Understanding Pottery: Chapter 1 What is Clay?
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- เผยแพร่เมื่อ 3 เม.ย. 2020
- Thank you for watching our video on What is Clay?
Understanding Pottery is a video series in production by Washington Street Studios. The video series is a digital textbook that will take the viewer through the entire ceramic process from the raw material through the finished ceramic pieces. This is chapter one: What is Clay?
Have you ever wondered what makes up this material we use to make pots? Are you planning to create your own clay recipe? Learn the fundamental ingredients needed to make a clay useful in the ceramic arts.
The next video topic in the Understanding Pottery series will be Clay Properties and Drying.
This video is brought to you by Washington Street Studios, a community pottery studio, gallery and pottery school located in Harpers Ferry / Bolivar, WV. We exist to provide ceramic artists an affordable, fully equipped studio space for aspiring, emerging and established artists to share their creative energy and knowledge in an environment designed to support the ceramic artist. If you want to learn more about Washington Street Studios, visit our website at www.hfclay.com/.
At Washington Street Studios, we believe the sharing of creative energy and knowledge will improve the quality of our art and increase the appreciation of art within our community. We are striving to create an environment where the arts are shared and appreciated. We want to grow as a family of artists and contribute to our community. This channel is one of our steps to share our passion for the ceramic arts, creative energy and knowledge with other artists and art lovers
We also created a podcast to expand our audience. If you are looking for an audio version of our show search for ‘The Potters Round Table’ on your favorite podcast platform of choice.
My favorite special tool sources:
Bill van Gilder Pottery: www.vangilderpottery.com/onli...
Troy Bungart: troybungartstudios.com/
StudioPro: studioprobats.com/
Channels of interest to potters:
Bill van Gilder: / vangilderpottery
Jonthepotter: / @jonthepotter
Ceramic Jim: / @ceramicjim
John Britt: / @johnbrittpottery
Earth Nation Ceramics: / @earthnationceramics
Simon Leach: / @sleachpots
Bill Powell: / bpartnd
Ingleton Pottery: / youdanxxx
Hsinchuen Lin: / hsinchuen
Ron Philbeck: / ronphilbeckpottery
Collin Shadwell: / @collinshadwell
I'm an amateur in ceramics, and was looking for lessons which explained everything about it in a clear and structured way. Thank you for your valuable videos - they are a real treasure for me!
Welcome to the ceramics community! This series will help you avoid many mistakes we make as beginners. You might consider chapters 1-6, 9, 18, 19, 20 and 25 to get a good basis for making and glazing pottery to have the best chance for success. If you have your own kiln then you may want to include the appropriate kilns and firings chapter, like chapter 15 on electric kilns. Then you can go back to any chapters you have missed. All of the topics are standalone so you can watch them in any order. And if you have any questions, feel free to ask! We are happy to help. Also, please share our library with your friends and fellow potters! And thank you for the encouragement and kind words.
Wow thank you for explaining this! For the first time I am not confused! You are truly a wealth of information! Please keep making videos!🥰
Thanks Janette! We have over 20 videos planned for the Understanding Pottery series. It will go from raw clay to finished pots. Subscribe to the channel so you are notified when the new videos are available and thanks for watching!
I'm so excited to find this series. I'll be watching these lectures in full.
Mallory, hope you enjoy the videos, please share the channel with your friends and fellow potters!
Thanks Phil. I find your presentation interesting, clear and to the point. I have just signed up for a basic membership(currently what I can afford) on your patron channel. 👍
Thanks for being a patron! Together we will make these videos and our podcasts available to artists, educators and potters free of charge.
Thank you so much, I love this series already! Such a helpful way to get a grasp on the basics. Taking many notes and learning a lot!
Roux McG, you are so early in the series and there is so much more coming your way! We hope you enjoy all the videos. Thank you for your support and kind words. Please share the channel with your friends and fellow potters to help us grow our community!
Beautifully presented, as always
Thank you grandcarriage!I
Thank you so much for this series. And thank you for explaining it so clearly that even someone as scientifically challenged as I am can understand it.
Thank you for watching and your encouragement! Please share our channel with your friends or fellow potters to help us grow our community!
Very well explain and so much too learn. I am truly bless by your lecture.
Thank you and GBU
Thank you and I hope you enjoy the entire series!
