How to Calculate specific gravity in your Glaze (ft. Sue McLeod)

#art #pottery #gravity
hello potter's, in this video we will be discussing the all-important specific gravity. this is something that is very necessary if you ever plan on mastering making your glazes as it is extremely important concerning the ratio of water vs glaze minerals.
so in this video I will be teaching you how to calculate specific gravity and teaching you about its importance with a couple of examples along with Sue Mcleod.
big shout out to sue for helping me with this KZbin video, if you would like to see some of her work or sign up for her glaze chemistry classes the links are all right here.
***sue links: Here are some links:
- Online Course - Mastering Glaze Consistency suemcleodceramics.com/masteri...
- Facebook Group - Understanding Glazes with Sue / understandingglazes
- Instagram - Sue McLeod Ceramics / suemcleodceramics
***now all the Donte links!
** My website ( where you can buy my work and frolic around)
www.earthnationceramics.com
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** Music by : Zelda Song of Storms Lofi Hip Hop Remix
• Zelda ▸ Song of Storms...

[@callieclarkwiren1289]

Hydrometers don’t work because they are for measuring SOLUTIONS, not SUSPENSIONS. These are different things in chemistry. Glazes are suspensions, so we are stuck with the old school graduates cylinder method. Hope this helps.

[@BasilWallace]

Before anyone starts with hydrometers, they're not amazingly accurate because you can whip air into the glaze and that will give you an incorrect reading. Use them if you want Personally I use a 100ml plastic tip syringe. 0 it out on the scale, pump a couple times into the glaze to get the air bubbles out, fill it up to 100 and measure. 100 is a good number because you can take your reading (say, 137g) and know without a calculator that's 1.37S.G.

[@Culky]

I've taken Sue's class and it was pretty awesome and comprehensive. And you should totally create your own commercial glazes under the brand "Magical Potter Juice".

[@EarthNationCeramics]

I've got a couple recipes on glazy but you know what. That's a good name. I just might do that if Amoco likes me enough

[@natalielobo]

Just wanting to say...thanks so much. Hands down...this is my favourite pottery channel on KZbin. Love your humour, your information, and how you teach! Thanks for bringing in Sue...she has given me the confidence to try mixing my own glazes and yes, they have turned out great. Keep up the good work!

[@Handmadebygas]

This is awesome information. Thank you to you both.

[@mattntami]

I always learn so much and enjoy your humor.

[@susanvalleauderby2934]

great video - I have taken Sue's course as well, and checking SG has changed my glaze consistency and my confidence. Thanks for this collaboration and spreading the word about the importance of knowing the specific gravity, and for encouraging your followers. Sue is really a great teacher!

[@sashalute935]

Thanks for this video!

[@anafurze9902]

Love the explanation.

[@chellegriggs]

This is an awesome video...and I'm just beginning...wow mind blowing

[@therestlessknitter4290]

Just here to say that the blue version of Randy’s red is still really beautiful, especially where it breaks red. Knowing you can modify the result just by adding water also makes for a versatile glaze.

[@sjmonroe3297]

Officially one of my favorite videos. SCIENCE ART

[@barbsnyder6532]

Wanted to thank you for showing this method of determining specific gravity of glazes. For a couple reasons. One being the cost of a hydrometer, the fragility of a hydrometer (see one), and the accuracy of a hydrometer as someone posted.

[@sisterrosette13]

Thank you. Thank you. Thank you. I’ve been trying to ‘get this down’ for a long time now.

[@lakenpottery8355]

Great video!

[@michaelnied6792]

I was getting crappy results ....... Soooo, I followed you advice ended up having to remove about 4 cups of water from each of my glazes. The next kiln load was much better! Thanks for the tip!!! (You don't need a graduated cylinder, a simple measuring cup that indicates ml works fine)

[@lindalee945]

Thank you for saving me 15$

[@pollyannwhite5343]

Thank you so much for these recommendations. I have made copious notes by stop/starting your video. And gosh, you speak very quickly. Polly Ann White from England

[@movingforward4623]

Spot on video! Had to laugh ascyou described me to a T on determining glaze thickness. LOL Am ordering a graduated cylinder now. Also mixed up a batch of Randy's red just this afternoon. Good videos and your humor rocks.

[@Hipsterchick77]

Brilliant

[@DodieAinslie]

Well heck... wish I had watched this like a couple of kiln firings before now... Thanks... now to go and get it right.

[@LambentLark]

My husband just ordered me Burlson's book, The Ceramic Glaze Handbook. I'm bouncing with anticipation. . . . . . My younger self would be horrified at what I get excited about these days.

