Disasters in casting

10 am – My latest attempt made last night, was looking very good until

I tried to remove it from the mould –  it broke . . .

third failed casting

I have learned at least three things from it though – mix up one large batch not 2 smaller ones, add a retardent so that I have more  control, remove it from the mould more carefully.

Fourth attempt coming soon.

3pm Tuesday – I have made another casting pouring the whole thing at once, instead of in two layers. I could not get the surface to be smooth whilst the plaster was wet and have done a lot of scraping back with various scrapers. Its not as smooth and even as I’d like but its OK. I must now be patient and not try to take it out of the mould/wok until tomorrow. Then I hope to be able to fix the small imperfections., remove it from the mould and make the second half.

fourth casting

32 hrs later  8pm GMT – the casting is out of its mould and in one piece! although the scauce-pan lid is firmly stuck in the centre. Experience suggests I leave it well alone, the whole thing kind of slid out of the mould at lunchtime today 1pm GMT – with a little coaxing but the lid is stubborn and has decided to stay where it is a little longer. The outer surface is looking good albeit somewhat stained with rust and felt-tip pen. I think I will sand that off in the morning. Showing here, the stained exterior and the still-lodged saucepan lid.

Fourth casting de-moulded - looking good

Several days later (Friday) the casting is hard and almost dry, I managed to succesfully  remove the saucepan lid but later on several fine cracks appeared and its is in danger of breaking apart. The very kind man at Maragon casting suppliers, suggested that the cracks are almost certainly caused by my having added a wee few drops of citric acid to the mix to slow down the setting period when I needed extra time to smooth the interior surface. He suggests adding a fresh layer without the acid, to the inside to strengthen the structure.

I might just start again as the rust marks, also caused in some part by the citric acid but mostly caused by the long time it takes to set, are almost impossible to remove entirely. (I will heat the next one very gently in the fan oven, to speed up the elimination of the water content and reduce or even prevent rust forming.)

Cracks in the drying casting

5 thoughts on “Disasters in casting

Leave a Reply

Please log in using one of these methods to post your comment:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.