Informative, down to the point - pure gold! It is ridiculous that I am paying for local courses but only get a potion of information what is being presented in this course. Thank you for sharing, I am grateful to be able to access it.
That makes you the perfect audience! Phil wanted to teach everything you would learn in a BFA/MFA with a focus on ceramics without the actual creation of pottery. Phil taught ceramics at Hood College for years and he wanted to create content for people like me. I have no formal art education and started pottery late in my life. This series really hit the mark! We are happy you are enjoying it, please share it with your friends and fellow potters!
Hi, i'm a graphic designer from Turkey and i decided to start making clay beads for my personal projects when i couldn't find any local sellers. Fell in love with it quickly and now i am trying to get a much better understanding of pottery so that i may some day have my own studio hopefully. I found that i enjoy carving the most but i want to get better at glazing. This series is so amazing and enjoyable that i watch them over and over just to make the knowledge sink in as deeply as it can. Thanks a lot for putting these videos up, you have following from all around the world.
epocaBB, thank you for the kind words and we hope you continue to find the videos useful and interesting! Please share the channel with your friends and fellow potters to help us grow our international community! Your support and encouragement makes all the difference!
This is the most informative and understandable video I've seen on the subject of firing clay. Can't wait to see the rest of your videos! Much appreciated from the clay state of Indiana :)
Thank you Rick! I'm originally from Illinois and currently live in Maryland. I drive through Indiana every time I go home to see family. If you live close to I70 I've probably gone by your house! Thank you for watching, be sure to share the channel with your friends and fellow potters to help us grow our community! And if you have suggestions for future episodes, let us know.
@@WashingtonStreetStudios Wow, very cool! I'm a bit further south of I-70, originally from Nashville. I just may have an idea or two for you to consider, and will have to think on that a bit after I watch the rest of your current uploads. That may be a while though as I must admit, less than have way through your presentation when you starting talking about vitrification, I got so excited I paused the video, grabbed a shovel and went to the back yard to dig up a bucket of beautiful red clay I'd been eyeballing for a couple of years now. In pockets, the clay is so rich and red that it can be rolled up to look like a tiny red worm, then wrapped around the pinky without even any flinch of a rupture. Now I just need to figure out what to do with it. :)
Btw, at 4:00 I was also fascinated to learn that the clay in plates is made of plates in the clay! Try saying that one ten times fast.
But joking aside, I'll have an entirely new outlook from now on whenever I hear the term "clay plates"! :-D
Many thanks again!
🙏Thank you so very much for this series you’re offering. It’s the most useful and informative I’ve found and shall be very happy to support you through Patreon as a recognition for your work. Best wishes from Italy 👋
Daniela, thank you for your comment and for becoming a patron of the show, you are very generous! If you have any questions or comments, please let us know, especially if you have topics for future videos! I hope all is well with you in Italy!
You must be one of the hard working potters at Valley Arts in Oregon.
I'm so glad i found this channel! I bought a small electric test kiln last year, but i've been slowly educating myself before doing anything ignorant and causing a huge mess or destruction to my equipment. Finally, i fired my first pieces this week, glazed with a 50/50 woodash from my pizza oven, and i think i was partly lucky it turned out ok. This feller really helps to fill in SOOOOO many blanks i have about the basics and lays it out in easy to digest monologue. Excellent work!
I hope you enjoy all the videos!
OMG...you are seriously fantastic!!!! Best videos for beginner potters ever.
Thank you Thank You
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Ren Airie, Thank you for your encouragement! Please share the channel with your friends and fellow potters to help us grow our community.
Thank you so much for sharing this wonderful subject with the world.
Dan, you are welcome. Please share the channel with your friends and fellow potters to help us grow our community!
This was an excellent lecture, and it broadened my understanding of this craft of pottery making.
Great, thanks for the encouragement!
Thank you for your work!
It's a pleasure!
This was captivating and thorough.
You, sir, are an excellent teacher.
Thank you very much.
Thank you hhippiittyy, Phil was a good teacher, unfortunately he passed away in July 2021. His legacy is captured in these videos!
THANK YOU!!!!
You're welcome!
I love you! So clear and instructive thank you
Thank you Dalil, please share the channel with your friends and fellow potters to help us grow our channel.
Thank you so much.
Dan Peterson, You are most welcome! If you are just starting the Understanding Pottery series, you are in for a treat. You will experience over 100 videos that cover every topic in a ceramics BFA/MFA program. Enjoy and please share the channel with your friends and fellow potters to help us grow our community.
