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etching

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Posts posted by etching


  1. I spoke to the slip supplier and he had never heard of this happening except once in the 90's with bought moulds and earthernware slip, he said they never found the cause but he suspected it was faulty moulds. He aslo feels that as I did my plaster mixing by eye (waiting for it to form a mountin etc ) this is the cause. But the thing is this made a strong plaster mix, there was no water left to settle o top when I poured the moulds so wouldnt this be less week?

     

    Anyway he said that as there have not been any oher complaints that it can't be the slip as the produce a huge amount per batch?

     

    I now have to make new moulds, I have a new batch of the slip and 1ltr left of the old. I'm going to use one of the new moulds and just use the old slip on it and the rest will have the new slip. If it was the slip the set aside mould will fail while he others will be fine. I will also mesure out the water and weigh the plaster this time.

     

    I still don't see how old original mould that was fine until I used this slip started to laminate if it was a plaster issue :?

     

    Thankyou all for your advice :)


  2. Marcia:

    Something troubles me about this particular circumstance. All the molds started doing it at the same time; some new, some several years old.

    1. Have you changed slip supplier or recipe?

    2. Did you recently store household chemicals nearby? ( looking for acids evaporating)

    3. Did they freeze and thaw several times?

     

    Nerd

     

    I'm using a comercial slip. This is a new slip for me and I'm just about to finish the bucket 10 L... A friend is also using this slip probably not the same batch and she is not having an issue. It's a popular slip here in Australia.

    No, no freezing of the moulds, they are kept in a studio indoors. They are all kept on a bench so nowhere near any chemicals. The is also no deteriation on the outside only on the internal surface which is breaking down :/

     

    The ony other difference is that I have never worked my mould so hard before with daily use and neither has my friend that also uses the same slip. She will go hard for a couple of days and then nothing for a week for so where I'm pouring into them daily (once only) they take awhile to dry,  but they dont seem to be getting that wet at all. This last batch of moulds I have  been using since the 15th of June so for a few weeks! The last pour yesterday the were all fine and out of the 5 moulds yesterday that I removed the form from 3 had left some plaster behind. I do aways pour these 5 togther though so i must be a usage thing rather than a plaster ratio which I'm sure is fine. The moulds don have signs of being week.

     

    The other thing with that plastic clay is that it doesn'tt have anywhere near the water content so if its a matter of being over used then this wouldn't cause the same issue. I don't use these moulds with plastic clay only slip.

     

    :/


  3. Hi there, I thought someone here may have the answer to this frustrating issue.

     

    I have been slip casting and all of a sudden some of these molds started transfering layers of plaster to the porcelain slip after using them for some time. Some of these moulds were a couple of months old some were a couple of years but they all started doing this at the same time. 

     

    I made new moulds and they started doing the same thing after about 15 casts.They all staretd ddoingit at the smae time again. Loosing fine layers of the plaster onto the porcelain slip cast clay. 

     

    I have attached some images below both of the moulds and the porcelain with the plaster attached.

     

    Also some extra into

     

    Also there is no other obvious deterioration of the mould on the outside. Only the small fine layer that has peeled off inside.

    I am casting a piece a day.

    It is winter here, but I have a heated studio.

    I'm using imperial porcelain slip.

    These moulds I made myself out of potters plaster and are part moulds.

    I cast very fine works 2-3mm thick

    They are from different batches of plaster the first and second time. I alowed the moulds to completely dry before using them (no dampness transfered onto newsprint overnight)

    The moulds that I use plastic clay in are fine!

     

    Any ideas? I have asked around a bit in my circle but so far everyone seems perplexed. One thought is that I'm not letting the moulds dry out enough between times. That maybe casting once a day is to much for a plaster mold to take? I' needing to make a lot of work using these designs so I am casting daily and letting the moulds sit over night empty, but it is cold. I'm desperate to keep using them.

    post-86537-0-95734300-1498911670_thumb.jpgpost-86537-0-09763900-1498911714_thumb.jpg

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