Questions about heat, steam and tempering

[Picklegiant]

Hello All

I am new to this forum, and bow building and after exploring this forum I have come up with some questions regarding modifying wood with heat and steam:

1. Is it OK to use heat tempering after the bow has been bent with steam? Will the added heat re loosen everything?
2. After steaming I know the wood can be dry as, steam has more volume that than water, so when the steam goes in the wood the existing moisture get pushed out, and the wood is left dry (I'm guessing because steam is less dense than water), therefore would it be safe to work with it right away, and how would one re moisturize their wood (I have heard about oil)? Does this drying out also happen with tempering?
3. And finally how can one quickly dry a stave, (I know it would be good to wait, but I only have a limited time to work the wood) Would putting it next to a heater or in a boiler room do it? And how do I maintain the right moisture in the stave, as I do not want to over dry me wood?

Sorry for all the questions at once

Ethan

[DC]

I've found that it is actually a good idea to heat temper after steaming. It seem to lock in the bend. Be sure to have a way to hold the bend while you temper or the heat will undo all your steaming efforts.
I try and leave wood for 24 hours after heat treating, steam or dry. If you are just doing a minor correction using dry heat you can work it as soon as it's cooled off.
Quick drying depends on the species. Some woods will split from stem to stern if you try quick drying.

[Del the cat]

1. Yes
2. I'm not convinced that steaming dries out wood.
3. Put it some where warm dry and airy, air movement/dry is as important as heat IMO. I've rapid seasoned on a radiator that jus tgets warm not how. It depends on the wood and your climate.
Del

[Picklegiant]

Thanks for the help, after steaming and tempering no oil is required to re hydrate it right?
In what ways can a quickly dry the wood, Ocean Spray and Maple staves and I live in a hot area

[Pat B]

I use oil when manipulating wood with dry heat. I think it holds the heat longer, distributes the heat better and helps to prevent scorching. I don't use oil when I'm tempering the belly. I want it to scorch the wood, hardening the belly making it more compression stronger. If you don't have much manipulating to do you can straighten and add reflex in one session using dry heat with no oil, ie. while tempering.
I rarely use steam although I may start using it for radical recurves to help prevent the outside of the bend from cracking while bending.
 When left along wood will eventually reach equilibrium, moisture wise, with the relative humidity of your area. You can reduce it even more by using a hot box or storing in your home with a/c. If you live in an arid area adding moisture is more important. Each wood has a moisture range that it preforms best at. Most bow woods like the M/C to be between 9% and 11% but hickory likes 5% to 6%.
 Most whitewoods can be quick dried in a month or two under the right conditions. Woods like osage and locust will take a lot longer. You can still build a bow with osage that is 2 months off the stump but you'll get lots better results from osage and locust that has been seasoned for at least a year and longer is preferable.
 When getting wood ready to dry be sure you seal the ends and the exposed back or it will check(crack) while drying.
 Water is not necessarily the culprit when it comes to moisture in wood. It is moist air that moves in and out of wood as the atmosphere changes. The word hygroscopic refers to this movement of moisture in and out of wood. Some woods , like hickory, are very hygroscopic meaning it takes on moisture easily and is slow to release it.

[Del the cat]

Thanks for the help, after steaming and tempering no oil is required to re hydrate it right?
In what ways can a quickly dry the wood, Ocean Spray and Maple staves and I live in a hot area

IMO, All oil will do is make the wood oily 
If you live in a dry climate you can always put the bow in the shower/bath room. In the UK rehydrating just isn't an issue.
Del

[DC]

I use Douglas maple and I've never had a checking problem. If I had lots I would try to quick dry it. I live in a damp area though.

In my opinion you can't quick dry Ocean Spray. I've found that if you split or cut the stave right down the middle so that the pith is exposed they dry way better. Unfortunately OS is usually too small to get a handle out of the split piece. I cut them like the picture and run a saw kerf through the handle section. Shellac the back, ends and handle area. Again I live in a damp area and OS is tough to dry here so if you're in an even dryer area you will have to take more precautions. I'm trying some billets at the moment. I put them in plastic bags like the kind root vegies come in, you know, with the 1/4" holes punched in them. So far so good but I will leave them for a year. I know it's tough to leave them that long when you are starting. You can make a bow with "not quite dry OS" but it will take a lot of set. It's kind of neat though, you start out with a dampish 40# bow and as it dries over a years time the weight will go up to maybe 50# . It will still have a lot of set though.

[Pat B]

Del, I find it easy to remove the oil with a wipe down of alcohol or acetone. Also it is eliminated with wood removal in the final tillering. That oil doesn't penetrate very deep in my experience.

[DC]

This is what happens to OS that dries too fast. I think I can split it open and make kids bows.

[jeffp51]

There was a thread a few months back using mylar/plastic tubes for steaming but I can't find it now. Anyone have the link?

[Del the cat]

Del, I find it easy to remove the oil with a wipe down of alcohol or acetone. Also it is eliminated with wood removal in the final tillering. That oil doesn't penetrate very deep in my experience.

Yup. I use it when heat tempering, but I don't think it rehydrates the wood... which is what I thought was being asked .
Del

[JoJoDapyro]

For steaming I use a 2 gallon stainless pot with a lid. A PVC elbow threaded into the lid, and a 2 inch PVC pipe.

[DC]

There was a thread a few months back using mylar/plastic tubes for steaming but I can't find it now. Anyone have the link?

http://www.primitivearcher.com/smf/index.php?topic=52364.0

[DC]

For steaming I use a 2 gallon stainless pot with a lid. A PVC elbow threaded into the lid, and a 2 inch PVC pipe.

Good thinking. I've always just thought that the whole thing had to be sealed but it doesn't does it? At the very most you could put a rock on the pot. I over think when it doesn't matter and under think when it does

[Picklegiant]

What does the quick drying process consist of