Jigstones

[JCSteam]

I have a couple of moulds for jigstones, my problem is whenever I have tried to cast the blocks, I always have bubbles at the bottom, so there isn't as much detail as there should be, any tips??

[MDLR]

1) Use liquid concrete (the runnier the better)

2) drop the filled moulds from a height of round about 1" onto a hard surface - this will help to dislodge the bubbles.

[JCSteam]

1) Use liquid concrete (the runnier the better)

2) drop the filled moulds from a height of round about 1" onto a hard surface - this will help to dislodge the bubbles.

Thanks for that, never tried step 2, so maybe thats where I am going wrong, tried paste, liquid, and mixing cement with equal sand (very brittle), will give it a try

[JCSteam]

Ive done a bit of searching and found a website I not seen before by MrJigstone himself, plenty of useful demo videos and inspiration on there

http://mrjigstones.webs.com/jigstones-demos

[andymctractor]

Be careful about making the mortar mix too weak. Very runny goes in easier but you may find you end up with a weak casting.
I found it more effective to use a thickish strong mix and not to mix more than you have time to fill the moulds with before it starts to go off. I put a small amount of mortar into the mould and pushed this into all the internal corners before gradually filling the rest of the mould. Use a flat piece of wood or similar to wipe excess mortar off the top of the mould. You could also try tapping the top of the wet mix to improve the casting.
Finish off by dropping the filled mould down on a hard surface to release trapped air bubbles as previously suggested.
Be patient don't try to remove the casting until it has set. Once set and removed, leave it a couple of days to properly harden.

Good luck

[LNR]

I've not used jigstones, but the problem you describe is common to many moulding processes. I would definitely second what Andy has said about applying a thin layer first and working it into corners and detail in the mould. Being thin it is easier to work out trapped air, and assures at least a bubble free outer surface. Good luck.
Grant.