trial & error

This weekend I've been testing making molds with silicons. I want to cast a mirror frame I've carved out of wood. I doubted at the time whether to guild it but decided to leave the wood to be seen. Now I want to cast it and see if I can have a gilded version too.




I'd used plasticine to back up the frame. It sticks it down so it prevents it from floating, and raises it enough to let the silicone runs under just a little. That way the casting needs little cleaning up. I used plaster of Paris to cast. But the combination of an intricate and delicate shape with gypsum as medium proofed to be too much to ask. 


It's too weak & came out broke, but I was pleased to see it showed all the detail in the original frame. So the technique works. All i need to do now is find a way to make the mold it in such a way, that the cast will have more strength and lesser change of breaking. 


In this 2nd setup I've let the plasticine run out from under the frame. This way the mold will have more contend. When poured with plaster all the plasticine you see will be filled with it. Hopefully it will add strength to the frame, but it will mean more clean-up after it's released from the mold. This mold is drying as we speak, so I can work on it tomorrow.


I choose gypsum to cast, cos one of it's characteristics is it takes any paint, unlike polyurethane (which is stronger). The broken pieces are a great way to test the gilding. Gilding benefits from a base color to give it extra depth of shine. I'm using fake gold but the same principal applies to that material too. Not too happy bout how it looks so far (broken pieces with cracked finish :)), but no doubt trial and error will make for a better result. Till then, 



UPDATE:

I've added 25% PVA glue and with the added backing it came out in one piece. Yhippy! but I noticed the glue makes the liquid plaster more viscose, and any air bubbles that are in there are less likely to be able to raise to the surface.  A 3th cast is drying, this time I made sure to fill all nooks and crannies with a brush before topping the mold up. Fingers crossed...




15 comments:

  1. I hope it all works out for you!!!

    Seeing the detail in the plaster makes me realize even more how wonderful your carving is!!!

    I wonder, would mixing a bit of glue into the plaster help with its strength???? Well I just Googled and found this http://www.firehow.com/2010040611061/how-to-make-extra-strong-plaster-of-paris-for-casting.html

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  2. Aah Elga, where would we be without you?!? Your link makes perfect sense, I've used the recipe and it's drying as we speak. Let's hope it works together with the bigger backing. I'll let you know asap :) Thanks for thinking along, it's really appreciated!

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  3. Big pleasure and I hope it works!!!!

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  4. Hallo Debora,
    Ik lees [mijn engels is niet zo goed] dat je met gips giet. Ik gebruik voor mijn mallen Kera plus.
    dit is veel harder dan gips. hopelijk blijft dan je gegoten voorwerp dan wel heel.
    succes met de spiegel.

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  5. It works Elga! Still tweaking but the first test with the added glue is promising as you can see.
    Erica, je Engels is prima :), tis inderdaad gips. Porselein gips. Het heeft o.a. de eigenschap uitzonderlijk hard te zijn en zeer gedetailleerd te kunnen afgieten. Ik heb even gelezen welke eigenschappen Kera Plus heeft, maar het lijkt op het eerste gezicht heel erg op elkaar. Ik denk dat het vooral de gietvorm zelf is (dun, gedetailleerd en met vele overbruggingen) die maken dat het model zo kwetsbaar is. Dus mocht eea uiteindelijk niet lukken dan ga ik niet verder met gips-achtig materiaal; dan is de volgende stap toch echt polyurethaan hihi. Evengoed heel erg bedankt voor het meedenken, wordt zeer gewaardeerd!

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  6. There are so many materials you can use to cast these with. I hope you find the right formula for the glue and plaster.

    You could also try a casting resin that has plenty of strength. http://www.creative-wholesale.com/casting%20resin.html

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  7. Magnificent baroque mirror ! I love all your furniture especially your Ikea armchair.

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  8. Je suis certaine que tu vas réussir à trouver le bon dosage. Le petit morceau doré est déjà un véritable petit bijoux!

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  9. I've cast 5 pieces today and none turned out satisfactory :( I guess this piece is just too fragile to use plaster... As you suggested Catherine, I'm inclined to try resin as cast medium now. That will throw a new challenge in the ring; how to guild that material? but I've no doubt that the solution to that will be found :))

    Tam Toum; that chair is a design Bruno Mathsson, made by Kottetoys from Sweden They used to make 1:10 kits, as is my version. I'm glad to tell you that they now have a section of 1:12, all chairs. Go check'm out! Maybe they have some you like?

    http://www.kottetoys.se/ABC.Stolar.Miljö..1..12/ABC.Stolar.Miljö..1..12..Helsidan.htm

    It's all in Swedish but just throw the site in a translator and you'll be fine :)

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  10. OMG Debora!!! This is amazing!
    You are so patient! I tink I would have given up after the first one came broken.

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  11. Have you thought about trying either pewter or alumilite ?
    /Niels

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  12. Yes, it crossed my mind Niels, when I decided on which type of silicon to buy. The one I've bought is not that resistant to be casted with heated media. I could, but the mold wouldn't last as long. And how about detail, and % of tin? Gilding pewter is more or less like galvanizing? Lot's of questions, but besides the research, buying all the equipment and materials is an investment I can't justify, i simply can't afford it.

    Plaster is out of the window... I'm putting my money (haha) now on resin :D Alumilite looks good, thanks for pointing it out. I'll keep you posted.

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  13. Hi Debora,
    The results look promising! The details are amazing on the plaster version. Resin will work better I think. If you put a good primer(spray) on the surface of the resin it can easily be painted! Or otherwhise use the plaster(in layers) and put between the 2 layer a wire(iron) in shape of your frame. But I think the resin will work just fine.
    I've bought some at: siliconesandmore.com
    Keep us updated on the casting!
    Good luck

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  14. Hallo Debbie ,

    Prachtig houtsnijwerk is er weer uit jouw gouden handjes gekomen!

    Misschien kun je nog eens proberen hoe het je bevalt een mal van vloeibaar rubber te maken
    [is in flessen te koop van "Make Me"].
    Is wat soepeler en verminderd daarom de kans op breuk!
    Even experimenteren om de mal niet dikker te maken dan nodig is[mij bevalt 3 lagen goed].

    Veel succes!

    Groetjes,Wil

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  15. Я тоже пробовала залить свою скромную рамку, гипсом. Он очень хрупкий и у меня пока ничего не получилось. Я тоже думаю про смолы. Вы можете посмотреть http://ksandra-tyfilka.blogspot.ru/2013/03/blog-post_27.html

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