Care instructions

Dear Customer, 

Thank you so much for purchasing our product. In order for you to enjoy our glass for a long period of time, we’ve assembled some safety points below. Hope you will find the information useful. 



Koizumi Glass Works Co.,Ltd.


Article: Heat-resistant glass utensil
Classification: Use for hot water. 
Heat resistant temperature difference of up to 120 ℃
(The temperature range that can withstand rapid cooling and heating)
Material: Borosilicate glass 

*Do not use the product for any other purpose than as classified. 

Wash and dry well before using it for the first time.


How to clean

Use a sponge or soft brush when cleaning. Do not use metal or steel brush, cleanser, or abrasive cleanser sponge as it will damage the glassware.


About the glass

Each glass is different in size and shape. It is due to the fact that our glasses are hand blown by our craftsmen. In addition, you may also notice some bubbles or lines on the glass surface. These are not faulty but features which we hope you will find as a beautiful characteristic of the handmade item. 

Precaution for use

Do not use the product if you find a crack, chip or deep scratch on the glassware. Continued use of a damaged product can be extremely dangerous.  

Do not put the product in oven or microwave or use on stove. 

The glass can be very hot so please use oven gloves/mitts to hold it when it is hot. Do not put a damp cloth on the glass or place it on a wet surface when it is hot.

Handling the leather holder 

Remove the leather holder before cleaning the glass

Leaving the leather wet will cause it to lose its shape and get mouldy. Make sure to dry it with a cloth. 

When washing the leather holder, remove the strap before lightly handwash it (but do not rub or hard wash) with cold or lukewarm water. Wipe off the moisture thoroughly and dry in a well-ventilated room.

When removing the leather holder, hold the glass firmly on a very stable surface.