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Balsa warps

Old 06-11-2015, 08:29 PM
  #1  
hkeelljr
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Default Balsa warps

Purchased a couple of sheets of 1/16 balsa yesterday so I can rebuild the fuse for the Valylrie and left it in my shop last night. Went into my shop this morning and it had warped, which has happened before. This is good Sig balsa and it ticks me off. I'm thinking that since the lhs is air conditioned and my shop isn't could this be the problem or is it something else? Oh well guess I'll wait until Monday when my weekend stint at work is over, maybe by then the warp will be gone.
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Old 06-11-2015, 09:36 PM
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solentlife
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Humidity causes the warp ............. you can try damping down the wood and then 'iron' it flat .... but often once its warped - its hard to get back again.

Nigel
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Old 06-11-2015, 10:40 PM
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fhhuber
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A bit of ammonia in the water, get the balsa damp. Weight it flat. Works every time.
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Old 06-12-2015, 04:52 AM
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I agree here ,use wetter water . That's what fireman call it. It allows things to become weter faster and deeper. Almost any detergent will suffice. Once wetted, you have to try to control the shape while drying . The wetting kinda super relaxes the fibers involved.
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Old 06-12-2015, 06:23 AM
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these bends are done with ammonia soaked spruce.

Ammonia actually softens the substance in wood that bonds the fibers together... allowing them to slide. Then as it evaporates it hardens again.

Its not just "wetter water"

Its a solvent for wood.
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Old 06-12-2015, 02:19 PM
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FHhuber, What you show is very interesting, I never tried that. The thing for me is the spruce.That's cool. I'm thinking along bow making lines.Do you think ,once dry, that there would be any limits put on the fibers .Like for flexing?
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Old 06-12-2015, 03:49 PM
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Thank you for the explaintion. That's really good to know. I am still learning something new everyday,at 72. Who said you can't teach an old dog new tricks. Thanks again.
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Old 06-12-2015, 05:50 PM
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Originally Posted by fhhuber View Post


these bends are done with ammonia soaked spruce.

Ammonia actually softens the substance in wood that bonds the fibers together... allowing them to slide. Then as it evaporates it hardens again.

Its not just "wetter water"

Its a solvent for wood.
If I remember my Biology and Chemistry - its the interaction of the Ammonia and Cellulose that allows it .. same as steaming where we bend strakes for boats etc. - the heat acts on the cellulose of the wood plus the wood softening.

Nigel
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Old 06-12-2015, 06:17 PM
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Generally for bow making they use steam bending, but ammonia is better when doing lamination in combination with bending for structures like the Sopwith tail-planes and wingtips.

Full scale Sopwith they were steam bent and not laminated.
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Old 06-12-2015, 07:26 PM
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But of course Bow-making has a specific construction of different woods on outside and inside of the 'draw' to give it strength but also draw tension.

Nigel
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Old 06-12-2015, 09:21 PM
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The ammonia actually softens the cellular structure so that when it re-hardens, it stays that way as the cells physical structure is actually permanently changed and less susceptible to warping should it get damp again. Pure ammonia is actually better than a mix with water, especially if the wood is quite thick. Put it in long tube full of ammonia and leave it over night and it will be quite pliable and easily formed.
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Old 06-12-2015, 09:51 PM
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Pure ammonia is something most people shouldn't be playing with... Very easy to kill yourself with it.
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Old 06-12-2015, 11:02 PM
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Originally Posted by fhhuber View Post
Pure ammonia is something most people shouldn't be playing with... Very easy to kill yourself with it.
My office is in the terminal Ventamonjaks ..... Ammonia and Acrylanitrile export terminal. You think Ammonia is bad .. check out ACN ..... nicknamed Peardrops due to the smell.

Nigel
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Old 06-13-2015, 12:39 AM
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There's worse stuff, true.

Like HF.
There's some really nasty stuff.
Inhale the fumes, it mixes with the moisture in the lungs, forms Hydrofluoric acid and dissolves you from the inside out.

But pure ammonia can produce fumes fast enough to kill you before you know what's happening. Or added to common tap water it will force the chlorine out as a gas and that will ruin your day.
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