Very clear and helpful!
Thanks so much
Ralph, we are happy you find the channel useful, please share with your friends and fellow potters to help us grow as a community!
Thank you for sharing your vast knowledge
Phil was a champion and a valued resource. We are fortunate to have captured his knowledge in these videos before he passed.
Wholeheartedly agree with all comments below. What a treasure of information. Thank you so so much
Your welcome.
Thank you for this !
Thanks Alisa, I hope you enjoy all the videos on the channel! And please share the channel with your friends and fellow potters to help us grow our community.
all your videos are just perfect! I learn SO MUCH!!!!
Thank you for the encouragement Karina Campos, please share the channel with your friends and fellow potters to help us grow the community!
Thank you so much for this series. And thank you for explaining it so clearly 😀
You’re welcome, and thank you for watching!
So very very helpful!! I’ve been looking for this information for months. Thank you!
You have many more videos in the series and it should give you a good foundation for everything taught in a BFA program. Enjoy!
Thank you
You are welcome, I hope you enjoy all the videos!
These are really fantastic. Thank you.
Thank you for the encouragement!
Fantastic! Thank you!
Sioned Jones, you have soooo many more videos after this one just to finish the 'Understanding Pottery' series! If you like this one, you will love the rest! Please share our channel with your friends and fellow potters to help us grow our community!
@@WashingtonStreetStudios I'm working my way through them, notebook in hand, This is the Ceramics MA I couldn't afford to do.
This is exactly what i was looking for. Thank you so very much!
The understanding pottery series will take you through all the subjects taught in a typical BFA program. Enjoy the learning and please share the channel with your friends and fellow potters to help us grow our community!
Thank you for this. So valuable and rare to find such crucial information.
Thank you for your encouragement and please share with your friends and fellow potters.
Loving your channel
Thank you for the encouragement!
Thankyou so much for this information
Ahmed, you are most welcome and thank you for your feedback! Please tell your friends and fellow artists about the channel and enjoy the rest of the videos!
this is a wonderfully informative series! thank you tremendously!
Thank you, please share the channel with your friends and fellow potters to help us grow our community.
Excellent discourse, really interesting talk, perfect presentation, and totally the most incredible model clay particle, sooooo delicious!
Best Bites, I hope you go through the entire Understanding Pottery series and enjoy all the videos as much! Please share the channel with your friends and fellow potters to help us grow our community. And than you for watching!
I just clicked on this film because I thought it looked interesting, I know next to nothing about ceramics, pottery or sculpture etc, it was such a fascinating and informative film and the presenters commentary flowed fabulously, I found it very easy to understand and follow, thank you, regards John from sunny Devon UK
Thanks for watching, I hope you enjoy all the videos.
Very nice. Thank you very much.
katiakatiakat, thanks for the encouragement, please share the channel with your friends and fellow potters to help us grow our community.
Thank you very much, greatly appreciate your informative video about clay! It really help me prepare art lessons for my students!
I hope all the videos are as helpful!
Such insightful information and for free! Can't thank you guys enough! Love from India!
Sanchit Sharma, Thanks for the encouragement and enjoy all the videos. Please share the channel to help us grow our online ceramic community!
I was randomly wondering about clay and found way more information than I was expecting! Thanks 🙏
Awesome! The Understanding Pottery series is designed to follow the coursework in an MFA program from start to finish. If there is anything you want to understand about ceramics, you should find it here! Please share the channel with your friends and fellow potters to help us grow our community!
Washington Street Studios Ah gotcha! I actually have no experience with pottery, I’m just a chemistry student and was wondering about the composition of clay. I’ll be sure to share :) Have a wonderful day!
A chemistry background would be very useful for a potter, actually. Did you ever study glazes? Basically it's the controlled melting of glass materials over pottery that was already fired once. This seals the work which aids it in holding liquids. Also adds color and strength. The glazes range from transparent to opaque. Colors are produced either through chemical reactions within the glaze or by using modern pigment additives called mason stains. Underglazes made with these stains are like clay paint. They are excellent for fine artistic decorating. Additionally, the color of the clay body itself can show through and contrast to the glaze.
This topic is utterly fascinating. Same goes for the history of the craft, which is no doubt one of the oldest human technologies associated with organized civilization.
