Understanding Pottery: Chapter 8 Glaze Chemistry Part 2

[@matheusmachadoalfradique6151]

Wow! There are no words to describe how thankful I am to be able to get this level of knowledge for free. Thank you for sharing and please keep up with the good work! ^^

[@WashingtonStreetStudios]

Matheus, We will keep sharing! Please enjoy the videos and share them with our friends and fellow potters!

[@dccreations1361]

Please never stop these videos, such great videos. So informative.

[@WashingtonStreetStudios]

Unfortunately Phil passed away in July of 2021. New videos will be coming when I get a handle on the main business of running the community studios and pottery school!

[@dccreations1361]

@@WashingtonStreetStudios yes, I found that out sorry after posting this comment. Just about ruined my day, such a loss to the world and ceramic community. Please never take his videos down. Thank you for the follow up.

[@swayzevsnorris]

Do you have any documentation \ pdfs of your course? This is great stuff. I’ll recommend these to all the potters I know in Washington

[@sandracartica4932]

All of these videos have invaluable information! I am so grateful to have access to this college-level learning. Thank you so very much. I hope to visit the studio once I am settled into my new home in Greeneville, TN... it's only a 3 hour drive. 🤩

[@WashingtonStreetStudios]

Sandra Cartica, Let me know when you are coming, we look forward to meeting you! I live 40 minutes from the studio and I will be happy to meet you there!

[@Vsmithpots]

Thanks for these videos, I wish I were closer to visit in person.

[@WashingtonStreetStudios]

We'll be here for a while, let us know if you ever travel this way!

[@kaziebent1686]

Thankyou so much for your extremely informative and thorough tutorials. I have learnt lots!

[@WashingtonStreetStudios]

Thank you for the encouragement, I hope you enjoy all the videos!

[@范姜-d1q]

Thanks!! Ture expert!!

[@WashingtonStreetStudios]

Glad it helped!

[@daviedooog]

Wow thank you, so helpful

[@WashingtonStreetStudios]

You are so welcome!

[@michellemooney1460]

Love love love this info! Pure gold for me!

[@WashingtonStreetStudios]

Great Michelle, glad you are enjoying the channel. Please share our channel with your friends and fellow potters to help us grow our community. Thank you for taking the time to comment.

[@freddiemoretti8456]

Very helpful, even with understanding what may be happening with brush on commercial glazes such as Oatmeal which tends to be as thick as porridge. First change will be to mix it with the electric mixer instead of by stirring. Cosmic Tea Dust gets a lot of attention from folk. Thanks again, cheers and stay well...Freddie.

[@WashingtonStreetStudios]

Freddie, again, we are happy that you are finding these videos helpful. If there is every a topic you would like addressed, just let us know!

[@jabeenirfan8218]

Excellent info.

[@WashingtonStreetStudios]

Awesome, we are happy the information is useful to you!

[@catelesco]

Could you mention what LEAD did for glazes, some of my favorite glaze colors had lead what would I use to replace it.?

[@WashingtonStreetStudios]

Lead is a flux and creates a translucent shiny surface. There isn't a direct substitute, you will have to test fluxes within your glaze recipe. Boron is a candidate. Unfortunately, Phil passed away last July and he was the real expert!

[@VFXited]

The initial handout of common glaze ingredients is missing continuing from the last video. Then from 41:05 (so just after “Original Randis Red Base cone 6” in the handout) to 46:10 (just before the “basic cone 10 ash glaze” in the handout), the notes inbetween are missing from the downloadable version, making it hard to follow from this point onwards. Could the handout be updated if possible please. The teaching is first class, thanks for these fantastic videos!!! :-)

[@WashingtonStreetStudios]

Sorry CW. We have been told about the handouts and I haven't found the correct set yet. I'll let you know when they are corrected.

[@Workuj]

Thank you a lot that was of great help to me🙏

[@WashingtonStreetStudios]

Worku Janka, Thank you for the encouragement, please share the channel with your friends and fellow potters to help us grow our community and keep watching!

[@larrylass4268]

I found recipes and notes after viewing video. It would have been wonderful to have a link reminder as to their location in the video. I use a Tenmoku as a base glaze on a porcelain clay and fired cone 10 in an electric kiln. Various colorants are added so I have a range in colors. The glaze has variability so pieces are not identical (a desired look) and provides quality results with few flaws. Thank you for the video. It showed me why and how the components of Tenmoku glaze work together and what can be substituted if necessary.

[@WashingtonStreetStudios]

I have a link buried in the description and I will try to find a better way. Thanks for the comment and glad the video was useful!

[@matheusmachadoalfradique6151]

@@WashingtonStreetStudios Can't you just add the link to the handout pdf on the first line of the description?

[@glendaneaton9646]

Is there any way I can find out what additives make what colour when added to a base glaze recipe? Is it possible to do a chapter on this?

