Not sure if I would even try hot sand. You don't have to get the wood hot enough to ruin the finish. It doesn't take very much heat to expand the wood molecules in order to bend it. Think about it, if you leave your bow in direct sunlight or where it's very hot, the bow (over time) will warp on it's own.

I would think dipping the bow in hot sand would do more damage, I mean you're laying the finished wood in hot rough sand and the grains of sand can affect the smooth surface of the varnish. With the heat gun, you have a dry heat and the bow never comes in contact with anything. Heating the bow can also be done over the burner surface of an "ELECTRIC" not gas stove. I have found out that the heat gun works best, you can direct/concentrate the heat in a very small area if need be.

Heat and humidity, (as you probably know) is a very crucial part in the life of a violin/fiddle. Two weeks ago I had one of my bows rehaired, Monday morning I loosened the adjuster  to relax the hair, it still had tension on it. Thursday, I took it back to the Luthier who rehaird the bow. He asked me what the humidity was in my house. I wasn't there for more than 5 minutes and checked the bow hair again, it was fine, the hairs had relaxed and weren't tight at all. I was shocked that in just that short time, the affect the humidity in his shop had on the bow.

I think it was "Dee Major" who wanted a little more information on how to use the heat gun to straighten the bow.

Lay the heat gun on your table/workbench, support it so it doesn't vibrate all over the table, grasp the bow at each end, being carefull where you hold it by the head, the head is cross grained and it's possible to break it at that point. As you apply the heat, use gentle pressure in the opposite direction of the warp. Bend the stick beyond being straight, hold it in that position until the wood cools. You can also eliminate a twist in the wood, the same way, just twist the stick in the opposite direction. Make sure you apply the heat where the bend is, if the whole stick is warped, apply the heat the full length. With a small kink or bend, I lay the stick on my knee. The Luthier wanted $30.00 to $60.00 to straighten it and he does it the exact same way, with a heat gun. It took me about 20 minutes, for FREE.

I hope this information helps, it works for me.

LOL, I just read what you posted, Fiddlerman and that member was me. In the chat room I'm known as "Fiddleandbow". After I posted, I had to come back and edit this post.

Yeah FM, I thought about doing a video of that too, but my webcam cable is not long enough to reach, my 14 yr old "Sony" 8mm video cam has no adapter cable to connect to the computer so I can't do that.

It's a very simple process to straighten the bow, I did it on my 125 yr old Permambuco wood bow, then had it rehaired.

Fiddlerman said

I have the cheap bow that came with the violin that I sent to Huey. It is super warped so I will try it too. Maybe even make a video

I'd love to see that! 

I have tried to straighten  my bow as well, using heat lamp, I learned this technique from my father (he use direct fire since heat lamp, heat gun were not available to us, then). Basically, you apply heat on the side you want the wood to bend, e.g., if you bow is curved to the right, you apply heat to the left so the material would expand and allow rooms for bending. Do it bit by bit, so you would not burn the wood or damage the finish. However, i don't think this technique would work for carbon fiber bow.

Fish line for bow hair is just the synthetic bow hair.

You will need to tighten the bowhair to play, preferably apply some rosin before you play, you do not need to hold onto the bowhair to tighten it. you could learn how to hold a bow by watching the FM's video about it.