Very informative thank you
I hope you enjoy all the videos and share them with your friends and fellow potters to help us grow our community.
Thank you so much for this series! It is great to get information of such depth and from a real expert (rather that someone who is simply social-media famous, although they can be fun too ;)
Caitlin, I agree with both of your statements. I am so fortunate to have Phil as a business partner, he is wise and happy to share his knowledge!
I also love 'TH-cam University' and I have learned a lot from Simon Leach, Bill van Gilder, Ron Philbeck, John Britt, Collin Shadwell, jonthepotter, Earth Nation Ceramics, Mathew Kelly, there are too many to name! We are pleased to be in a list with any of these artists!
I'm extremely excited about finding you on FB!
Looking forward to all the Tube classes! Taking notes and making pottery a dream come true!
Having already completed my chemistry in college I can actually see how chemical reactions occur and interact.
Pamela Laird, Thank you for the kind words! Phil did a good job of presenting every subject of a BFA / MFA Ceramic Arts program in the Understanding Pottery series. Keep watching and share the channel with your friends and fellow potters to help grow our community!
@@WashingtonStreetStudios I absolutely will share the experience with others and encourage them to watch the "Real" classes before just starting online shopping and thinking it's okay to just throw things together that could possibly blow up something not understanding the "very important chemical compounded!
Wow! What a nice material!!! Love the scientific aspect of pottery, and it's hard to approach it without this kind of material. Thank you so much!
You're welcome
Most of my experience of clay has been at school, where all the technical aspects were taken care of. Since that's my point of reference though, I'd love to know what kind of body/mix that grey school clay would likely have been
Most grey school clays are a general purpose, wide range, stoneware clay, a good example from Standard is Standard 153 white or buff stoneware. We have this in our studio and use it in our classroom.
Greeting from Korea!! Thanks for this very informative video. It was so hard to find pottery theory
I'm glad you enjoyed the videos, keep watching!
Such clear and informative presentations ... I look forward to each one. Your sharing is so appreciated ... Thank you.
Thank you for the encouragement. Phil was a great teacher. He passed away last year and I am so thankful we have captured his legacy in these videos! I hope you enjoy all the content.
This is great! I am a visual artist in my mid sixties and I am just starting with ceramics as a different media to continue with my creativity. I don't have the time to go back to school and I am a self learner anyhow this is exactly what I was looking for! Thank you so much for making it available!!
We hope you enjoy all the videos!
Thank you for this series! I appreciate your content very much. It's extremely helpful for a beginner like me, just the right amount of technical detail to be successful! :-)
You will learn loads from Phil, best teacher I ever knew!
nice!
Thank you Coronabong, hope you enjoy all the videos and share them with your friends!
Fantastic video, using the information for my research of how cells, dna interact with clay
Phil was a great instructor, all of his videos are pure gold for the potter!
Can you share some information about what you are doing?
🤯👌
Thanks, wish I spoke emoji! lol
@@WashingtonStreetStudios listened to the lesson and was blown away by the knowledge.
Another great video, thank you. If I single fire Porcelain, is there less chance of glaze defects such as pinholing than firing, say Stoneware?
Single firing reduces the chance of pinholes since the slow ramp up of heat gives time for the gasses to escape through the glaze layer and the glaze will heal itself at a higher temperature. I'm not sure if the clay makes a difference, but I can check with Phil, he's the real expert. If you want to learn about his background check out the Artbox Interview from last year, it's on of our earliest videos. Thanks for the comment!
Did these presentations ever get translated into text format in a book or pdf or such? Amazing content!
Thanks, we are working on that!
Thank you for this lecture that sets the stage for understanding the science and art of Pottery.
I have several 10lb bags of clay, and no idea what characteristics this clay has. eg. to what cone it should be fired. It's grey, uniformly fine and dries to a light grey-white color. So how can I test it to learn more about its properties (short of taking it in for chemical analysis.
A testing process would help for those who mine their own clay, which I'd like to attempt at some point.
Thank you again for all these videos that you've made available to us who are starting out on the exploration of this vast topic.
Ken Neth, thank you for the encouragement and for watching our videos!
