Primitive Archer

Main Discussion Area => Bows => Topic started by: Rākau on June 23, 2019, 02:13:55 pm

Title: humidity and EMC: how wet is too wet?
Post by: Rākau on June 23, 2019, 02:13:55 pm: Hi guys, I have a a few querys, to which I think I know the answer but would like to hear your opinions. kind of a follow on from an earlier post, "how dry is too dry" by dieselcheese.

where I live has a year round RH of 75 +, at the moment RH is 80-95 with temps from 5-20 °C. an EMC chart places wood kept in these conditions firmly in the more than 14% MC range:
1) how would you alter design parameters to suit these conditions?
2) what would you expect from bows that live in these conditions?
3) what would you expect from a bow made in these conditions and then moved to conditions of say 60% RH?
4) the wood I predominantly use seems to take a fair bit of set, and benefits from a late tiller heat treat and reflex is this easily explained by the RH levels?

thats all for now, feel free to answer 1, none or all of the above haha.
Title: Re: humidity and EMC: how wet is too wet?
Post by: DC on June 23, 2019, 02:47:49 pm: I have similar, but not quite as wet, conditions. I built a warm box to keep my staves in for a month or so before I make a bow. If you make bows with 14% MC you will get set. Is your house air conditioned?
Title: Re: humidity and EMC: how wet is too wet?
Post by: Rākau on June 23, 2019, 03:26:17 pm: nope not air cindconditioned, but there is a fire place up stairs and the RH up there is 50-60%. haha I do make bows that must be about 14% MC and they do take a bit of set. previous to when I started doing combined heat treat/reflexing they normally came in between 1.25 and 1.75" of string follow (probably 2-3" of set from where they start)
I was hoping to avoid making a hot box, but it may be inevitable.
Title: Re: humidity and EMC: how wet is too wet?
Post by: DC on June 23, 2019, 04:33:33 pm: It doesn't have to be that big. It just needs to hold enough staves to keep ahead of the drying. If you put a thermostat in it they are minimal work/care. Keep a hygrometer in there. It has to be vented to let the moist air out. Most people use light bulbs for heat but they can break. If you can find an old waterbed heater they work great and come with a thermostat.
Title: Re: humidity and EMC: how wet is too wet?
Post by: Rākau on June 23, 2019, 07:59:34 pm: the thing with that is keeping them at the correct MC after they are made, do you just always keep them in a box?

if they are overbuilt could that minimise set with High MC?

how about an electric blanket as a heat source, they normally have a basic thermostat built in
Title: Re: humidity and EMC: how wet is too wet?
Post by: DC on June 23, 2019, 09:31:56 pm: I don't know about the electric blanket. You would have to wrap them in it and then the moisture may be trapped in there. If you can find a place that hovers around 50% RH in your house. I moved a hygrometer around until I found a spot in the hall that averages about 55%. It seems OK.
Title: Re: humidity and EMC: how wet is too wet?
Post by: Rākau on June 23, 2019, 11:09:02 pm: nice, I'll go humidity hunting round the house over the next few days and see what I can find. thanks for your input DC.
Title: Re: humidity and EMC: how wet is too wet?
Post by: NicAzana on June 24, 2019, 01:28:20 am: I live in similar conditions (maybe slightly better) here in Denmark. I've just ordered a hygrostat (like a thermostat, only using RH instead of temperature) and a dehumidifyer, and am going to try to set up a 'controlled' environment up in a tiny room we have upstairs. Going to try to keep the air in there at 50-55% RH, and store my bows and staves up there. Neither gizmo was very expensive.

Anyone else try something like that?
Title: Re: humidity and EMC: how wet is too wet?
Post by: DC on June 24, 2019, 07:12:29 am: My warm box has a dehumidifier hooked in to it. I can set the dehumidifier at 50% and it does the rest. I think the box(It's about coffin size) is a little too small for the cycle pattern of the dehumidifier. It seems to cycle on and off to often but it does sort itself out after awhile. Your small room will probably work better.
Title: Re: humidity and EMC: how wet is too wet?
Post by: Pat B on June 24, 2019, 07:29:02 am: There are electric rods that folks used in their closets to minimize moisture. A simple box of foam board and one of these "dehumidifiers" should work for you.
Title: Re: humidity and EMC: how wet is too wet?
Post by: DC on June 24, 2019, 08:25:37 am: I like those. Much better than light bulbs.
Title: Re: humidity and EMC: how wet is too wet?
Post by: Rākau on June 24, 2019, 01:20:21 pm: thanks guys, I will work on sussing out one of the above solutions. apreciate the input!
Title: Re: humidity and EMC: how wet is too wet?
Post by: Mesophilic on June 25, 2019, 02:18:07 pm: Hope you get your humidity situation figured out.

FWIW, as of 13:45 today we're at 86°F with relative humidity of 6%...yeah you're reading that correctly...single digit six percent humidity...soooo looking at the chart, is says I'm in the "you're screwed" section.

I have to back my backing >:(. Working with sinew and it's so dry it's like working with glued down straw. The hide glue seemmsvery brittle anddsinew fibers lift up like crazy. So far a layer of silk over the sinew seems to do the job but we'll see.