I guess that might be a safety feature. Anyway, I put the battery back in but now the alarm emits small beeps like every two minutes or so. Why?
IF the polymer has been baked rigid to make a reusable mold, if the release works you may still have trouble getting the casting out unless it is shaped exactly right. A soft latex or silicone rubber mold (latex backed by plaster) may work better for a limited run - each of these from a modeling clay original - how will you make the polymer clay (not really modelling) mold - from a model or by hand shaping it.
Yes both fitting and pipe should be cleaned and use a silver bearing solder for potable water and the proper flux for that type. not all are the same. a wet rag for wiping after is good practise as you can also use it to put out fires. The wiping cleans off any excess flux that would turn the fitting green after a while. Make sure you have no moisture present as this will prevent solder melting.