If you have a test kiln the process is not difficult, although it does require multiple firings to determine what cone the clay should be fired to. Start by making a bar(s) of clay four inches long and one inch wide, about 1/4 inch thick. Fire the clay to cone 05/04 (low fire) and suspend the bar between two posts. After firing, look for warpage, bloats or other types of failures. Repeat the process on the same test-bar of clay, increasing the temperature through a series of cones until you see warping or some failure in the clay, or stop when the bar is vitrified. If I were executing the test, my cone series would be 04, 1, 4, 6, 8, 10. This will work with unknown commercial clay or self-mined clay. I would also create a catch tray made from a known clay body to prevent a kiln shelf catastrophe! Admittedly, I have created a bar, bisque fired it to cone 06, and fired it in a ^6 firing over a catch plate. Only once was this a 'low-fire' clay that melted into a puddle. If you only want to confirm the clay can be fired to your normal firing range, you can take this more adventurous approach.
@@WashingtonStreetStudios Excellent. Thank you for the information.
Thank you for this video, it is very helpful😊 In my country we get a lot of clay with high iron (or other metals which I am not sure) content, does metals in the clay play a part as a flux?
Cindy Koh, keep watching the Understanding Pottery series and you will find that Phil covers a ton of material about the roles different chemicals and elements play in the ceramics world. Unfortunately Phil passed away last July, so I can't ask him your question directly. I did search the internet and found that iron oxide is a flux. I checked zinc oxide and it's also a flux. I think you need to search each element or compound independently. Thank you for the question, keep watching, and share the channel with your friends and fellow potters to help us grow our community! What is your country?
@@WashingtonStreetStudios thank you so much for replying. I am so sorry to hear about Phil's passing, the videos and sharing has been very helpful and informative.
I am from Malaysia. I run a small pottery studio here.
Hi Phil, this has been extremely helpful. Would you have a basic recipe for an earthenware clay body?
I've forwarded the request to Phil, we'll get back to you soon!
Unlike stoneware and porcelain clay bodies, terra cotta bodies are fired to a wIde range of densities (porosities) by different potters for different purposes. Recipes for terra cotta clay bodies can thus vary a lot depending on (1) the recommended firing temperature and the desired level of densification (and the choice of fluxes to get there), and (2) whether or not a naturally low-firing red clay is included in the recipe (and how plastic the clay ingredients are). Here are three examples that use the commercial clay Redart or red earthenware as an ingredient:
Cone 04 Red Earthenware: Cedar Heights Redart 71.4
Ball clay 10.7
Silica 10.7
Feldspar 7.2
Helaine Ettinger's Cone 04 Terra Cotta: Cedar Heights Redart 60
Cedar Heights Goldart 15
Fireclay (-30 mesh) 15
Talc 10
Red Earthenware ( Chappell): Red earthenware clay 75
Volcanic ash 20
Talc 5
Examples without a low-firing clay ingredient:
Red Earthenware (Rhodes): Kaolin 25
Ball clay 30
Frit 17
Talc 5
Silica 10
Red iron oxide 3
White Talc Body Cone 06 - 04: Talc 50
Ball clay 40
Neph. Syenite 10
Check out "The Potter's Complete Book of Clay and Glazes" by James Chappell for a good listing of recipes.
I'm wondering if you have insight about my idea to mix in a bit of fine silica sand in with my woodash glaze. I'm just learning, space is limited, so i want to refrain from buying glaze materials from professional dealers. The sand was already quite fine, but i ground it finer in a granite mortar, and i'll do some tests on bisque fails. I'm guessing that the silica will produce a more glassy effect, with the ash acting as a flux and glassifier, and the clay in the glaze will act as the binder....
pizzatopia, If you are talking about sand that you gathered, or purchased, rather than silica mined for a specific purpose, then you must realize you are getting more than just silica. Playground sand or beach sand will contain many other minerals and organic material. I would try it, but keep the expectations low. And let us know how it goes!
@@WashingtonStreetStudios thanks for the reply. It is purchased silica sand from a professional supplier. However, the bag is written in chinese, so I can't really understand the entire label
Thank you alot for the amazing video..
How do eleminate efflorescence in bricks ? please try to share a video on it
thank you again 👏
I've forwarded the question to Phil and will post his response. Thanks for watching!
Hello Saman,
Thank you for your question. Efflorescence in bricks is generally solved by adding (thoroughly mixing) barium carbonate (BaCO3) into the clay. The amount of barium carbonate needed depends upon the concentration of salts that are present in the clay and the water, so testing is a good idea, but it is typically in the range of 1- 2%.
