I’m working on a piece in cocobolo– clear on the acetone wipe procedure immediately before gluing, but I wanted to ask if there’s a concensus about whether to use polyurethane glue or epoxy (or something else). Anyone have experience with these? Thanks in advance.
John Casteen
www.fernhillfurniture.com
Replies
John,
I've made a few things with cocobolo and just used yellow glue (Titebond II) after making some test joints with scrap. They've held for three or four years with no sign of weakness and they're just butt joints with no acetone or other wipes beforehand. I know this is contrary to other reports, but it's worked OK for me. Right now I have three jewelry boxes in the works using cocobolo and plan to joint them the same way, so if you want to wait a couple of days I'll give you a fresh report. Otherwise, why not do a glue test and see for yourself?
Jim
I use clear, 12 hr cure, 2 part epoxy. The crack generally disappears never to be seen again. A heat lamp will cut the cure time down to a couple of hours.
PlaneWood by Mike_in_Katy
PlaneWood
John,
Never having had much luck with Cocobolo, I'm interested to hear how you finish it. I've used Tung oil and Linseed oil. Nothing else ever seemed to stay on the wood or even to harden (dry) to any extent. Nothing I've ever put on it, left it as beautiful as in its raw state. It just seemed to dull it.
Rich
Oil base finishes turn cocobolo red-orange. Shellac turns it purple!! Water base poly will change it very little, but I expect in time it will turn slowly red orange whatever the finish. Good luck.
John, Goldhiller, Duke,
I was all out of Shellac. ALL OUT OF SHELLAC! (oops, sorry)
So I decided to try spray lacquer, but I have no spray equipment so I went to that purveyor of fine finishes, Ace Hardware and bought the REAL cheap stuff. Lacquer in a spray can. Sprayed my practice piece of Cocobolo, 2 coats. Rubbed it out real fine with steel wool, white nylon and a soft cloth.
The results in ONE WORD, Beautiful! Gorgeous, Magnificent
Go figure. Total Previous Failure with Cocobolo 'till I squirt it with rot-gut Ace Hardware lacquer! Thanks for the advice! I'm a Cocobolo-finishing fiend, now.
Rich
Rich:
Have you tried the BEALL system of buffing compounds? I've made several hand planes and use this system to polish them. Woodcraft and others carry the Beall system as a kit or individual pieces.
Roger
John,
I've got pieces here in the house that were made with cocobolo in the late 70's via thorough acetone wipe and Titebond I (Titebond II did not exist)and no joint has failed yet.
Thanks. This is what I needed. I appreciate everyone's advice.
As far as finishing cocobolo, what I've done in the past with it (carvings in one shop, a tabletop in another) was finished either with shellac or nitrocellulose lacquer. I have been told that varnish would have adhesion problems and oil would muddy the grain, so I haven't tried either one; I like the shellac best (I used the lighter stuff) and would use it on anything that isn't going in a bar or a bathroom.
Someone did just buy a shellacked piece of mine through a gallery and stick it in a bathroom, or so I was told. Cross your fingers.John Casteen
http://www.fernhillfurniture.com
John,
I haven't worked any cocobolo for a few years now nor have I had need to finish any recently. I think cocobolo is probably at its best aesthetically with no finish, but sometimes this just isn't appropriate. You're probably aware that a waxy finish will develop if you simply rub the surface with a cloth. Cocobola doesn't need much of a finish to just survive in the world, one of it's principle uses historically being for cutlery handles where it is exposed to soaking in soapy water, but some sort of finish is desirable if we're going to prevent dirt from lodging in the wood when we use it for furniture and the like. The shellac approach sounds fine to me, but if you need/desire something that has a bit more durability and water resistance, you might consider making that first coat of finish with de-waxed shellac, which would allow you to follow with a coating chosen from among various other finishes including polyurethane, should the situation call for protection of that nature. I'd recommend doing that acetone wipe prior to finishing, as well.
Thanks for the finishing tips guys. John, you're right about oil muddying Cocobolo's appearance.
Think I'll try another Cocobolo project. Hmmm . . . where did I put that paperwork to take out a second mortgage?
