How to soften & bend Balsa

When you bend balsa sheet parts with ammonia cleaner, does it need to be submersed or is a good soaking enough? I tried spraying some ammonia cleaner on a balsa sheet part, but it doesn’t feel like it soaked in; it just wet the surface some and didn’t soak all the way through.

You could also put the part in a plastic bag ( like a bread bag) and spray in some more ammonia cleaner before closng the end.

How long should the wood soak in or be exposed to the ammonia cleaner?

Then, when forming it on a curved surface, what does the tape do? will any kind of band (like an excersize band or a nylon stocking) be enough to hold it on the surface?

After that, you just let the whole thing set in a well-ventilated place until the part becomes dry…

Is there any difference in the procedure for forming thin ( 1/32 or 1/64) ply?


I made up some thin strips that i was arginalyl going to use on my soling one meter mast to hold the sail. and after cutting the strips (1/64 bitch ply) and soaking overnight in just water. i was able to get the strip to wrap around a 1/8" diameter carbon rod with no splintering or breaking…I then used a office alligator clip to hold the ends together while wrapped around the rod until it dried… But I ended up not using them as it was too hard to cut a slit in the mast for them that was straight…

I used steam for bending pieces of hardwood for making chairs. It only took about 30 minutes or so, instead of overnight. IMO, if you let ply soak overnight, wouldn’t you expect it to delaminate instead of soften?


maybe so, but it did not…go figure…

Thew most incredible thing I’ve ever heard about the thin ply is that “It doesn’t exist” from the guy at the woodworking store. He claimed that you can’t get anything thinner than 1/8 inch because “the layers would be paper-thin, and it would tear!” :confused:

Google for “Bending plywood”

its thin and it will tear…like paper…its just like a veneer.

Veneers split instead of tear. It probably looks like tearing to you.

there was not much help using a search engine relevant to model boats for bending lite ply or balsa.

Well, This is the how-to section, and new people would be looking here for help on how to do things like bending wood. There is some mention of it in certain places, but a formal explanation would be of the most help to beginners.

I use anywhere from 10-50% ammonia mixed with water.

Lighter, softer woods like balsa, I use the lower strength ,and the upper end for harder woods.

Soaking time depends on the hardness of the wood and the strength of the ammonia.

I like to use a section of PVC pipe with end caps for soaking stripwood and a plastic tray for sheets , though you could just use larger diameter pvc pipe.

Take the soaked wood and hold it in place( rubber band, clips, pins) on your form till dry.

Most hobby plywood doesnt get soft when soaked in ammonia because of the glue. Ammoinia softens the fibers of the wood ,but the glue is not softend.

I use heat( heat gun) to bend thin ply 1/64, 1/32. I “wrap” the ply around a form( as much as it will bend) and then heat it while pulling or pushing it into shape.

Don’t forget to spray both sides.


What are you doing that you need to bend the balsa? what grade balsa are you using? Competition grade balsa is really bendy.


Try competition grade balsa, is not as dense or as stiff as hobby store balsa.

Mudhenk said in another topic that all balsa needs to be prebent.

That depends what you plan to do with it. If you need to make 90 degree bends then yea your have to steam it, but if all your doing is sheeting/planking a hull I see no need to steam it.

We’re not usng steam to bend balsa for Footies; it’s too radical or involved. Instead Ammonia cleaner is sprayed onto the balsa, alowed to soak in some, and then the part is shaped on a curved surface like a pot, until it dries.

relevant topics include Cobra and Tanto.