# Removing Runny Glaze From Pots and Shelves

Unit: The Final Bake: Glaze Firing
Topic: Kiln Shelf Grinding
URL: https://claybook.studio/learn/removing-runny-glaze-from-pots-and-shelves/

# When Glaze Runs: Damage Control

Even experienced potters occasionally have a glaze run: a pot where the glaze flowed down and stuck to the kiln shelf, or pooled around the base of another pot. Knowing how to deal with the aftermath saves both the pot and the shelf.

## Glaze Stuck to the Shelf

If a pot has fused to the shelf with hardened glaze:

*   **Do not force it.** Trying to lever a pot off a shelf by hand will crack the shelf or the pot.
*   Use a **chisel and hammer** to carefully chip the glaze crust around the base of the pot. Work in small taps around the perimeter, not one heavy blow.
*   Once the pot is free, grind the remaining glaze off the shelf with a rubbing brick. The kiln wash under the run should have protected the shelf itself.

## Grinding the Foot Ring

After a run, the bottom of the pot will have sharp, hardened glaze residue. Use a **diamond grinding pad** or a **bench grinder** to smooth the foot ring so it does not scratch surfaces. Always grind in a wet environment or wear a dust mask; glaze dust contains silica and flux materials that are harmful to inhale.

## Preventing Runs in the First Place

*   Wipe the bottom 1 cm of every pot clean of glaze before loading.
*   Keep glaze thickness consistent; thick glaze flows more.
*   Test new glazes on small test tiles before using them on finished pieces.
*   Never trust a new glaze on a treasured piece the first time you fire it.

## Run-Risk Triage
When loading:
* Place known runners on higher shelves over catch tiles
* Give risky pieces extra foot clearance
* Keep a mental note of which combos need thicker wash under them

This way, occasional experiments do not take whole shelves with them.

The maintenance work is unglamorous, but it keeps your studio running and your work coming out cleanly. Every skilled potter knows their grinding brick as well as they know their favourite tool.

## Keep Exploring

Preventing glaze runs is closely tied to understanding [glaze defects](https://en.wikipedia.org/wiki/Glaze_defects) and how different glaze chemistries behave at temperature. The discipline of testing new glazes on small tiles before committing them to finished work is a hallmark of [studio pottery](https://en.wikipedia.org/wiki/Studio_pottery) practice worldwide.

## Common Mistakes and Quick Fixes

*   **Trying to pry fused pots off by force**: Chip carefully in stages instead.
*   **Not smoothing run scars on feet**: Grind feet clean so finished pieces are usable.
*   **No risk strategy for known runners**: Place risky ware over catch tiles and safer zones.
*   **Skipping post-mortem after a run**: Record glaze combo and thickness to prevent repeats.

## Practice Exercise

Build a “run-risk” list of your top five glazes, with notes on overlap behavior and safe placement zones in your kiln. Update after each firing. This converts accidental runs into controlled experimentation.

## Check your understanding

### Question 1: What is the correct way to remove a pot that has fused to a kiln shelf?

- [ ] A. Lever the pot off the shelf by hand using a flat tool
- [x] B. Chip carefully around the base with a chisel and hammer in small taps
- [ ] C. Refire the kiln to re-melt the glaze and free the pot
- [ ] D. Soak the shelf in water overnight to dissolve the bond

Tip: Use a chisel and hammer to chip around the base carefully in small taps. Forcing the pot off by hand risks cracking the shelf or breaking the pot.

### Question 2: What is the best way to avoid glaze runs in the first place?

- [ ] A. Fire at a lower temperature so glaze does not flow
- [x] B. Wipe the bottom centimetre of every pot clean of glaze before loading
- [ ] C. Use only matte glazes, which do not run
- [ ] D. Place a catch dish under every pot in the kiln

Tip: Wiping the bottom centimetre of every pot clean before loading is the single most effective way to prevent glaze from running and fusing to the shelf.