In general, preserving jars are suitable only for water bath canning and pressure canning at temperatures up to 130 degrees C. Most preserving jars are not designed to withstand higher heats of baking in the oven or microwave and can shatter under such use. It is also not recommended to sterilise jars in a hot oven for this reason. One brand is an exception and this is the Weck brand of jars which are certified as safe for baking. Note that these jars can crack if they experience heat shock, which is when the temperature difference between the jar and its contents exceeds approximately 20 degrees. If putting hot food into jars, ensure that the jar is prewarmed.