What concentration of Butvar 76 should I use?

[Uncle Siphuncle]

The bag thing is more about drawing the air out for max coverage w min solution at ambient pressure.

 

W the the vacuum pot, a specimen sits immersed in solution, air drawn out by vacuum, so it outgasses, then when vacuum is released, solution is forced in deep by atmospheric pressure.

[Ptychodus04]

9 hours ago, KimTexan said:

What about the tink, clink sound of bones? Do modern bones make that sound? I’m thinking it must mean some degree of mineralization despite the look and weight seemingly like bone.

I've never tapped on a modern bone and listened for this sound. I usually only encounter modern bones when butchering and I'm not usually paying attention to that aspect of them. I would think a tinking sound would indicate some level of mineralization though.

[Ptychodus04]

14 hours ago, KimTexan said:

I think I’ve made the task more difficult for myself. 

 

Sorry for asking such elementary questions. I’m totally green. I truly appreciate you help and advice!

It only changes your process a bit. I really try to avoid water on all but the most stable of fossils.

 

Ask as many questions as needed. This is how you grow as a preparator. I wish I had this resource when I was starting out!

[Uncle Siphuncle]

3 hours ago, Ptychodus04 said:

I've never tapped on a modern bone and listened for this sound. I usually only encounter modern bones when butchering and I'm not usually paying attention to that aspect of them. I would think a tinking sound would indicate some level of mineralization though.

Keep in mind that lower extremities are the most dense bones to start with, due to weight bearing over small cross section.  So it might make sense to tap old vs new of same anatomical position for best reference.  Then again, I’m tone deaf.

[jpc]

Kim-

You've gotten some great advice here. I have nothing to add, except that since you live in Dallas, can you just open some windows and get good cross breeze going... voila, ventilation. 

 

Your description of digging in Wyoming is quite normal around here.  They say it builds character.  

[jpc]

Something else you should know is that if a bone is delicate and being held together primarily by Butvar/Vinac/etc, if you put more vinac/butvar on it, the acetone in it will first melt the previous butvar/vinac then your bone will fall apart and then the new product will set up.  An easy way to add more is to do it in very small amounts so that any redissolving is minimally effective.  

[KimTexan]

How do you know when you’ve put enough consolidant on a bone? I’m using B76.

@Ptychodus04 @RJB and @Uncle Siphuncle

The piece in general feels more stable. The edges around the breaks still feel fragile, but better than they were before starting. Granted they haven’t had time to fully set/dry.

 

I decided to start with the pelvis. It’s in a number of pieces.

On an aside note I believe it may have teeth/bite marks too. See last 2 pics. All pics are from one piece.

 

 

[Uncle Siphuncle]

I tend to superglue pieces together, then stabilize after, so as not to clutter break lines before joining.  I like tight joints.  If it feels stable you used enough.  Not an exact science.

[KimTexan]

47 minutes ago, Uncle Siphuncle said:

I tend to superglue pieces together, then stabilize after, so as not to clutter break lines before joining.  I like tight joints.  If it feels stable you used enough.  Not an exact science.

I have been having an issue with the cyanoacrylate not bonding like I am accustomed to. Normally I put it on and within 10-30 seconds or less it is set. That isn’t happening with these bones. I can hold it for a few minutes and it’s as if no glue is there. Everything else will stick to it, but not bone on bone. Some pieces I can put a clamp on it and 30 min later it is set. But it’s hard to do that with curves and where the bone is fragile.

I tried gluing the pelvis together. It would not stick. I even set still for 5 min holding it. No bond. The glue is setting wet on the surface. So it isn’t a matter of it being absorbed because the bones are dry and none is left to bond.

 

I have been torn about the gluing vs stabilizing first. Listening to what the others said about stabilizing first then gluing because the glue bond of your glue my be weakened. Acetone doesn’t do much to cyanoacrylate though. I too like the joint between pieces to be tight and am a bit concerned about it interfering.

 

Anyway, I wanted to see if stabilizing and then gluing would work.

 

Any thoughts on why the glue isn’t working? The bones are dry. There isn’t dust or dirt. I’m making sure the periosteum is alighted in case the porous part of the bone can’t bond.

 

[JohnJ]

Most likely the thin CA is wicking into the bone, leaving little on the edges for adhesion.  Try the gel type versions and see if you get better results. 

[Ptychodus04]

I like to stabilize then glue. I feel this provides a stronger base for the glue joint. I agree with @Uncle Siphuncle on the level of consolidation. If the piece isn’t falling apart, you’re probably good.

[KimTexan]

1 hour ago, JohnJ said:

Most likely the thin CA is wicking into the bone, leaving little on the edges for adhesion.  Try the gel type versions and see if you get better results. 

