...so what happened when I was making the big mould? Now it's all over and the ending is happy, I can tell you.
Everything was ready to go. The master was polished and carefully levelled. The big tin of silicone, catalyst added, carefully stirred and looking like very sticky custard, was ready to pour.
The Captain was looking on.
It was time to take the plunge and pour.
Ah but I should have known from his wicked grin that I'd done something wrong!
And so I started pouring. Carefully and slowly and all was good. 5 litres of silicone, just enough to fill the mould.
No leaks, then I realise the master was beginning to float!
You learn a lot at moments like this don't you. I tried not to panic and put my hands in the sticky goo to push it back down - gloop, gloop -great big sloppy bubbles came out. It slid sideways so I pushed it back to more or less central. All that time levelling it, wasted. So now I had to stand there holding it down (and it really wanted to float up and was very slippery and sticky) Luckily I got the quick set catalyst. Only 3/4 hour or so before it set enough to let go. And as I stood there arms aching I went over my stupidity. I had done small moulds before and fixed the master down with double sided sticky tape so I did the same for this one but of course it's bigger. Lots of air. Air lighter than silicone, wants to float up. In hindsight I should have glue gunned it down. Next time!
Anyway it set in the end. You can see the holes where my fingers were holding it all down and how much silicone disappeared. I had to buy another litre of silicone and hope that was enough to level it.
It wasn't quite but that was it.
I'd spent enough. I'd sort it out somehow.
So because it wasn't quite enough there was a bit of a curve and the base would need support. It would just flop round the edges when I turned it over the way it was and my resin blocks would be really distorted.
Solution. I made it a fibreglass bottom so when I turned it over and took the master out, it would stay flat.
But had it worked? I still had no idea if all that drama meant it now had bubbles and missing bits. After days of work it could all be useless.
I knew when I turned it over I would have to cut the big slab of silicone out that had 'disappeared' underneath the master. And here it is. Great, I will use it to make a wall so I can split the mould and make rectangular things in it. This was my plan anyway so nothing wasted.
What a relief, not a single bubble and beautifully smooth. It had worked!
Then another problem. Getting it level again.
Not such a problem in the end. I sat the mould on its fibreglass tray, on a board, with big blobs of silicone (nicked the bathroom sealant my husband was using recently to reseal the shower) and got it level from the inside. It is very important it is level as I want the blocks to be the same depth and so far they have been a bit uneven. I intend to re-level the three I have already made using this mould.
Then I gave it a wooden jacked to support the sides and it was ready to go.
This is the first time I used it.
It's great knowing it isn't going to leak out the edges and it's so easy to get the blocks out, then there it is ready for the next one...
... it was definitely worth all the effort.
I love my new mould.