stonegarden Posted November 11, 2015 Report Share Posted November 11, 2015 I've been using Marilee's lava glaze, and like the effect, but ran across a product at Menard's yesterday that got me wondering, could a lava glaze be made with a good bit of coal slag in it? The product is called Black Blast, and is made for sandblasting. It is 99% pulverized coal slag, and looks like crushed black glass. The material data sheet on it noted a melting temperature of 2500 degrees. Has anyone tried using this in a lava-like glaze? I am going for a very rustic, rocky surface for planters and bonsai pots. Link to comment Share on other sites More sharing options...
shead34 Posted November 11, 2015 Report Share Posted November 11, 2015 im pretty sure you can make a lava glaze out of most glazes by adding silicon carbide . im not sure what amounts but im sure you can find the percentages if you google it Link to comment Share on other sites More sharing options...
stonegarden Posted November 30, 2015 Author Report Share Posted November 30, 2015 Photo of a test out if the kiln today: the brown patch on the end is a small pile of the Black Blast; the brown bob in the middle is BB mixed into iron oxide wash; the grey-black blob on the end s Marilee's lava glaze, worth black stain added, and a large percentage of BB stirred in. I as not measuring anything for this first test, but results are promising. Link to comment Share on other sites More sharing options...
stonegarden Posted November 30, 2015 Author Report Share Posted November 30, 2015 Not sure if hoot is going to,show Link to comment Share on other sites More sharing options...
High Bridge Pottery Posted November 30, 2015 Report Share Posted November 30, 2015 Interesting, so it is kind of a frit made from melted ash? Found some chemistry. http://www.optaminerals.com/Abrasives/Blackblast-Coal-Slag.html Is it cheaper than standard rocks? Symbol Name PercentageSiO2 (Silicon Dioxide, Total) ~46.5%Al2O2 (Aluminum Oxide) ~22.5%Fe2O3 (Iron Oxide) ~19.0%CaO (Calcium Oxide) ~5.5%MgO (Magnesium Oxide) ~1.0%TiO2 (Titanium Oxide) ~1.0%SiO2 (Crystalline Silica) <0.1%Loss on ignition (LOI) ~3.0% Link to comment Share on other sites More sharing options...
stonegarden Posted December 15, 2015 Author Report Share Posted December 15, 2015 The ingredient list looks familiar, from my perusal of Menards safer data sheet for Black Blast. It is a repurposed product sold for sand blasting. Fairly fine texture. For a 50# bag, I think it was well under ten dollars. I just got a few pots out frm bisque firing that had this material, and one or two with crushed granite, as well (chicken grit, at the local feed store), pressed into the clay. I will give them a light wash with iron oxide, maybe try a watered down clear glaze, and fire to cone six. Pix to follow, good or bad! Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.