You get what you pay for as far as candles are concerned. The quality of wax, jar, and wick varies. Longevity of use is related to quality (price) and proper usage. Very inexpensive candles are scented by putting a perfume on top after the candle is made. High quality candles are scented throughout the wax with wicks that are tested to be the proper size for the container. They are not made in China. The amount of scent a candle can produce is a product of the surface area of the melted wax, and the amount of scent within the wax. In regard to keeping old wax, I say absolutely! In addition to using it to make your own candles, sachets, and melts, you can add small chunks to other candles. I prefer to do this after it starts to cool off and shrink. Just push new chunks of wax in the soft candle to offset the shrinkage and it will all melt together next time you light it.

I just did this for the first time and candles are setting as I'm typing this. I used several old and dusty/dirty looking candles. I didn't worry about cleaning them or anything. The candles I used were all similar though. I'm not sure how different types of candles would work together since this was my first try. When my wax was all melted I did have some debris at the bottom of the pot. I was careful pouring once I got to the last of the wax so that none of the debris ended up in my mold/jar. So far they look fine as they are setting up. Hope this helps.

Here's a Martha how to. The Vybar is key, and the beeswax wouldn't hurt either. Especially if they were used as holders for a burning candle. Here is a link that might be useful: Wax Bowl..Martha Stewart

I'd be really worried heating it would ruin the red portion of the holder??? Suggestion? Does it move at all if you gently put a tip of a knife inbetween the candle and holder? Believe it or not, most all pop out of my holders that way. I guess, If I heated it, I'd try to hold the bowl part over an open flame (obviously it can handle that as it's meant to hold one) a bit, until it moved? Maybe.