Hi ! Doing it that way you loose the precision of 0.01 g brought by you scales. Because you loose some of the two first products : in the cup (soda ash) & in the bowl (sodium silicate) ! But, if you weigh your ball clay 750 g instead of 750,00 g and mesure the water by its volume & not by its weight (with the same precision of 0.001g) your mix will be wrong anyway !! So, if you really need to be truly precise, this is how it's done in laboratories : (Note : You can use this method for all mixes with solvant(s) - which is water, in that case.) Containers : > You must have 3-4 recipients for your water : 1 to hold it, easy to manipulate - it could even be 2 bottles, for easier handling) ; 1 with your hot water (the bowl you have is ok ; 1 to make your mix (the large jar you use is ok ; but when you begin it must be empty.) > For the soda ash : You can keep this cup of yours. > For the sodium silicate : Use the same cup. > For the ball clay : 1 bowl if you weigh it in advance /or in the bowl used for the hot water, if you weigh it after the mixing of the 2 other products. (In that case, the bowl must be large enough to put the clay /or you can weigh it twice, but don't forget to tare it each time.) Modus operandi : Use the cup to mesure the soda ash but DON'T PUT IT in the hotwater bowl ! Put a smal quantity of this water IN THE CUP ; mix it (with a stick or a spoon) & put in your large jar ; then rinse the interior of the cup & the spoon with the rest of the hot water (into the jar) once or seveval times (even better) - no need to rinse the exterior of the cup if clean & dry ; shake the jar if the ash hasn't fully desolve (you don't need something else to mix at this stage. Made that way you didn't loose any product yet... Sodium silicate : Tare your cup on the scale (you need to tare it again because with the precision you said you need (0.01 g), the few drops of water left in the cup do count !) ; then mesure your dose of sodium silicate ; then, verse some of your cold water (from the 1st bottle) in the cup & mix it (with the same stick or spoon you used for the ash) ; verse in the jar & rinse abondantly cup & tool ; agitate firmly the jar closed (don't need you mixer yet !) ; open it & rinse the lid (in the jar) with a little of water from the second bottle or saved from the first. Ball clay : My opinion is that the fewer dishes you have, the better it is - then tare the bowl used for hot water, & weigh the clay ; put it in the jar ; rinse the bowl & the spoon with the 2nd bottle (save a little to rinse the lid) ; shake with the lid, rinse it ; now you can use your mixer because all your ingredients are in the jar & mixed. Even if you loose some of the mix on the mixer, this will make vary the quantity (very small volume) but not the composition (%) !! Specific gravity : Note that the first method is the easier one but you must have an hydrometer (a reliable & suitable one for this use) ; for the 2nd method you must know how to appreciate the meniscus of a liquid in the graduated cylinder : 1/ You must have the cylinder on a stable horizontal surface. 2/ The meniscus is the little plate, with curving up edge where it touches the wall of the cylinder, formed by the surface of the liquide. 3/ You take the mesure on the lower & flat part of the meniscus (the surface, not the ring : curling edge). Place your eyes truly horizontaly to the surface of the liquide - In the right position you see just a line : It indicates the mesure to read, or the volume you have to reach : 100 ml (don't forget to tare the cylinder !) - I have to say that your cylinder must be of quality if you want a reliable mesure. Usualy the glass ones are better than the plastic ones. I hope this will be helpfull to someone... ;·) (Please excuse my heavy writing style, I'm French !)
Thank you very much for the video!! Can you tell do you use high temperature ball clay, oh low temperature clay? And at what temperature (cone) do you fire a product coated with Terra Sigillata? What kind of clay - high-temperature or low-temperature do you use as a shard under Terra Sigillata?
I made burnished smoke fired pots on a pottery course 30 years ago and am wondering if this the right thing to apply to leather hard items to burnish for pit firing?
Hi Marcos, I'm glad you liked the video. With my work, I tend to just sell locally and as such, don't show it online. I'm thinking of making a site to show it though. When I do I will let you know. Thanks again for watching!
@@ThePotteryWheel Thanks for replying. Before I read your response I looked into it and I thought it may be because I let it sit for a few days, and so I added more water, mixed and weighed again until I got it back to 112g. I'll now leave it for 24hrs then reduce and hopefully that will work?? Thanks again!
Natron containing clays burn at very low temps. So it is a low heat agent to reduce burning temp for the glace, in result the glaze will become liquid at a temp under 500°C. Check for Geopolymer. The recipe is almost identical. When the recipe is adjusted perfectly you can harden Geopolymers at 60°C in a oven and they will become stonehard.
Why make it harder then it is? Try the same recipe and then adjust the water content until you are happy with the result. At the end the glaze has to cover the clay you have. Dont make it to thick because then the glaze will become maybe to thick to and get cracks. Thinner glazes are better. When you burn the glaze what happen ? You form a glass and when the glaze is to thick the glass will drip down. Thinner is because of that better. Until you like glassdrops forming as artistic bonus.
I've never put stains in terra sigillata. I know some people do though. I think that there can be issues with the granules of stain affecting the terra sig shine a bit. But it might just be something to experiment with. Let me know how it goes :)
Thank you for the explanation. Your method to explain was great and helpful.
Hi !
Doing it that way you loose the precision of 0.01 g brought by you scales. Because you loose some of the two first products : in the cup (soda ash) & in the bowl (sodium silicate) ! But, if you weigh your ball clay 750 g instead of 750,00 g and mesure the water by its volume & not by its weight (with the same precision of 0.001g) your mix will be wrong anyway !! So, if you really need to be truly precise, this is how it's done in laboratories : (Note : You can use this method for all mixes with solvant(s) - which is water, in that case.)
