GEOFFREY Posted February 15, 2022 Report Share Posted February 15, 2022 I add UGM at Bisque to my powdered glazes and also I have added to some brush on glazes which were rather "runny" water down. Should I also add some Bentonite powder OR do they both do the same job of help glaze stick and avoid crawling etc? Thank you very much for any advice. Link to comment Share on other sites More sharing options...
Babs Posted February 15, 2022 Report Share Posted February 15, 2022 Bentonite used to keep glaze ingredients in suspension usually a glaze with Ballclay or Kaolin doesn't need it. Only if glaze is hardpanning do you need to consider this and even then a tad of saturated Epsom salts can sort it .This also allows for better glaze application. If ever using Bentonite, mix it thoroughly with dry Ingredients before adding water, then slake glaze. Bentinite swells consIderably when wet. Crawling usually dusty or oil from fingers prob and too thick application of glaze. Book: Hamer and Hamer Authors "The potter's Dictionary of materials and Techniques" a good bible, forums here and Digitalfire 's Tony Hansen worth looking into. Link to comment Share on other sites More sharing options...
GEOFFREY Posted February 15, 2022 Author Report Share Posted February 15, 2022 Hello and thank you. Please what does the addition of UGM have on the glaze? What is hard panning? Yes i'm total novice! Link to comment Share on other sites More sharing options...
Hulk Posted February 15, 2022 Report Share Posted February 15, 2022 "...tad of saturated Epsom salts can sort it .This also allows for better glaze application." ^ that! A glaze can be wet (or thin - more water, low specific gravity) and still gel really well. My glazes, between 1.41 to 1.47 specific gravity, allow me plenty of time for application - I don't have to hurry to keep from the glaze layer getting too thick, yet they don't run and drip either, due to tweaking the thixotropy with a bit o' Epsom salt solution. Going a bit wetter and dialing the gel in has made glazing fun for me! Not too thick, smooth, no drips, no hurry. Huge thanks to Tony Hansen, Sue McCleod, some regular contributors to this forum for explaining. How to Gel a Ceramic Glaze - YouTubeThixotropy (digitalfire.com) Thixotropy (digitalfire.com) I don't know what ugm is. Hard panning, when the suspended particles fall to the bottom o' the bucket form a leathery layer that is very resistant to gettin' stirred back up - rather annoying, quite! How much a fan of tweaking thixotropy am I? Search this forum, "thixotropy" - count the Hulk hits... Link to comment Share on other sites More sharing options...
PeterH Posted February 15, 2022 Report Share Posted February 15, 2022 4 minutes ago, Hulk said: I don't know what ugm is. Possibly Contem Universal Glaze medium (or similar)https://www.bluematchbox.co.uk/ctm-universal-glaze-medium-1kg.html Link to comment Share on other sites More sharing options...
Min Posted February 15, 2022 Report Share Posted February 15, 2022 4 hours ago, GEOFFREY said: I add UGM at Bisque to my powdered glazes and also I have added to some brush on glazes which were rather "runny" water down. Just to clarify, you added Underglaze Brushing Medium or ? Link to comment Share on other sites More sharing options...
GEOFFREY Posted February 16, 2022 Author Report Share Posted February 16, 2022 Contec UGM as pic, THANK YOU Link to comment Share on other sites More sharing options...
Callie Beller Diesel Posted February 16, 2022 Report Share Posted February 16, 2022 The suppliers’ websites that I could google up don’t post any safety data sheets about the UGM, so I can’t tell exactly what it is, other than a brushing medium. If you are mixing glazes from a powder form that are meant to be used as a dipping glaze, they’re generally too runny in that state to be used as brushing glazes as well. To get the same brushability you find in a bottled glaze, you need to add some kind of gum or medium, kind of like how they manufacture paint. Medium usually consists of some kind of flow controlling ingredients that make the glaze the right consistency without adding too much water. Usually it would include some kind of gum, which will harden the glaze and help it stick to the pot, and a preservative to make sure it doesn’t stink. There could be other ingredients in there too, depending on the brand. Bentonite is a clay that absorbs water and expands really easily. It’s usually added to a dipping glaze that you’ve mixed yourself. The particle size of it, and the absorbent characteristics help the other glaze particles stay suspended in water to prevent hard panning, and it helps harden a glaze a little too. Bentonite is pretty powerful, and is used in percentages of 2% or less of the dry weight. Much more than that, and it can gel a glaze, making it apply poorly. It’s absorbent properties can boost the power of any gelling agents in a brushing medium, or with Epsom salts. Bentonite doesn’t play especially well with flow agents like dispex, which again can be in mediums. It can work in small quantities, but it’s VERY easy to upset the balance. While brushing medium and bentonite probably could be used together, I wouldn’t attempt it unless I knew more about the properties of the specific medium. Mixing the two could work, or it could turn your bottle of purchased brushing glaze into an unusable sludge. Adding a medium to a premixed glaze can also be risky if the medium already in the glaze isn’t compatible. I’d call your supplier to see what their recommendations are about combining the two. If your prepared brushing glaze is too thin, the most foolproof method of fixing it is to evaporate some of the water off and mix thoroughly so there’s no lumps. Link to comment Share on other sites More sharing options...
GEOFFREY Posted February 16, 2022 Author Report Share Posted February 16, 2022 THANK YOI Link to comment Share on other sites More sharing options...
GEOFFREY Posted February 16, 2022 Author Report Share Posted February 16, 2022 SORRY spelling THANK YOU Link to comment Share on other sites More sharing options...
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