Pre-soaking binding material
It's time to get on with finishing one of the original batch of guitars that I started making from the Georgia Luthier plans. The bodies were assembled months ago and the binding channels cut when I had the router set up to do the Maccaferris. This part of the process isn't my favourite as I have found it difficult to get the wood to bend with out a fairly high degree of scorching and burning rosewood really stinks! I have played around with the temperature and using wet cloth and a water spray to generate some steam but I wondered if pre-soaking the binding strips would make bending them easier and reduce the need for repeated spraying and wetting during the bending process. As the material I am using is rosewood (not very absorbent at the best of times) I thought that it would help if I put them a water filled vacuum chamber, the idea being that the vacuum would suck all of the air out of the wood which would then be replaced with water when the vacuum was released. I made the chamber out of a piece of Hep2O 22mm plumbing pipe (other brands are available!), plugged one end and fashioned a connection for my vacuum tube at the other. The bindings strips were placed inside, the pipe filled with water and a small block of badly fitting foam stuck in the end to keep the strips submerged. The end was then sealed and the pump turned on. I had put a moisture trap in the vacuum line and some water did get sucked through to it indicating that air was being removed from the wood causing the water to bubble up. I left the strips in for a couple of hours and then turned off the pump and allowed the vacuum level to slowly dissipate and, after removing and drying the strips I reweighed them which showed that they had absorbed 4cc of water into 65.5cc of wood. I am still not sure if this seems like a lot or not but they certainly feel more flexible and I will be bending them shortly so I'll let you know. I will also do a control test over the weekend with the same set up but without the vacuum to determine if it had any effect on the absorption of the water.
Ok. It certainly made it easier to bend the bindings having been pre-soaked and the non-vacuum test absorbed 4g of water into 66cc of wood so pretty much the same albeit left submerged for quite a lot longer ie overnight.
Clearly a single run of each test type isn't going to provide results reliable enough to be published in New Scientist but I think it indicates that it may be a useful process with or without the vacuum, especially as a means to reduce the likelihood of scorching. I've got some more bindings to do this coming weekend so I'll have another go with a different species.
Great to see some experimenting going on - Hope it works!
Hmm - If not, and you still want to avoid using a standard bending iron: you could maybe try laminating some binding like you did with the lining - what do you think? What are you currently using to bend on? Are you planning to steam vacuum it to make it floppy and then vacuum press bag it?
FYI: a spritz of water is all that is usually needed for bending the binding the normal way - sometimes soaking for too long can make bending harder especially highly figured flamed maple and similar.
Measure twice, cut once...