Rich
Hi John, I'm new to this forum, but have been building all wood composite longbow's for a little while. I realize this isn't typical furniture application, but may shed some light on the possibilities.
Cocobolo as well as other hard, dense woods like Mexican Kingwood are used quite a bit in bow building for the handle or "riser" section of the bow. Their primary attribute in this application is relatively heavy mass weight as compared to the limb wood. The extra weight helps stabilize the bow when shooting, the beautiful grain is icing on the cake.
As for gluing, cocobolo is attached to the main piece of limb wood like hickory or osage using either URAC 185, Titebond II or Smooth-On 2 part epoxy. URAC or epoxy are generally the favorites. Before gluing the joint , both pieces of wood are lightly scuffed with a toothing plane and then wiped with acetone, then clamped together to cure. Some use 40 grit sandpaper instead of a toothing plane for a cleaner glue line. If the asthetics of the glue line are not an issue, go with the a toothing plane. From personal and other bowyers experience, either of these glues hold up quite well. If you can visualize the arch of a drawn bow at the handle section, you can imagine the stress as the limbs flex downward on the handle as well as the resultant shock as the limbs recover once the arrow is released. Granted some of the adhesion "magic" is attributed to the bowyers skill in crafting the limbs so the amount of flex through the handle area is just right, but it's as demanding a wood-to-wood glue joint as you're likely to find anywhere.
Some of the others touched on finishing issues too. Again I'll toss in some application from bow building. About the most popular and durable finish is a catalyzed varnish called Fullerplast, which works very well on oily wood like cocobolo as long as you clean with acetone before applying. It's as water proof, UV tolerant and scuff resistent as anything I've seen. It fills grain very well and dries to the touch in about 20 minutes. It can be wet sanded and polished for an extremely high gloss finish. However most bow builders buff it down with #0000 steel wool for a satin finish to reduce game spooking glare in the field. At roughly $35 a qt, its expensive, but very tough stuff for sure.
I hope this helps. - Eric
Eric,
Thanks. This is a big help-- the application I've got is an edge joint used in the load-bearing support of a bench, but nothing like the loads you're talking about. I'm sure your method will be more than enough for what I need to do.
The finishing advice is helpful, too-- thanks also to whoever suggested lacquer. I've used that and a catalyzed conversion varnish that I think is similar to Fullerplast. Someone else recommended a stiff rubdown with no finish, which so far in my shop seems to be pretty nice. I've had success with shellac in the past, and that's probably what I'll use in this case.
It should be a couple months before I get the bench built, photographed and uploaded. Maybe I'll send up a flare here to let you see the results. Thanks again for the advice.John Casteen
http://www.fernhillfurniture.com
Hello Eric,
I am interested in building a longbow with my son and have a couple of questions:
Is white Ash a suitable wood for a longbow?
Where can I find info on building a longbow? Can you
recommend a good book on the subject?Thanks,
Wil
Hey Wil, Eric,I can't believe I missed this thread earlier. I thought I was the only guy building longbows on this forum. I'm glad to hear that I have company.Wil,Without a doubt, the most complete work on building self bows is "The Traditional Bowyer's Bible" (TBB for short). It's in three volumes, and has more information than you'll need to get started. Another good book that's been around for many years is "The Flat Bow". It's a lot cheaper investment, and might be a good starter for you. I started with it a long time ago.Ash makes a good self bow, but if you're making a lumber bow, be sure to chose your boards carefully. You want to avoid any grain runout, for the entire length of the bow if possible, particularly from back to belly. You have some leeway however because the bow narrows to the tips; sometimes you can avoid the runout present in the stock.At the yard I visit, I would guess that less than one board in twenty has good enough grain to take a chance on.Eric, Sorry to step on your thread, but I'm excited to hear from another bowyer. Are your bows mostly modern, or primitive? I recently finished my first modern bow, a 68" R/D, 45@28, fiddleback maple and red elm core, with a cocobolo riser. It's a real sweet shooter, and I want to get started on another, but I have two bamboo backed primitive bows to finish first. My last, was bamboo backed jatoba R/D, 64ntn, 60@28, about two weeks ago. If you search the gallery, you'll find it.Tom
Hi Tom,I haven't built a bow yet so I am not familiar with the terms
Self bow and Lumber Bow, can you explain?
