Plaster bentonite and silica recipe for casting. Sand sank to the bottom and would not stay mixed. Determine how much investment material you will need for your project. Di is a full time glass artist and tutor in Ohaupo, New Zealand. To cast higher temperature metals like copper base and aluminum you would best use foundry materials for a mold , essentially sand with some binding agent. I am going to use a splash coat of 1 part pottery plaster and 1 part 200 mesh silica. Di Tockers shows how to mix plaster and silica correctly for use in moulds for glass casting. Dude I’ve been trying to come up with my own investment plaster for jewelry casting for a while now I can feel myself getting closer and closer but to make a long story short I’ve found that 100g plaster 100g lime 50g silica flower to give me the least cracks still cracks but the smalles I’ve gotten so I’m still playing with the ratios Fire clay. While the data is extremely useful for design, actual individual samples will probably differ. It's a frustrating process, as by the time the mold has been burn out it is extremely fragile, what with gypsum losing its bound water at the required temps. Jan 28, 2022 · Seven step easy to follow instructions on the sand casting process with images and green sand recipes. Where to collect fireclay in nature and how. What is fireclay? All refractory materials are based on fire clay, alumina and silica. Cast starfish Spooning compound into a plastic candy mold to make starfish castings. The objective was to find the plasticity index of pure bentonite clay, fire clay, china clay, and mixtures of these clays with silica sand. Get step-by-step instructions, essential tips, and equipment advice for your first glass casting project. Temperature and purity will often have a definite effect. However, I can't find the original post or article - I may have imagined reading it Any . Sep 2, 2015 · Adding kilnwash to plaster/silica investment by Peter Angel » Wed Sep 02, 2015 10:42 pm Hello all, I recall reading somewhere that adding a small amount of dry kiln wash to dry plaster/silica before mixing the lot with water result in a very clean cast. The results showed that Attempted mold making investment using Plaster of Paris w/ silica sand. It’s inexpensive, easy to use and wonderfully versatile. A mold made of metal works for low temperature metals . As the silica sand grains become finer, the film of bentonite becomes thinner, although the percentage of bentonite remains the same. We advise overestimating as having a little leftover investment material is better than scrambling to make more while the prior batch is quickly setting. I use a 2 quart pitcher, and fill my molds with that unless they are exceptionally large. Due to reducing the thickness of binder film, the green strength is reduced. The info I have says to use "Gerry's Mold Mix" but doesn't give any recipe for this. Buying fire clay. I've seen people screen the silica before mixing up a batch of green sand, as well as the screening step happening when building a mold for the sand directly in contact with the parent object. The procedure involved making clay paste, determining the upper and lower plastic limits, and calculating the plasticity index. Although both slip-casting and hand-forming techniques are possible, the latter is harder to execute with high percentages of feldspar. Here Guy Michael Davis shares how to mix plaster and pour a 1-piece mold. Sand casting made easy! Keep in mind materials like plaster of paris have water of hydration which can be released although they look dry. I began testing with 40% feldspar and gradually increased the amount until it made up 70% of the recipe, which is the presumed composition found in a parian clay body. You want to make sure you fill the mold in one pour, so that you don’t have any lines in the finished cast. I've talked with an aluminum casting guy that really likes Biasill--says it produces finer detail than the old olivine, makes a more durable mold and gives a better surface that needs almost no cleanup--but it's supposedly bloody expensive. A 50/50 mix of pottery plaster and silica flour is excellent for making molds and for casting elements for kiln sculpture. Like heat resistant mortars, insulation, many pottery clay's, adobe ovens, fire clay can be found in them all and in the mud clay itself. Making plaster of paris more suitable for investment casting with additives? I've tried, like many others, to use plaster of paris (gypsum) to make investment molds. In fact all firebricks are made from fire-clay. Mix in a well-ventilated area while wearing a NIOSH-approved respirator. This lab report summarizes an experiment to determine the plasticity index of various clay compositions. Nov 12, 2003 · Plaster Mould For Casting by Dean Hubbard » Wed Nov 12, 2003 5:30 pm I just finished a clay positive and I'm now preparing to pour my plaster mould for open face casting. (xpost from r/metalworking) I've found a few references to people using 1:1 mix of Plaster of Paris and sand for a mold medium appropriate for casting aluminum. The recipes I've found vary the sand to bentonite ratio from 100:10 to 100:12 and keep the water or oil minimal, but the question on my mind is the mesh. Aug 12, 2011 · This table is a data information resource for the specific gravity of many common general materials. As 1000kg of pure water @ 4°C = 1 cubic meter, those materials under 1000kg per cubic meter will float; more dense materials will obviously Jan 16, 2013 · Playsand typically is rich in crystalline silica, so it's more of a challenge to work with. Make sure you thoroughly mix the slip with a blunger before you begin pouring your molds. Dec 27, 2025 · Learn glass casting with this beginner-friendly guide. Jul 16, 2025 · Learning how to mix plaster is an important skill for a potter to learn. ehn mum wjr goe rrv fed vig suo yeo szg hkc pyy xkh sbb rul