[@SSn70s]

With a Hydrometer, water is Zero 0 . - I have used them in the past and their ok but weighing is more consistent. Weighing is much easier to read , just all around better. Good video

[@Matriushka87]

Amé tus videos ♡♡♡♡

[@____Ann____]

The thin one could be called Randy's navy 😬. One recipe and two glazes.

[@its-beady-eyes5120]

A turkey baster works great for removing water from the top of a watery glaze that has had time to settle.

[@sarahlanning608]

Song of Storms in the background was distracting me. This was really well explained! Thank you! I do NOT remember anything from college...

[@smadarstrauss8429]

Thanks from Israel!

[@kevinleong4467]

My understanding which is very useful is 1 ml = 1 g of water.

[@juliolmeda5366]

Soooo I’m kinda new to firing my own pieces, and literally like three days ago did my second glaze fire. Everything turned this pretty blue instead of black that the glaze bottle shows. To clarify I did get completely frustrated from painting and just thinned it a little and poured it over my pieces. Opened the And thought maybe the layer was to thick or my kiln didn’t reach temp or like a thousand other reasons. And literally you video appeared to make it all make sense. Lesson learned I should’ve thinned out the brushing glaze more, and test the SP. Thanks for you help and I will retry the fire and see if the results are different.

[@EarthNationCeramics]

Yes, the majority of black glazes are just a combination of a dark deep rich blue and some type of red. So I'm betting that your glaze is just not thick enough or the gravity is off

[@jaycristaudo1688]

do you have a recipe for Ron Roys gloss black that you have posted?

[@cgapeart]

Water is 1 g/mL by definition. I.e. the volume of 1L is defined by weighing out 1000g of water (probably at a specified air presure). Yay metric. So grams/mL is always how you measure s.g.

[@EarthNationCeramics]

true, and also. The real equation in a scientific setting is P substance RD= ----------------------- P reference This is the reason why I mentioned in the video that this equation mostly works for glaze. ( I was trying to get ahead of all the smarty pants) Also The density of the chemicals that we are figuring the specific gravity for are not always the same, this means that you cannot reverse engineer the equation thinking that 400g / 400ml will = SG 1.00 ( So ppl will try to presuppose the amount of milliliters thinking they equate to grams automatically, every glaze is different) The gravity will differ based on the density of the chemicals. I mentioned this for anyone in the comments below who's trying to reverse engineer it thinking it'll work knowing that milliliters and grams are usually equivocable.

[@EarthNationCeramics]

Just to be clear you are technically correct I just don't want anyone thinking that they can just reverse plug in the math and be ok. I appreciate your comment regardless.

[@cgapeart]

@@EarthNationCeramics I feel like you are tangling it more... But I know what you mean. Density is mass per unit volume, s.g. is a ratio against a reference. However, the default reference is water, and water had a convenient density of 1 in g/mL. Unless another reference is specified, water is assumed and density in g/mL is interchangeable with s.g. In any case this is just my engineering brain trying to interfere with my pottery brain. I have to say I might have to try the experiment myself... I rather like that Blue/green/grey combo the came from the 1.1 s.g. version of the recipe.

[@EarthNationCeramics]

This is just a hypothesis based on my experience. But I'm willing to bet since the gravity of water on Earth is always one . If you mixed 400 ml of water with 400 g of EPK The specific gravity would just come out to be whatever the gravity of EPK is. It's just a guess tho. Something I haven't tried yet

[@cgapeart]

@@EarthNationCeramics the trick is the overall volume won't be easy to predict. You would have 800 grams of mix (mass is always conserved), but how much volume would that take up? Some materials would take up the exact amount of volume the dry powder used (with all the air removed), others would have interactions that could push the water molecules further apart or close together. Then you can start playing with charges (floculants and defloculants) which impact how the particles are suspended... S.g. is useful for pottery because it is something easy to measure and reproduce with each mix of glaze components.

[@cre2919]

Thank you for sharing God Bless

[@rowanmacmillan]

how much powder glaze should I buy for dunking mugs say into a bucket? and what size of a bucket? thanks

[@rondacorkhill1654]

Here's a question. I've been reading The Potter's Complete Studio Handbook (pub 2011) and there are recipes for the clay body. Do you use the clay straight from your supplier or do you add any elements to it? Here's one example: Hawthorne bond fire clay 50x; Goldart stoneware; Kentucky ball OM#4; Custer Feldspar (potassium); Flint 200X; and Grog 48/f. I didn't add the percentages of each. Anyway, I'm impatiently waiting on getting in to the closest pottery class. Thanks for any information.

