardened enough (you will know) and leave the 3rd layer overnight.  Cast out the block next day and leave for a further 24 hours to completely harden and not on a flat surface or it may adhere!
Then grind the sticky (and concave) side until flat, then polish on a high speed wheel with polishing compound.  When doing this last process, get someone to show you - too much pressure ‘burns’ the resin and if the wheel catches the top of the block it will startlingly (and painfully) flip the block out of your hands.
As I said quite a bit of work but as you grow more skilled and can do 20 blocks a day, much easier and quicker.

With all good wishes, Simon.

Simon Moore MIScT, RSci, FLS, ACR
Conservator of Natural Sciences and Cutlery Historian,
www.natural-history-conservation.com 




> On 4 Oct 2017, at 18:17, Lena Hernandez <LHernandez at themosh.org> wrote:
> 
> Hi all, 
>  
> I had a question come in from our education folks. They would like use some of those insects preserved in clear acrylic for a program. The issue is they are having difficulty finding the exact species they need, so they decided to try making their own with the help of our exhibits team. Has anyone done this before? The few instructions that they have found online did not result in the nicest looking finished product.
>  
> If anyone has any pointers or links to references on how to make these, it would be most appreciated!
>  
> Lena
>  
> Lena Hernandez
> Collections Manager & Registrar
>  
> Museum of Science & History
> 1025 Museum Circle
> Jacksonville, FL 32207
> (904)396-6674 x212
> lhernandez at themosh.org <mailto:lhernandez at themosh.org>
>  
> <image001.jpg>
>                                                
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>  
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