Boiling tips to recurve them, how long?

[Lorenzo]

Hi!

I want to recurve a rattan bow by boiling the tips.

I leave it boiling for about an hour and then bend it. How long should I let it set?

Is there any way to speed up the drying process? (Ex: heat gun?)

Thank you very much

[stuckinthemud]

There is no rule for how long to leave it. Leave until its completely cool, that is the middle must be cool, not just the outside. Most of us would leave it overnight just to be safe by which time it would also be dry.  Drying time depends on air movement, temperature and relative humidity as well as how absorbent the timber is.  It is common practice to lock in the new shape with a heat gun but if you rush too much you risk splitting the wood

[gutpile]

I have two videos on recurving bow help . one is set up the other is bending the wood.. as for how long to leave  I leave on form overnight.. I do not dry heat after I boil it as this could cause it to check ..as for boo it is very hygroscopic so I certainly wouldn't put dry heat on it for at least a week.. gut

[bownarra]

If you have heated it up enough to bend successfully you shouldn't go near it with a heatgun after boiling.
Boil 30 minutes for every 1/2" of thickness.
I wonder where this dry heat thing came from. If the wood is hot enough to bend it has reached plastification temp. Blasting it with more heat afterwards is going to achieve what? It is already bent! If it springs back a large amount you just didn't get the heat soaked in properly (and you are lucky the tip didn't snap off!).
Soak in water for a few days first. Boil under water. Bend on form quickly. Leave overnight. Do the other one .

[PatM]

Because it works  and you can lighten the tips more. That's what started it.

[Marc St Louis]

Heat-treating recurves after steam bending will set the recurves in place but it has to be done while the recurve is still in the bending jig otherwise they tend to straighten out a bit.  Don't know if boiling changes that as I always steam bend

[bownarra]

I should have phrased that differently. I know why people do it but I have never found it to be necessary. Heat treating the wood of the recurve after it has been bent/cooled. That I can understand. Springback happens because the centre isn't hot enough in my experience (of course some springback will always occur I'm talking about an excessive amount). You either got it hot enough all the way through or you didn't in my expeience. Boiling in water helps to avoid any spots with different temperatures.
I'd be interested to know if any other trades/crafts who heat bend wood think it is necessary to do all the bending then heat again....
Bear in mind that too much heat will tip the odds the other way and your recurve would actually have to be larger to have the required stiffness.
I also found it useful to make some test recurves and see just how small tips can be made. Most wooden bow recurves are too big in the first place. I've found that 10mm width by 14mm deep is enough for upto 80#. The problem isn't really the size/weight of them it is keeping the thing lined up when you reduce the tips as small as they can be. So Pat have you got any pictures of your heat treated recurves to see how small you've made them after heat treating??? I'd be interested to compare.

[PatM]

The way I see it is that heat treating a reflex in a limb will hold while steaming or boiling one in will not.

[RyanY]

In the past I had not had a lot of success with boiling recurves or steaming them over a pot of water even for well past the recommended times. I would often get spring back after the wood had cooled down. For some reason hitting it with some dry heat after seemed to prevent that. I don’t think it’s necessary to do it right after boiling/steaming. Just while it’s in the form. My new recurve setup uses a garment steamer for the heat source and traps the steam in a plastic grocery bag. It has worked much better than the methods I had tried before. I think the current method is hotter. People have had success with a lot of different methods. Have to find something that works for you.

As mentioned, once the area has cooled down it should be set. Doesn’t take very long to cool down so no need to rush it.

[simk]

same here - no more creep back since I do "set" steamed/boiled stuff with dry heat. I do it every time I steam/boil something.
my personal explanation (from different reads about industrial heat treating of wood/production of so called "thermo wood"): the plastification process and further structural changes in wood needs a temp. of 160+ degree celsius. You simply dont reach this with just boiling or steaming the wood. But I'm not a scientist, finally just do what works by try and error