Primitive Archer
Main Discussion Area => Bows => Topic started by: IdahoMatt on June 17, 2013, 12:30:43 am
-
I have just tried my hand at steam bending, because I was not getting the results that I wanted with dry heat. I left the stave under tin foil, over a pot of boiling water for about an hour, and got the bend that I was looking for..... Only to see the next day that I had little drying checks. I left the bow clamped for about twenty four hours... What should I do to stop this from happening in the future and, can the bow that I bent be saved?
P.s. the stave was locust and was cut the spring before last, split and ends sealed, with bark left on the back... :o
-
Ive never had that problem but from what I hear steam bending actually drys your wood out more
-
i can attest to that, with my mulberry that i'm making, the wood seems very dry for a couple days in the spots i steam.
-
i can attest to that, with my mulberry that i'm making, the wood seems very dry for a couple days in the spots i steam.
Did your bow have small checks where the steam hit the wood after the couple of days?
-
i have 1 or 2 1mm cracks after 3 steaming attempts so it's still a tad lopsided but will have to do.
-
Those checks are caused by the wet wood on the outside drying faster than the wood underneath. I get really bad checks when I steam bend dry juniper. Sometimes it's the only way to get the right amount of bend, though.
You need to make sure that the wood dries VERY slowly after steaming. I think PatB coats the wood with shellac before steaming so the water can't get to the wood in the first place. I hit the wood with a coat of beeswax or pine tar after steaming. Sometimes it works, sometimes it doesn't. If all else fails I wrap the area with rawhide.
The rule "dry wood likes dry heat and wet wood like wet heat" applies here but I assume we are not able to obtain wet (green) wood.
-
I usually don't steam dry wood ,but always seal any wood I plan on steaming,it will help with the checks even when using dry heat. :) I get it floor tillered and the back slick as I want it and sealed before I start heat or steam correcting,leave it that way until I am finished in case it needs more along the way. :)
Pappy
-
Thanks guys. I wouldn't have thought of that. What would you recommend for a sealer? Is the bow I got the checks on okay?
-
Thanks guys. I wouldn't have thought of that. What would you recommend for a sealer? Is the bow I got the checks on okay?
It might be depending on how bad they are. How large are the cracks, and do they run off the edge or do they stay within the boundaries of the bow? Longitudinal cracks can be worked with. Fill them up with super glue and make sure that none of them run off the edge of your bow.
-
I think PatB coats the wood with shellac before steaming so the water can't get to the wood in the first place.
I thought he did this because it would allow you to use the heat that steam brings without the moisture penetration. I had not considered that it would control the release of moisture after the process
Either way, I've followed his example and have not experienced the checks you are describing. I have a steam generator and have had success steaming the whole bow at once:
(http://i1139.photobucket.com/albums/n558/paddlermutt/IMAG0662.jpg) (http://s1139.photobucket.com/user/paddlermutt/media/IMAG0662.jpg.html)
I spray on 3 coats of shellac and steam in a tube.
-
The checks are very small, but clustered, no runoffs. And shellac good to know :)
Thanks again this site has saved me so much trial and error so far. It is truly invaluable ;D
I'll try to upload some photos of the bow if it becomes one.
-
I think PatB coats the wood with shellac before steaming so the water can't get to the wood in the first place.
I thought he did this because it would allow you to use the heat that steam brings without the moisture penetration.
Yeah, he puts on the shellac before steaming. Personally, I coat the wood after steaming. Sorry, I just started rambling and mixed the two techniques together in the same breath... :-[
-
I think PatB coats the wood with shellac before steaming so the water can't get to the wood in the first place.
I thought he did this because it would allow you to use the heat that steam brings without the moisture penetration. I had not considered that it would control the release of moisture after the process
Either way, I've followed his example and have not experienced the checks you are describing. I have a steam generator and have had success steaming the whole bow at once:
(http://i1139.photobucket.com/albums/n558/paddlermutt/IMAG0662.jpg) (http://s1139.photobucket.com/user/paddlermutt/media/IMAG0662.jpg.html)
I spray on 3 coats of shellac and steam in a tube.
The steam will penetrate the shellac and moisture will get in. Otherwise it would be just the same as applying dry heat. The shellac would just slow it down to a more stable rate.
-
I have steamed dry wood several times. I always put shellac or even laquer on the bow first. So far no bad results.
-
I usually don't steam dry wood ,but always seal any wood I plan on steaming,it will help with the checks even when using dry heat. :) I get it floor tillered and the back slick as I want it and sealed before I start heat or steam correcting,leave it that way until I am finished in case it needs more along the way. :)
Pappy
That's weird never heard of that, but it seems you mine as well use dry heat if you do it like that
-
I have no checks on the belly or sides just the back. Should I just coat the back as if green and bark removed, then try steaming or coat the whole thing?
-
Joec123able,if you use dry heat on wet/green wood before steaming it will check
a lot of the times even if sealed. Seal and Steam it first and you can use dry heat after that. :) I don't steam a lot because I don't use wet/green wood very often.Got plenty of seasoned wood to work with so usually use dry heat. :) I am not saying if you don't seal it, or steam dry wood or dry heat wet wood it will alway check but it has happened enough to me [and I have steamed and dry heated a lot of wood]that it's not worth the chance so I seal it always. :)
Pappy
-
Thanks Pappy. I live in the desert, it is pretty dry as you would expect. At the hottest part of the day the R.H. gets down to around 15%. Would you just coat the back with the sealer?
-
Yes I would,like I said it's not going to hurt to seal it so I seal them all and it can make the difference between checking and not checking ,so to me it's not much trouble so I do them all,either way. :) I just keep cheap wood glue mixed up [cut with a small amout of water] in a coffee can with a lid on it and a brush inside takes a couple of minutes to seal one. :) I know some will argue that you don't need to and I agree you don't always need to but for no more trouble than it is I just seal them,I hate checks,they don't usually hurt the bow as has been said if the don't run off but they don't look good to me and I will usually want co cover them up with a skin or something,I like skins but don't want to have to skin one because of my laziness. :)
Pappy
-
Good point. Thanks you again, I'll post pics soon just got one broken in, not the one in question. ::)
In my dry climate do you think I could use dry heat with success? P.S. that will be the last question :)
-
I would think yes,if the Moisture content in the wood is down,don't have that problem in Tennessee,humidity is 75 to 90 all spring and summer and sometimes into the late fall. ;) :)
Pappy