[@EarthNationCeramics]

I do not add extra elements or components to my clay that I buy from my supplier.

[@TheJmh19]

the question I have is there (if you are mixing your own glazes) an average glaze gravity for say mid fire glazes? Example: most glazes call for a gravity between 1.8 and 3.6. or what ever the number is. that way I could start with gravity and work my way back. hope that makes sense

[@carlasmith2105]

Hi Dante, My husband and I moved about 2 years ago to another state. Before we moved I had to pack up all of my glazes and supplies to make the house sellable. Now I'm trying to get my pottery hobby up and running again and I found that all of my glazes had to be rehydrated. I sieved them with distilled water but I'm scared to death that all is for naught because some of them really needed a considerable amount of water. They are all my PC glazes and wondered if Amaco or anyone could give me some insight into what the SG should be on each one of them. I hope this makes sense to you because I'll just quit with pottery before I have to buy them all over again. Any suggestions? Thanks!

[@EarthNationCeramics]

The chemical will naturally separate from the water because they're heavier than the water itself. Are you really have to do is wait a couple of days and the water will usually rest at the top of the suspension of glaze and you can just siphon it off. It's basically how people who make their own voices take water out of their glazes in the first place. We just wait for it to separate

[@eiyumats6218]

Buying a measuring cup in a kitchen section might be cheaper... $1.

[@jamesewins1125]

Then control viscosity?

[@natashanewman2296]

Look at that fresh cut!

[@cindychiupka-jozin1532]

DOH! I use my hydrometer in a graduated cylinder... oh man where has this video been ?!!!

[@teratheexplorer]

what do you mean *glaze isn't a magical potter juice* _OF COURSE IT IS MAGICAL_

[@robw1571]

Using 100 ml is so much easier. Just take the grams of the 100 ml of glaze and move the decimal place over one and you're done.

[@TheJmh19]

does anyone know? when testing a glaze do most potters start with 100 gram batches?

[@lindalee945]

Yes, and they use sample tiles. I don't. I always do 1000grams which will cover several small to medium pots.

[@kevinleong4467]

1 gram = 1 ml so how do you divide grams by ml?

[@EarthNationCeramics]

You add the grams of the material by the milliliters of the water in a cylinder and then divide them by how many milliliters you put in the cylinder. You're not going to add 1g + 1ml and then divide them by 1 and expect it to make one .

[@natashanewman2296]

Glad you went over this, stank you

[@wallylasd]

Brainy smurf says to use a hydrometer and use the lower part of the meniscus as your reading before having a Greek wedding.

[@EarthNationCeramics]

Anyone is welcome to do it anyway they wish. As long as they stay consistent. Don't switch back and forth and make sure you keep notes. 🏺

[@abs0lute-zer061]

This is just density?!

[@nickagriesti6708]

Ok but, like, how did you get formal training in the field and not encounter the concept of standardizing your glaze calculations?

[@EarthNationCeramics]

I got these things called books

[@Ulujmf]

Not even sure what she is talking about. So many people call themself expert without being one. Specific gravity is the ratio of the density of a substance to the density of liquid water in this case. Can be solid or gas. So in short more water and the density will be lower. That's s all.

[@carsonpog480]

Ehh, i just use a hydrometer

[@gabriellegibby3293]

16:18

[@carsonpog480]

@@gabriellegibby3293 ‘‘twas a joke

[@lb003g0676]

Just use a hydrometer, Donte. On an unrelated note I don't have the time to watch videos over 16 minutes long.

[@EarthNationCeramics]

But you do have time to make an unrelated comment, clearly.🤡 Also if you would have watched it all the way you would have heard the reasons why or why not you might want to use this method over a hydrometer. I give you examples of textiles and two different gravities, I brought on a teacher that specializes in this type of thing and give you an actual representation of how to do it along with reasons why you wouldn't want to use hydrometer and why you would all under 16 minutes. You damn near received a full-on class under 16 minutes. If you don't have patience to learn something like this in under 20 min you probably don't have the patience necessary for this art form. Uninstall, kid.

[@lb003g0676]

@@EarthNationCeramics I tried to make a joke, but obiously it didn't land. I think the time stamp where he said people will tell him to use a hydrometer was like 16:15 so I made the joke about 16 minutes, nvm!

[@lb003g0676]

@@EarthNationCeramics Oh shit, it's actually you. Hi.

[@EarthNationCeramics]

I live. And I see everything 🤖

[@EarthNationCeramics]

Sorry about that. I get so many of these comments in earnest that I'm just tired of them now (partly why I mentioned it in so many videos)