Many ceramic containers could be safely placed over a flame if they were separated by a “flame spreader.” You might remember the wire screen under the beaker, suspended by a tripod above the bunsen burner flame in your chemistry lab class.

When heated over a direct flame with NO flame spreader, the bottom-outside ceramic surface at the tip of the flame heats very rapidly and expands quickly, whereas the bottom-inside and bottom-mid portions of the container wall heat and expand more slowly. It is the differential expansion of the outside and inside surfaces that cause the container to crack.

A wire mesh flame spreader (with or without an embedded asbestos mat) spreads the flame heat over a wider area, at least 10 times compared to directly heating a tiny hot spot above the flame tip. That means the heat at any point above the flame spreader is no more than 1/10 the heat at the tip of the naked flame. Thus, no point overheats suddenly and the entire area and thickness of the bottom wall gradually heat up without massive differential expansion and cracking.

Notes: (1) Never heat empty glass or ceramic containers without some liquid inside because if might crack even with a flame spreader, and would most likely crack when you add a liquid to the heated container. (2) If the bottom wall of the container is very thick, even a flame spreader may not give adequate protection if the flame is big and hot. (3) Glass and ceramics may crack if heated directly on an electric stove; again, a flame spreader would help. (4) Your glass or ceramic containers have a better chance of survival with a flame spreader if you apply heat gently–start with a small-medium flame or start with a cold electric element! This is the principle of thick-walled ceramic slow cookers–increasing from low to medium heat.

I know where union church is (is it the one at the corner of rada and legazpi streets?)…i will try and come around one sunday…

thanks…

I thought the picture was candied kundol….

What is the nearest landmark to Legazpi Market?