Ultimately, we can't tell you exactly how long you can leave butter out. We have no problem with leaving butter out to soften as long as it is well-covered. It usually doesn't take us more than a couple days to go through a stick anyway! We've never had rancid butter in that time.
For complete instructions, see my weekly column. Note: The vinyl melts in just a few minutes and is warm to the touch when you pull it from the 200-degree oven (don't use a hotter oven or the vinyl will start releasing toxins). You can form it by hand immediately, but use leather gloves if you're nervous. All beginners in Record Upcycling should try a bowl.
Confidence votes 115. Pure paraffin melts at about 125 F, but candle wax is not pure paraffin so it will be a little different. If you are trying to pour the wax into a mold, metal molds require the wax to be between 180 and 200 degrees F. For paper cartons, glass, rubber, etc., the pouring temperature is 130 to 150 degrees F.