I've heard that heat is the key, regardless of the method, Ie an iron on high heat will work as well as a steam bending rig.

Nick

Clothes steamers work well.

I've heard about using an ammonia solution to bend wood for years, but have never found the need to try it out. I've also heard of soaking the wood in fabric softener---.

Craig may probably be right, in that household cleaners don't have enough ammonia to be very effective in making wood pliable.

And Nick has a point about the application of heat onto well-soaked wood---.

So somewhere in all of this, may there be a safe and effective method---?

For planes, we make wing-tip and tail surface "bows" by soaking balsa strips in water for an hour or so, then cya one end tape it to the form and pull the inner strip around a form and tape it in position. Next apply white glue and pull the outer strip around the inner strip and tape in position., let glue dry naturally or heat form, etc., in microwave for a couple of minutes. This same method should work for mahogany strips, etc. maybe soaking in ammonia instead of water. Mahogany tends to buckle when making sharp bends as I recall when making railings.

Then there is the type of wood to be bent. I'm not seeing mahogany on this particular list.

Stock Selection
The U.S. Forest Service has tested 25 hardwood species for relative bending quality. The best 17 woods are shown here.
This ranking is the results from one evaluation; variation in the results can be expected from tree to tree and site to site.

White Oak (Best)
Hackberry
Red oak
Chestnut oak
Magnolia
Pecan
Black walnut
Hickory
Beech
Elm
Willow
Birch
Ash

Sweetgum

May I graciously suggest you purchase a copy of the "Wooden Runabout Restoration Guide" by Don Danenberg to learn how real boat builders bend wood, and build steaming equipment.

Mike
Classicwoodenboatmodels@yahoogroups.com

Originally Posted by steveciambrone

Myth???? Someone needs to tell the model airplane guys it can't be done, I built several model airplane tail structures by laminating thin strips of wood both balsa and spruce after being soaked in common ammonia. It works quite well, it may be dependent on the type of wood, but most woods for model use it works fine. I just took a length of pvc pipe and caped the bottom permantly and used a cap for the top, kept the stink to a minimum. Let is soak for a couple of hours and then bend the wood around a form, let it dry the soak again with thinned yellow glue, makes a very strong and light structure. Used the same process to bend the mohagany rub rail and cockpit coaming on my steam launch.

Sorry not a myth.

Steve

This 1/2" (!) half round in poplar was bent to shape after soaking in straight household ammonia... it was still a b1tch, but it bent. Now, maybe it would have bent just as easily after soaking in cold water for a couple hours, I dunno...

Originally Posted by Nederlander

May I graciously suggest you purchase a copy of the "Wooden Runabout Restoration Guide" by Don Danenberg to learn how real boat builders bend wood, and build steaming equipment.

Mike
Classicwoodenboatmodels@yahoogroups.com

Real boat builders don't want to buy ammonia in 50 gallon drums, when they can easily build a steamer. Hobbyists don't want to build steamers, when a PVC pipe with a pint of ammonia will do the job quite easily (apparently).

Originally Posted by patmat2350

This 1/2" (!) half round in poplar was bent to shape after soaking in straight household ammonia... it was still a b1tch, but it bent. Now, maybe it would have bent just as easily after soaking in cold water for a couple hours, I dunno...

Pat,
1/2" is very thick to bend, I would have tried laminated 1/2 x 1/8" strips, maybe even use a 1/4 x 1/8" strip on the outside and then shape after bending and glueing. Just a different way.

Steve

Originally Posted by Nederlander

May I graciously suggest you purchase a copy of the "Wooden Runabout Restoration Guide" by Don Danenberg to learn how real boat builders bend wood, and build steaming equipment.

Mike
Classicwoodenboatmodels@yahoogroups.com

I bought both volumes read 1/2 way though the first book and decided restoring a full size boat was not what I wanted to do, sounded good at first but too much going on with my life to put that much time into a project.

Steve

Hmmmm... Didn't expect to stir things up, but ok... anyway...

Back when I first heard about ammoniated bending of wood in modeling circles (years ago) I was skeptical as I had read the '81 Keenen article (still have it in my library) so I tried it on pine, balsa, mahogany and walnut using the strongest stuff I could find. Basically, my results were no better than warm water and definitely less than what could be accomplished with adequate steaming or very hot water soaking.

I have to admit that I was quite disappointed in this result as I knew you could literally tie wood into knots after proper treatment (visions of bowlines and clove hitches in walnut ). My current understanding is that there are two basic processes, one, the gaseous method already discussed, where the wood is exposed to a 100% ammonia atmosphere and one using pure liquid anhydrous ammonia. This would mean that the process must be carried out at temperatures below -29°F (Ammonia boiling point is -28.012 °F / −33.34 °C.) "Understanding wood: a craftsman's guide to wood technology By R. Bruce Hoadley" from the folks at Taunton Press, states that "Depending on the permeability of the species, treatment takes from one-half hour for 1/16-in veneers to many hours for ¾-in lumber."

Either way, the anhydrous ammonia technology is beyond most of us due to the temperatures involved, the danger of the material or handling the effluents. Maybe if I lived out in the boonies without neighbors, I might experiment for the gaseous method but as I live in a urban area, I don't want to anger my nice, long-suffering neighbors or attract the attention of the local environmental watchdogs. Even then though, the equipment investment would put me off, stainless isn't cheap and welding something to handle at least 10 atmospheres is more expensive still.

There are a number of bending processes out there, but most are either old... we hopefully know about them, or covered by patents, so no one who would know would be willing to discuss their trade secrets. I do know of one that uses hydrazine... we do NOT want to go there!!!!

Basically, it seems that the most reliable ways we have for plasticizing wood involve heating it whither by steam, indirect methods such as flame heated metal or heating pads or via microwave. The luthiers (Guild of American Luthiers) have come up with a number of tricks over the centuries and most of them are applicable to modeling as they are generally working on the same scale of thicknesses as we are.

An interesting bent wood solution, by the way, is called Bendywood. Interestingly, it's made without using chemicals - perfect for Europe (it's from Italy). I haven't obtained a sample, but the wood allegedly becomes permanently pliable.

One citation/article I would like to see, but haven't been able conveniently find a copy of as yet is:

Liquid Ammonia-Solvent Combinations in Wood Plasticization. Chemical Treatments
Conrad Schuerch, M. P. Burdick, Miroslav Mahdalik
I&EC Product Research and Development 1966 5 (2), 101-105

Just my obnoxious sense of curiosity...

Craig_C,
You are making this a lot harder than it is. Are you trying something in particular for a certain project? What are you trying to make?

Steve

It's just something that I got (overly?) interested in years ago while chasing down different techniques for modeling and crafts-type woodworking like bow making and lutherie.

As I said before... 'sense of curiosity.'

Originally Posted by patmat2350

Real boat builders don't want to buy ammonia in 50 gallon drums, when they can easily build a steamer. Hobbyists don't want to build steamers, when a PVC pipe with a pint of ammonia will do the job quite easily (apparently).

My wifes steam cleaner works really well! Just don't tell her I use it........

Hello Craig C. I'm glade you'r looking at TONY CHIBOUCAS's EDNA. Tony's 8 foot connie. Tony and I were long time friends. I worked with tony from the beging on the project, I alot of info regetfuly lost pictures in a fire a while back but have some notes and schetches, and A very Wonderful memery.Maybe I can help with you'r poject I like what you'r doing. I been boating since 50's and have had good fortune go to Spreckels Lake many times in past years. Email redcraftmodels@hotmail.com Regards Red.