Here's a small little video I've been working on. As the title says, this is a guide on how to effectively superheat Gold Ore for fast, cheap, easy Magic and Smithing experience.
Superheat Item requires level 43 Magic to cast and gives 53 experience per cast. Level 40 Smithing is required to smelt Gold Ore. Normally, smelting Gold gives 22.5 experience, but when using Goldsmithing Gauntlets (a reward from the Family Crest quest), that Smithing experience is boosted to 56.2.
Superheat Item can be cast once per two game ticks (1.2 seconds) compared to High-Level Alchemy, which can only be cast once per five game ticks (3.0 seconds). Unfortunately, Superheat Item requires you to bank, but still, it is much faster than Alchemy. Using Alchemy with perfect timing, you could only get 1200 casts per hour, which is 78,000 experience. However, even when you're not at full concentration, you can cast 2200 Superheats per hour, which is not only 117k Magic xp per hour, but also 124k Smithing xp. You're basically getting triple the xp from Superheating compared to Alching.
Tip: To avoid tiring your fingers, switch which fingers you use to click - this is especially easy if you have mousekeys on, which allows you to use the "5" button on the number pad to click. You can also use the "+" button to instantly superheat (as it double clicks), however last time I checked that was against the rules (one button that performs two clicks is not legal).
The repeating clip at the beginning of a player casting Superheat Item is from the RuneScape Wiki. I am allowed to use it by the CC license. Also, to check gp/xp charts of Superheat Item, the following Wiki page has them:
~Children (Dream Version) - Robert Miles
Q: Are there other effective methods of Superheating (different ores)?
A: Yes, however none give as much experience as Gold (Iron yields the same Magic xp, yet far inferior Smithing xp). However, there are also some ores that may give far less xp, but net a profit, which is always something worth checking into. If you're interested in making a profit this way (at the sacrifice of xp), then check the above (also below) Wikia page to get the most current information.
Q: What about Smelting Urns?
A: Good question - Smelting Urns do work while Superheating, but NOT while smelting Silver or Gold Bars. If you're Superheating anything but Gold or Silver, feel free.