I've had good results with a wet towel and a hot steam iron on the cupped side of warped boards but never on a long stemmed goblet. it might be worth a try.

Thanks guys. 

Tony Allwright wrote on Dec 13^th, 2017 at 4:16am:


When trying to bend wood, your are trying to have wood that can absorb compression and tension forces without failure.
The steam carries the heat along with moisture (obviously), this slightly raises the MC of the wood and also eliminates the risk of scorching. The steam temperature is roughly similar to the temperature where the lignin (organic polymer that stiffens wood) starts to soften.
When the lignin softens, the wood looses some rigidity, combine this with a higher moisture content (think green wood) and the wood is much more acceptable to bending (compression on one side, tension on the other)
Using dry heat can also cause brashness. Heating to too high a temperature for too long can weaken the wood. This is almost impossible to regulate with a heat gun.

Wood will always bend easier and further the first time.
Re-bending is more difficult but with correcting a warp or slight curvature in something as small as a goblet stem it should be able to be done.
For small items (like a goblet stem) I have used a tool that was intended to train bonsai branches. It can placed on the affected area. Apply steam and increase clamping pressure and allow to set/cool.
Example
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You touched on the main point Ron, which is IMO control.
Thermal blankets and even light bulbs have a known amount of heat output, constant and uniform (in most cases).
Also when using irons and heated forms, often the wood is saturated or soaked in water beforehand. Pre-soaking softens the wood fibers, (like soaking reed for baskets) the dry heat softens the lignin and allows for easier bending.
Dry bending can be scary and is dependent to a great degree on the wood species. being used.
This is why, unless you are skilled in the science/art of bending, I don't suggest using a heat gun.

For those interested, here is an article on bending wood. Although it's directed at luthiers, the principals are the same. Multimedia File Viewing and Clickable Links are available for Registered Members only!!  You need to or

When I was building canoes, we used a steam generator. Tea kettle and plastic pipe to hold the ribs.

Glenn J.

Glen
Did you manage to straighten the stem on the goblet and if so what technique did you use.
Tony