![]() ![]() But it is advised that surfaces should be additionally sealed to survive outdoors.ĭefinitely the medium is more ‘agreeable’ to use compared to plastic resins. It is claimed that polymer-modified plaster will survive outdoor conditions, not only because of general strength but also because the surface is more sealed against atmosphere and moisture. For example SP201, available from .uk is first added to water in the ratio 2:1 water to polymer. Some acrylic polymer formulations are available which are meant to be mixed with water first, rather than added to the plaster as they are. Instead the liquid needs to be added on top, as one would when making dough, followed by thorough stirring until the mixture is even. but the thickness of the polymer liquid means that the plaster can’t be just sprinkled in as one normally would. This makes it a similar proportion to the usual powder to water ratio when mixing hard casting plasters normally. The usual recommended mix ratio is between 2-3 parts plaster to 1 part polymer liquid by weight. although this is just one of many versions, and any so-called alpha plaster can be mixed with an acrylic polymer liquid with similar results. Most people will know it by the brand name Jesmonite. non-toxic, non-flammable, no smell, easier to work with etc. The invention is commonly marketed as a ‘friendlier’ alternative to resin, especially when sculptors and home-users are targeted. so much so that it has been compared to resin. When plaster is mixed with this instead of the usual water it still undergoes normal setting but the resulting solid is significantly tougher and less porous. ‘Polymer-modified plaster’ is one of the terms in use to describe the combination of plaster with an acrylic polymer liquid. Details of suppliers are listed in the Suppliers section. If a crucible cracks you will want to stop using it.These page entries are meant to be added to and usually start with general outline information, price guidance, suppliers and useful links followed by my worklog where I can put further info and photos as they come. It seems to be pretty easy to address by simply setting the crucible on or in some hot coals after use so it can cool slowly. Get your crucible a little warmed up before you put it into the refractory by placing it on some hot coals.Ĭlay crucibles can handle the heat but you do have to treat them a little different then a metal crucible. Once they have cooled they will sound like a coffee cup when you flick it with your finger? ![]() This may sound like a bit of a tough thing to do if you don’t have a kiln however it’s really not that bad. They need to be cooked in a kiln or some form of kiln to around 2300 degrees Ferenhight and held near that temperature for around 45 minutes to an hour. If you have access to a kiln you’re all set if not you can make one real quick with some fire bricks. So I changed the cooking of recipe 2 through 6 with extremely improved results. This can be a bit annoying especially since it takes some time to get them ready. The first time I tried using them they broke from the force of the Borax expanding inside of them. I tried cooking recipe 2 and 3 with the charcoal method but found they didn’t get hot enough to develop much strength. If it has any cracks it will fail if you use it. If everything went well you should have a crucible that sounds kind of like a coffee cup when you flick it with your finger. Run the hair dryer for about an hour longer then let the whole thing cool in place over night. Let it run until the coals have burned down about half way and add a few more on top. ![]() Once they are glowing red hot you can put the dryer duct in place and start the hair dryer on low. Place it on something so you can fit the dryer duct under it. Fill the rest of the chimney starter with charcoal. Place the crucible in the middle of the chimney starter. Place the charcoal in the bottom of the chimney starter. Get some charcoal, a chimney starter, a bit of dryer duct and a hair dryer to cook your crucible. This will help to burn off all the stuff in the clay that can contaminate the metal you may be melting and it will set the clay to make the crucible stronger. After your crucible has dried you will need to cook it before you use it. ![]()
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