Phil
Hi,i am already watching and trying to learn things from your channel. Am already training since few months.But still i couldn't found good stoneware clay body. I have powder forms from ball clay, kaolin, feldspar, bentonite, silica . Can you help me and suggest good combination for the body ???,finally that can be glazed .
You can search online and find all kinds of clay recipes for various temperatures. Unfortunately Phil passed away last year, he could have helped develop a clay recipe. Best of luck!
I believe I've harvested and processed some light gray ball clay from a stream in NY. Is it possible to mix it with processed common clay to make a workable high fire clay body?
Nvm haha I had not watched the entire video when I had asked. I'm going to test how much my clay shrinks though I believe it absorbed a lot of water. I tried wet and dry processing and I don't fully remember
Chad, no problem, there are also videos on making shrinkage test bars in the pottery shorts series! Good luck and let us know how it goes!
Thank you 🔆is illite (meca ) mineral ؟
Yes, illite is one of the family of clay minerals and it is formed from mica. Great question.
Hi Phil. Would it be possible to harvest clay /soil from a tidal river and use it to make pottery? I came a really sticky dark clay/mud/soil and was wondering could it be used.
Hi! Thanks for your question. You definitely can gather "clay" from a tidal river, but you'll need to test it to make sure that it contains enough actual clay to be suitable for use in pottery. This kind of sticky, dark mud can contain a lot of organic material that makes it seem more clay-like than it really is. So, to start, I would suggest gathering some of the mud, letting it dry out a little so that it can be crudely-shaped into small flat pieces, and then firing it in a kiln (on a piece of regular clay as a tray) to earthenware temperatures to see what it does (does it shrink a lot, how much remains, is it intact, what color is it, does it look like it is starting to melt, etc.). If it doesn't shrink too much, and it still looks like fired clay, then you could begin to work with the raw mud again to see how it could be modified to make it more workable, for example, like adding another kind of clay or granular material such as fine sand or grog to make it less sticky. Also, if the river is tidal, then the clay may contain some salt, so the raw clay might need to be rinsed before it is prepared for use. A little bit of bleach mixed in can help to reduce the smell of the raw clay. If we can help further, let us know. We have another video that should be out before too long, called "Treasures in Your Backyard - Use of Local Materials", which could be useful. Good luck!
Phil
@@WashingtonStreetStudios thanks a million for your clear and detailed answer to my question 👌
I just found your website and hope you are still monitoring for comments. After watching the first lesson and reading several comments, I was wondering what you might recommend as an additive for making white earthenware even more plastic. I am using an extruder and wish to get the low fire white earthen clay to come out in ripples which require high plasticity. I have tried several different clays to no avail including adding water. Do you have any suggestions?
I will forward this to Phil and reply with his response.
@@WashingtonStreetStudios Thank you! 👍
I think I had an allergic reaction to the white earthenware. My eyes hurt for 2 days and my sinus went crazy. Does anyone have any insight as to what might have been in the clay that could cause that reaction?
Heather,
Sorry to hear about your reaction to your clay - the only thing that comes to mind is the possibility of mold in the clay. White earthenware is generally just intended to be a mixture of all inorganic materials: clays, plus possibly silica, and a flux such as talc.
Phil
Ed Sullivan..."We have a very good shew tonight, we'll be going to the Potters Roond Table.
It's a really big shew......love it!
I have hand built a piece and It’s a bit of a challenge to fire it. I can’t think of anyone better than Phil for advice on how to proceed. Is there an email address i can send a photo to with my question?
Yes, please send any photos and questions to washingtonstreetstudiosinc@gmail.com
Hey there. I'd love to do something for you. The white noise is super loud and I am very interested so im gonna power through that. But it would be super easy for me to copy this video and upload it or send it to you within the white noise. Not looking for money either. Just a dude :)
OK, what do you need me to do?
I left you a message on Facebook.
A micron is 1/1,000,000 of an inch not 1/1,000 of an inch.
Thanks Ronald, Phil figured that out after we posted the video but I was too lazy to fix it! Thanks for keeping us honest!
Micron is the old name for a micrometer, it would be 1/25400 of an inch
tooooooo many interruptions
Kathleen, sorry, this is how we keep the content free and keep the business operating. Perhaps you can find somewhere else to get this information that doesn't bother you so much.