Including UK VAT*

What You Will Learn

Creating crackle textures with kiln-formed glass powders was pioneered by Bob Leatherbarrow who has continued to explore and develop its design potential over the past 30 years. In this four-session masterclass, Bob will share his knowledge of crackle textures starting from the foundations and advancing to complex designs and compositions.
These foundations include learning proper techniques and problem-solving so you can control subtle aspects of the crackle such as the size of the “islands” in the texture. Layering and blending of powders result in unique colour palettes and Bob will explain the placement of accent colours and the importance of sequencing colour layers. You will also learn how to develop your own unique and reproducible colour palette and work with reactive colours.

With these foundations in place, you will discover ways to include subtle veining and “replacement” textures, isolate the texture in specific parts of the design, and work with different combinations of textured powder and sheet glass. These concepts will take your crackle texture pieces to a whole new artistic level.

For those who have taken Bob's 'Textured Powders' in the past, 50% of this course will recap the famous crackle technique you've seen before. The other 50% is brand-new material covering processes and design elements in powdered works.

 See more of Bob's work here:

Creating with Crackle Bob Leatherbarrow Materials List 2023.pdf

Duration and Place

4 weeks, one session per week - a total of 6 hours

Online Course

Please note that classes may be slightly longer or shorter depending on student questions.

Session times

  • Wednesday 10th January- 5.30 pm-7 pm UK time (1.5 hours)
  • Wednesday 17th January - 5.30 pm-7 pm UK time (1.5 hours)
  • Wednesday 24th January - 5.30 pm-7 pm UK time (1.5 hours)
  • Wednesday 31st January - 5.30 pm-7 pm UK time (1.5 hours) 

Workshop Outcomes

  • 3 projects 15cm in diameter to learn the basics of the crackle technique
  • One of the above 3 projects to be used in an “encased” crackle project
  • 1 square colour-filled  veins project which is a variation of the basic crackle technique
  • 1 round project where the texture is limited to the rim of the circle
  • Test tiles and reaction strips that demonstrate colour blends
  • 1 round project that incorporates blending colours, veining and replacement texture
  • Projects from this course are sized to fit in slumping moulds resulting in finished pieces
  • Practical information on coldworking edges, finishing surfaces with and without a sandblaster, slumping, bubble control and developing firing schedules

How it Works: 

  • The course is made up of four live and interactive online sessions using the Zoom platform. These can be found in the navigation panel.
  • Bob will give a step-by-step tutorial with demonstrations, and you will have ample opportunity to ask him questions during the live class
  • Each week they will demonstrate a technique for you to try between sessions
  • A member of the Glass School team will also be in the Zoom class to assist you and Bob
  • Mix with Bob and other students on our dedicated community page, open for the duration of the course. Then join our exclusive Glass School UK Online Glass Community Facebook group to continue to mix with those who have attended any of our online masterclasses
  • A materials list is provided in the course navigation panel, so you can purchase what you need to create your pieces during the course. You don’t need absolutely everything on this list to be successful, Bob will discuss different ways to reach our technical goals

We believe that this is the best way to get the very most from the course, but if this doesn’t suit you that’s fine: - If you can’t get to your studio, you can still learn the techniques and benefit from Bob's extensive knowledge without making the pieces during the course itself.

This is a live online masterclass, but in case a student experiences issues with internet connection during the live class, a recording of each live session will be available to view until two weeks after the final session. This cannot be downloaded or shared and is only available for this limited time. By participating you agree to be recorded for this purpose.

These recordings will be available in the course navigation panel. 

What to Prepare

  • You will need a computer, tablet, or phone with a camera and microphone in order to join the online classroom. If you are unfamiliar with using Zoom then please take some time to look at our guide, available in the navigation panel. 
  • You should have a reliable internet connection, fast enough to make video calls or stream videos
  • Please read the Student Participation Agreement
  • Ensure that you have checked the materials list and purchased any materials you may require 
  • A pen and paper to take any notes. 
  • We restrict the class size to 25 people
  • We teach using Bullseye Glass (CoE90)


We are committed to maintaining a respectful community where all our students can learn and develop their full potential, within a safe environment.

If you have a disability or any specific requirements, please do not hesitate to contact us prior to your lesson so we can accommodate you.

*Price excluding VAT is £150. The correct tax will be calculated at checkout based on your location.

Cancellations up to 2 weeks before the course receive a 90% refund, after that date, a 50% refund will be given up to one week prior to the course, and no refund is given for cancellations after this time. In order to keep class costs low for all, we make no exceptions to this policy. In order to cancel your place on the course please contact [email protected] 

What Our Students Say

Nancy, B.

This was such an amazing class overflowing with information, great slides of techniques, answers to every question, inspirations, challenges... and then the videos.. WOWZA!

Dot W.

A carefully planned course where every step was so clearly explained that there were few questions to ask. There were plenty of downloads to support the projects. On top of that, Bob has such an engaging manner that it was a pleasure to listen to him and watch how he works.

Janet, R.

Thoroughly enjoyed this course, jam-packed with with information and ideas to go away and create your own masterpiece.

Course Curriculum

    1. Welcome

    2. Course Overview

    3. Student Participation Agreement

    4. Join the Community!

    5. How to Navigate the Community Page

    6. Materials List

    7. How to Download your Materials List!

    8. A Guide to Zoom and the Live Session

    9. All Set for the First Session!

    1. Welcome to Week One

    2. Introduction to Kilnformed Powders eBook

    3. Zoom Link - Week One - Bob Leatherbarrow - Wednesday 10th January 2024

    4. Week One - Recording

    5. Exercise 1 : Water Powder Ratio

    6. Exercise 2: Controlling the Size of Your Islands

    7. Exercise 3- The Importance of Layering of Coloured Powders

    8. Exercise 4: Strip Cutting

    9. Creating with Crackle Week 1 Presentation

    1. Welcome to Week Two

    2. Zoom Link - Week Two - Bob Leatherbarrow - Wednesday 17th January 2024

    3. Week Two - Recording

    4. Encased Crackle

    5. Creating with Crackle Week Two Presentation

    1. Welcome to Week Three

    2. Zoom Link - Week Three - Bob Leatherbarrow - 24th January 2024

    3. Week Three - Recording

    4. Design Project

    5. Creating with Crackle Week 3

    1. Welcome to Week Four

    2. Zoom Link - Week Four - Bob Leatherbarrow - Wednesday 31st January 2024

    3. Week Four - Recording

    4. Week Four: Blending

    1. Submit Your Finished Works

Bob Leatherbarrow

Bob Leatherbarrow established Leatherbarrow Glass Studio in Calgary in 1988 and has created original kilnformed glass ever since. Known for his innovative styles, techniques, and designs, Bob has taken an experimental approach to developing unique textures and colour palettes using glass powders. His kilnformed glass bowls and sculptures explore the subtle hues and delicate beauty of naturally occurring textures and encourage the viewer to ponder their origin. In 2008 Bob moved his studio to Salt Spring Island, British Columbia where he now makes glass art and writes e-books on his signature techniques. Bob has been a popular guest instructor on both the national and international kilnformed glass scenes.

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Learn this unique technique and take your glass work to the next level