Freya Posted January 30 Report Share Posted January 30 Hello, I am new to this community and to pottery/ceramic topic and I really appreciate if anyone could help answer my question. I recently purchased a Sri Lanka teapot from Studio M, a brand from Marumitsu Poterie, Japan(https://www.marumitsu.jp/webstore/srilanka-l2395/?sl=en) And it’s purposefully made so that it looks a used ceramic teapot. So on their website, it’s mentioned that the glaze color is supposed to have strong irregularity. However, I found it odd to see those glossy spot/speckles on the semi-matte finish. Does anyone know what has caused those metallic, shiny, glossy greyish spot out of the supposed white-yellowish-brownish glaze? Thanks in advance and really appreciate your help! Quote Link to comment Share on other sites More sharing options...
Freya Posted January 30 Author Report Share Posted January 30 Those spots are also found inside the teapot and somewhere on the body and it doesn’t look like simple scratches. Quote Link to comment Share on other sites More sharing options...
Callie Beller Diesel Posted January 30 Report Share Posted January 30 It looks like it’s a mineral of some kind (likely iron) bleeding through the glaze from the clay body. It’s quite common in stoneware clay of any kind. Nothing out of the ordinary at all. Rae Reich, Roberta12 and Hyn Patty 3 Quote Link to comment Share on other sites More sharing options...
Freya Posted January 30 Author Report Share Posted January 30 Thanks @Callie Beller Diesel! Yeah I am an absolute newbie in this area and really appreciate your inputs! So I can safely assume it is still food safe? I was under the impression that an intact glaze is critical in ensuring the pottery is food safe because the glaze is working as a shield to separate all toxic chemicals inside such as lead paint etc. Quote Link to comment Share on other sites More sharing options...
Callie Beller Diesel Posted February 1 Report Share Posted February 1 Your new teapot is unlikely to cause you any harm, short of breaking it and cutting yourself on a shard accidentally. It doesn’t have any warnings about lead or cadmium, nor do I see any colours or textures in that line of work that would lead me to suspect any use of those materials. If you’re super nervous about anything and want some reassurance, you can get lead test kits for pottery on the ‘zon, but I’d be surprised if this item came back positive. In the product description from your link, where it says Material Icon, there’s a number of little care instruction and definition buttons. When you click on “Iron in Powder” (likely a translation vagary) it points out that there may be some dark specks that appear in the final piece from iron impurities in the clay. There’s going to be considerably less iron that could possibly come out of this teapot than, say, a cast iron frying pan. Glaze doesn’t work the way you’re describing, no. Whoever gave you that description may have been thinking of earthenware that was painted with some kind of lead bearing decorative slip or underglaze, but even that has some dubious underlying assumptions. First, not all pottery is made in the same way. Without getting overly technical, different kinds of clay that people use in different parts of the world will have different levels of porosity, firing temperatures, and a bunch of other stuff. So items made in Japan won’t use the same techniques or materials that get used in, Mexico, or the US, or even Canada. And studio pottery will not be made with the same materials/techniques as industrially produced items. But in general, glaze is used on a clay body to make it stronger, and to make it more waterproof and easier to clean than just the clay surface would be alone. Also, it makes it pretty! ****IF**** a piece of pottery were to contain lead or cadmium, it won’t be in the clay body. Those metals will typically be present either in an underglaze decoration (they make pretty reds, yellows, oranges and some greens), in some forms of china paint decoration, or in the glaze itself. It’s important to note that a lead free clear over a lead or cadmium bearing underglaze **might** not block all lead bleed through should those materials be present. It’s also important to remember that not all yellow/red/orange/green underglazes or glazes will have any of those things in them. There’s lots of ways to get those colours that don’t involve those metals, and are safe for daily use. Hulk, Hyn Patty and GEP 3 Quote Link to comment Share on other sites More sharing options...
Freya Posted February 1 Author Report Share Posted February 1 Wow, thank you so much for all those information and knowledge sharing! It’s so impressive and I have learnt a loooot! I just developed interests with the whole ceramic, pottery study and I wish I could join your pottery studio, learn more and one day become as knowledgeable and experienced as you! I am located in Bay Area, CA though, if you or anyone who visits this post happen to know any good pottery studio based in Bay Area, please let me know. Thanks in advance! Quote Link to comment Share on other sites More sharing options...
Hulk Posted February 1 Report Share Posted February 1 I got a start at local Junior College ceramic lab (Wheel i & Wheel ii), where I enjoyed great access (many "open lab" hours), lots of material and equipment; met many potters from beginner to highly skilled; saw lots of pots; and liked the instructors and lab techs. It was dusty and I didn't always like the music selections, heh, minor complaints. ...hard to beat the price, best deal going! There are also many Studios in the City not affiliated with public education. Perhaps someone in the Bay Area can make a recommendation ...meanwhile, my suggestion would be to find and cruise - talk to the students/members. Quote Link to comment Share on other sites More sharing options...
Freya Posted February 1 Author Report Share Posted February 1 @HulkThank you so much for the inputs! I will definitely do some exploration on the public education resources in Bay Area. Hulk 1 Quote Link to comment Share on other sites More sharing options...
PeterH Posted February 2 Report Share Posted February 2 16 hours ago, Freya said: @HulkThank you so much for the inputs! I will definitely do some exploration on the public education resources in Bay Area. +1 There are also some very useful sites on the web, e.g. https://digitalfire.com Just picking up on your reference to lead (and I agree it's best not used). "Safe" a somewhat conditional term. - The magnificent lead-glazed wall tiles that were still around in older buildings in the 60's would still - IMHO- be quite safe. (Hard to misuse on a dry vertical surface subject to minimal contact.) - OTOH I remember reading of a lead glazed milk jug (which was probably quite safe to use for milk). But the owners squeezed orange juice into it every evening and left it in the fridge overnight to serve with breakfast! Definitely risky. But how do you know what your friends/customers are going to do with your pots? Some craft potters choose to use "liner" glazes for surfaces likely to come into contact with food. https://digitalfire.com/glossary/liner+glaze Liner-glazing is a very good way to assure that your ware has a durable and leach resistant surface. It also signals customers that you care about this. https://digitalfire.com/glossary/lead+in+ceramic+glazes Lead is a melter in ceramic glazes and performs exceptionally well and must be misused to be toxic. It is also now environmentally pervasive. It is toxic and cumulative at any level of exposure. ... and had a history of frequent misuse, hence the [slightly over] reaction to its use. Hulk 1 Quote Link to comment Share on other sites More sharing options...
Freya Posted February 2 Author Report Share Posted February 2 (edited) Thank you very much @PeterH for sharing your insights! Yeah, I like good looking dinnerwares and mugs but I am very worried that I introduce unnecessary risk to my health due to all those not so food safe paints and decorations and glaze…So now I am trying to learn more to ensure that I am getting pretty yet safe products. Edited February 2 by Freya Quote Link to comment Share on other sites More sharing options...
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