Containers :
> You must have 3-4 recipients for your water : 1 to hold it, easy to manipulate - it could even be 2 bottles, for easier handling) ; 1 with your hot water (the bowl you have is ok ; 1 to make your mix (the large jar you use is ok ; but when you begin it must be empty.)
> For the soda ash : You can keep this cup of yours.
> For the sodium silicate : Use the same cup.
> For the ball clay : 1 bowl if you weigh it in advance /or in the bowl used for the hot water, if you weigh it after the mixing of the 2 other products. (In that case, the bowl must be large enough to put the clay /or you can weigh it twice, but don't forget to tare it each time.)
Modus operandi :
Use the cup to mesure the soda ash but DON'T PUT IT in the hotwater bowl ! Put a smal quantity of this water IN THE CUP ; mix it (with a stick or a spoon) & put in your large jar ; then rinse the interior of the cup & the spoon with the rest of the hot water (into the jar) once or seveval times (even better) - no need to rinse the exterior of the cup if clean & dry ; shake the jar if the ash hasn't fully desolve (you don't need something else to mix at this stage. Made that way you didn't loose any product yet...
Sodium silicate : Tare your cup on the scale (you need to tare it again because with the precision you said you need (0.01 g), the few drops of water left in the cup do count !) ; then mesure your dose of sodium silicate ; then, verse some of your cold water (from the 1st bottle) in the cup & mix it (with the same stick or spoon you used for the ash) ; verse in the jar & rinse abondantly cup & tool ; agitate firmly the jar closed (don't need you mixer yet !) ; open it & rinse the lid (in the jar) with a little of water from the second bottle or saved from the first.
Ball clay : My opinion is that the fewer dishes you have, the better it is - then tare the bowl used for hot water, & weigh the clay ; put it in the jar ; rinse the bowl & the spoon with the 2nd bottle (save a little to rinse the lid) ; shake with the lid, rinse it ; now you can use your mixer because all your ingredients are in the jar & mixed. Even if you loose some of the mix on the mixer, this will make vary the quantity (very small volume) but not the composition (%) !!
Specific gravity : Note that the first method is the easier one but you must have an hydrometer (a reliable & suitable one for this use) ; for the 2nd method you must know how to appreciate the meniscus of a liquid in the graduated cylinder : 1/ You must have the cylinder on a stable horizontal surface. 2/ The meniscus is the little plate, with curving up edge where it touches the wall of the cylinder, formed by the surface of the liquide. 3/ You take the mesure on the lower & flat part of the meniscus (the surface, not the ring : curling edge). Place your eyes truly horizontaly to the surface of the liquide - In the right position you see just a line : It indicates the mesure to read, or the volume you have to reach : 100 ml (don't forget to tare the cylinder !) - I have to say that your cylinder must be of quality if you want a reliable mesure. Usualy the glass ones are better than the plastic ones.
I hope this will be helpfull to someone... ;·)
(Please excuse my heavy writing style, I'm French !)
Very interesting, thank you. Why does the SG matter? Can you just go by the consistency that you like to work with?
Thank you very much for the video!! Can you tell do you use high temperature ball clay, oh low temperature clay? And at what temperature (cone) do you fire a product coated with Terra Sigillata? What kind of clay - high-temperature or low-temperature do you use as a shard under Terra Sigillata?
hello, I wrote this a while ago, I think it will answer your questions, if not let me know :-)
Awesome video thanks for sharing
very good work , this was very informal , greeting from egypt
I made burnished smoke fired pots on a pottery course 30 years ago and am wondering if this the right thing to apply to leather hard items to burnish for pit firing?
you can burnish or use terra sigillata, both work well with pit firing
Great video! Where can I see your work?
Hi Marcos, I'm glad you liked the video. With my work, I tend to just sell locally and as such, don't show it online. I'm thinking of making a site to show it though. When I do I will let you know. Thanks again for watching!
Hi, I did it , awesome !!! Thanks so much 😊🙋🏼
Hi, very helpful video. I've measured the weight after leaving to settle but before reducing and I've got 118g. How would I rectify this?
Hi there, I'm glad you found it helpful. If 100ml weighs 118g, then I don't think you need to reduce it. I should be fine as it is.
@@ThePotteryWheel Thanks for replying. Before I read your response I looked into it and I thought it may be because I let it sit for a few days, and so I added more water, mixed and weighed again until I got it back to 112g. I'll now leave it for 24hrs then reduce and hopefully that will work?? Thanks again!
@@benlewis6 Yes, that will work fine... good luck :)
thanks
1. how do i know the SG for making TSG of my clay ?
2. what for is the soda ash ?
Natron containing clays burn at very low temps. So it is a low heat agent to reduce burning temp for the glace, in result the glaze will become liquid at a temp under 500°C.
Check for Geopolymer.
The recipe is almost identical.
When the recipe is adjusted perfectly you can harden Geopolymers at 60°C in a oven and they will become stonehard.
Why make it harder then it is? Try the same recipe and then adjust the water content until you are happy with the result. At the end the glaze has to cover the clay you have. Dont make it to thick because then the glaze will become maybe to thick to and get cracks. Thinner glazes are better. When you burn the glaze what happen ? You form a glass and when the glaze is to thick the glass will drip down. Thinner is because of that better. Until you like glassdrops forming as artistic bonus.
Fascinating, thank you!
Thank you, I'm glad you found it interesting!
Hi, how much of ball clay?
Is it for low fire or high fire?
both...ancient people don't have high fire kiln, so the terra sigillata is used to seal their pot instead of using glaze, so it is safe for cooking.
🥰🥰👏👏👏
Can you color terra Sig with mason stains?
I've never put stains in terra sigillata. I know some people do though. I think that there can be issues with the granules of stain affecting the terra sig shine a bit. But it might just be something to experiment with. Let me know how it goes :)
Just like the Greeks did it