In the meantime I am going to look for the books you mentioned.
I have a large source of incredibly straight grained ash and thought I could make a bow by slicing it thin and laminating the strips.Thanks,
Wil
Hey Wil,A self bow is a bow shaped from one stave of wood, or perhaps two billets glued together at the handle.A lumber bow is a bow made from sawn lumber, as opposed to a split stave. Obviously a split stave will have problems with straightness, and lumber has problems with runout.Usually, it's a good idea to start out with a lumber bow, just because a well seasoned split stave is more expensive. On the other hand, you're more likely to have success with a stave, because there's no runout. It really depends on how much money you have, what wood's available, and how you like to work.Another good book is "The Bent Stick" by Paul Comstock, a contributing author to the TBBI would encourage you to make a self bow first, before laminating up one. You will learn the skill of tillering without complications, or too much investment in the event of failure. Failures are part of bowmaking, but they do teach you where you went wrong. There are a number of different techniques for laminating bows, and pre stressing the limbs in the process. Laminating also allows you to make use of special properties of different components like bamboo, but nearly always complicates the way a bow is brought out of the wood. Best to start simpley.Tom
Thanks for the insight Tom,
Wil
Hey Wil,Sorry to drag on, but I forgot to tell you of a valuable resource athttp://www.primitivearcher.comIt's a subscription website, so you'll have to pay up to log on, but you'll find the world's best bowyers of primitive bows there, from all over the world. They also have a beginers forum where they all chip in with free advice. They're a great help, and a great bunch of guys. I log on there as 'fishman'.Tom
Edited 4/21/2005 6:03 pm ET by tms
I have an old long bow (a self bow) that my father made out of Osage Orange about 70 years ago. It has been in the attic for many years.
Do you think it would be safe to string and shoot, or should I just display it?
Sorry for hijacking the thread, but I wanted an expert opinion.
Regards,
Dan
Hey Dan,Without knowing a little more about the bow, it's hard to say. How was the bow stored? What's the length and draw weight? What was your father's draw length?Theoretically, if the bow was stored well (not dessicated), and it's within reasonable length and draw weight for a hunting or target bow (not a flight, or maximum performance bow), you should be able to brace it and shoot it.It's important to know what draw length the bow was made to shoot, particularly if it's an older bow with a history of use. The wood will definitely take a memory of the draw length, and over time will become less tolerant of an over draw. That is probably why most older bows bite the dust, is overdraw by someone who never shot it when it was young.If you want to brace it, use a low brace height at first, say 5". Unless you know the specified brace height. Use a bow stringer. Then gently exercise the bow up to full draw. Never dry fire the bow, or you will likely have firewood. For the same reason, use a new string. Heavy arrows are more gentle to the bow than light arrows. I would stick to arrows around 10 grains per pound of draw weight.If the bow is backed with sinew, or rawhide, you have added protection against failure. If the bow makes any noise at all when bending, retire it. The exception is a sinewed bow, they will make the most frightening noises when the sinew is over dry, but seem to work safely all the same. If it's an heirloom, then only you can decide if it's worth the risk.My feeling is that all bows have a life span, and that if it's not spent shooting, then it's a wasted life.Good luck,
Tom
Edited 4/22/2005 2:10 pm ET by tms
Thank you for responding. The bow is longbow style about 5 1/2 feet long. I shot it in my teens - about 35 years ago. I recall the draw weight in the 45 - 50# range. Mt Dad and I are about the same height - 6', so our draws are probably similar. He taught me to draw to the corner of my eye.
The attic gets very hot, but the relative humidity is seldom below 50%, usually in the 70-80% range.
The bow is a solid length of bois d'arc, with a walnut grip wrapped in leather. There is no backing of any sort. The cross-section at the thickest part is a "D" shape.
Thanks again.
Dan
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