[@WashingtonStreetStudios]

Clay and Glazes for the Potter, a book by Daniel Rhodes, is a great resource for colorants. Unfortunately, Phil passed away in July and he was our glaze expert. I am not as camera savvy, but I will work up a presentation and this topic is as good as any to start with! Thanks for the comment.

[@glendaneaton9646]

@@WashingtonStreetStudios I am so sorry to hear this.His videos have made glazes start to make sense. Most just say “do this” without any explanation.

[@Queensthief195]

@@glendaneaton9646 oh no, I'm so sorry. I'm enjoying his presentation so much! I feel I'm starting to know him. That's so sad. Thank you for sharing his videos with us

[@rickwise6259]

Question: if you have a glaze that settles out quickly, is it OK to add some bentonite, say 2%, even though it is not part of the recipe?

[@WashingtonStreetStudios]

If the recipe doesn't already have bentonite, they yes, that is the best way to reduce settling! If there is nepheline syenite or any sodium based ingredient in the glaze the problem could be deflocculation. Try the bentonite first, it will help, and you may still have to flocculate the glaze by adding an epsom salt solution. Great question!

[@salvaterrapottery]

I have learned tons from you already! Thanks so much. Problem I am hoping you can help with. I have a glaze I’ve consistantly used for years with great results. It has 5 percent titanium which gives me a nice white. When I tried this glaze with a glaze fountain it is streaky and goes yellow. Why do you think this is the case? Settling of the titanium to the bottom? Need to flocculate? Thought you might have a better understanding of the qualities of titanium and application. Thanks, Sue

[@WashingtonStreetStudios]

Sue, can you post the recipe or send it to [e-mail] and we will take a look? Only knowing one ingredient isn't sufficient to analyze a glaze. Great question though and it will be fun to see if Phil can figure it out!

[@salvaterrapottery]

@@WashingtonStreetStudios Thank you so much for responding so quickly. Here is the formula: Cone 6 Feldspar EU 20 Frit 3134 20 Wollastonite 15 EPK 20 Talc 6 Silica 19 5% Titanium Let me know what you think. Thank you again. And if you are ever in the Asheville area I hope you will stop by our studio!

[@WashingtonStreetStudios]

Sue, Thanks for watching our videos and for your question! Sorry for the delay in responding - had to think about this one. Without seeing the fired glaze and the fountain in action, it’s hard to speculate, but the only two causes that I can think of are either contamination from the fountain or separation/segregation of the glaze ingredients. For example, it wouldn’t take much iron to create yellowish streaks. Have you used other glazes with the fountain and seen any similar strange effects? Depending on the spray pattern of the fountain, it’s possible that the fountain is causing the ingredients to separate when they hit the clay surface. It would probably be a good idea to flocculate the glaze (Epsom salt solution) and see if that helps. Phil

[@salvaterrapottery]

Thanks Phil. I was also thinking maybe we weren’t getting the glaze completely mixed up and maybe we were getting extra titanium. I’m using a sump pump so it is drawing from the bottom. I’ll try a few things and let you know what the results are. Appreciate the response.

[@glendaneaton9646]

Is it possible to post the handouts or copies of some of the things referred to?

[@glendaneaton9646]

Found them, thanks

[@WashingtonStreetStudios]

Yes

[@WashingtonStreetStudios]

Awesome!

[@Kornol66]

Question: There is one thing in glaze chemistry that baffles me. It concerns calcium, CaO, that we often source from ingredients like whiting, dolomite or wollastonite. What we want is the CaO, so why do we not use it directly? Sourced fom calcined sea shells for instance, which is coincidentially sometimes used for wadding in wood firings - so there should be ample supply, at least to a substantial portion of the potters. I feel like there is some important information that I am not aware of, staring me in the eye.

[@WashingtonStreetStudios]

Good question, I have forwarded your question to Phil and I will post his response. Thank you for watching!

[@WashingtonStreetStudios]

Thanks for your question. The problem with calcium oxide is that it’s not stable. It tends to absorb water and change into calcium hydroxide or absorb carbon dioxide and change back into calcium carbonate. So left exposed, you couldn’t be sure what the composition was. Since most sea shells are mostly made of calcium carbonate (some are calcium phosphate), you could just grind up the sea shells and use them instead of the normal whiting (they would contain some additional impurities). In fact, a lot of the limestone that is mined and sold as whiting was originally produced by tiny sea creatures; their calcium carbonate skeletons/shells settled to the bottom of the ocean, creating the limestone deposits. Phil

[@Kornol66]

@@WashingtonStreetStudios thank you kindly for the explanation, it is very kind and helpful.

[@zahramahmoud7640]

الجليز انواع ومراحل وانواع الحريق ومراحله من اسرار خبير الفخار وعلمه

[@WashingtonStreetStudios]

Thanks for sharing!