Our general guidance for Heat-On is that blocks (including inserts) and covers can be used at up to 200°C without damage to the block or cover, and that up to 260°C could be achieved but there is a risk of some slight damage – polymer-coated Heat-On blocks may have some coating degradation, anodised blocks may become discoloured, and PTFE covers may experience some distortion.
For the polymer-coated blocks, 200˚C is fine but above this the coating may be damaged by prolonged high temperatures. Very high temperatures are more likely to lead to more damage (peeling etc.).
Anodised blocks do not have this risk of coating damage. At very high temperatures, the block may become discoloured, but this is an appearance issue only.
We can’t give data on exactly when (times and temperatures) damage starts / is significant; in addition to temperature, the risk/extent of any damage will be affected by factors such as how old the blocks etc. are, how much they’ve been used previously, and what chemical exposure they’ve had.
In terms of the maximum temperature a Heat-On block is physically able to reach, this will depend on the heat source, heat transfer and heat loss etc. – various factors including the particular magnetic stirring hotplate used, the load to be heated, and the ambient temperature etc. Some customers report adding insulation to the flask, and reaching temperatures as high as 280˚C, although we cannot make any guarantees.
If you would like to work at high temperatures, we would advise selecting the anodised version of Heat-On, as then there is only the risk of discolouration, rather than coating coming off.