I don’t think it is wicking into the bone. On the pelvis it may have some, but not to the the degree it wouldn’t stick. On 2 different pieces there was excess glue sitting there at the joint. It’s a mystery to me. I can certainly try the medium thickness. One of the pieces was the neck of a rib. The periosteum there is thick and I think may be mineralized. It doesn’t seem porous. I had spinous processes do the same thing, but it was porous. 

Seems like I remember reading something about cyanoacrylate not working in an article by Amy Davidson from AMNH and her solution. 

 

36 minutes ago, Ptychodus04 said:

I like to stabilize then glue. I feel this provides a stronger base for the glue joint. 

I was wondering if that would help some. I’ll try it again tomorrow after it’s had time to off  gas a little.

I’ll see if I can find that reference by Any Davidson too.

[Ptychodus04]

Cyanoacrylate requires moisture for its chemical reaction. Often, partially mineralized bone is very hydrophilic so it is probably pulling all the moisture in the ends of the fossil towards the interior leaving the glue joint dryer than the Sahara. This would cause the glue not to set up. 

 

I ran ran into this while prepping fossils that had a lot of gypsum in them.

 

You have a couple of options to try. First, you can slightly dampen one side of the joint immediately before you stick the pieces together. This adds the required moisture. Second, you can get some activator that you spray on the joint after you join the pieces. This can sometimes turn a fossil green so caution is advised in its use. Lastly, you can switch to a Butvar glue. It has drawbacks, mostly in drying time, but it doesn’t have any chemical reaction so it is very simple.

[KimTexan]

If it continues to be a problem my next plan is to use Paraloid b72 as an adhesive. I’m not sure if the recipe for that application though. Gram paraloid to ml acetone or general consistency. Is it thick like toothpaste more/less? 

It’s weird because some bones glued and stuck together like I’d expect to with cyanoacrylate. Others not. No clue what the difference was. I plan to play with it tonight again.

Maybe it is some mineral content in the bone. Some bones have a texture that is different somehow. It seems less porous, more dense and smooth than the others that do glue.

[Ptychodus04]

47 minutes ago, KimTexan said:

If it continues to be a problem my next plan is to use Paraloid b72 as an adhesive. I’m not sure if the recipe for that application though. Gram paraloid to ml acetone or general consistency. Is it thick like toothpaste more/less? 

It’s weird because some bones glued and stuck together like I’d expect to with cyanoacrylate. Others not. No clue what the difference was. I plan to play with it tonight again.

Maybe it is some mineral content in the bone. Some bones have a texture that is different somehow. It seems less porous, more dense and smooth than the others that do glue.

 

I'd stick with the Butvar for the glue since you're using it as your stabilizer. It will hold well. As for the mixture, it is all by feel so to speak. There's no real ratio that you need to use for any of this (just like how much is needed to consolidate). Preparation is a very inexact science. I typically mix my glue (I'm still using Vinac/McGean B15 for another month or so) to a consistency somewhere just thicker than honey. This way, it will still ooze a little into the joint but has less of a tendency to run all over the place. I apply it with a popsicle stick.

 

Now comes the fun part. You have to clamp, strap, tape, or prop the bone in such a way that the joint is completely immobile for several days. It takes a long time for the acetone to out-gas from a thick solution. I have employed small ratchet straps with good results. The form to the irregular shape of the bone and provide good tension to hold the joint. The best part of this method is that you can easily remove the glue with acetone if something goes sideways on you and start over.

[KimTexan]

Thank you. That’s helpful to know the consistency.

My understanding, from a paper I read was that B76 was not as good as an adhesive as paraloid B72. So that’s why I was considering going that route. 

 

Gluing the pelvis was a bust again. The cyanoacrylate isn’t bonding. All I’m doing is layering it on it hardens, but doesn’t bond and now there is a gap at the joint so it isn’t tight. Dang it. Live and learn.

 

I went back and found the reference from Amy Davidson on a case study of very soft porous bone in oviraptors from the Gobi Desert or Mongoli. She said cyanoacrylate didn’t work with them. It just solidified without forming a bond.

 

I arranged to go visit Lori Gouge Feb. 15. She is at Weatherford College where they are working on a mammoth prep. She said to bring some of my stuff and she’d give me ideas on how to prep. I have fragile good size fragments of the skull that came off. That is where I need the most help. So I’ll take those with some other stuff and hopefully get some ideas and get to help with the mammoth prep too.

 

[Ptychodus04]

9 hours ago, KimTexan said:

My understanding, from a paper I read was that B76 was not as good as an adhesive as paraloid B72. So that’s why I was considering going that route. 

I believe Paraloid is generally stronger than Butvar in most applications but Butvar will hold just fine.

[RJB]

10 hours ago, KimTexan said:

luing the pelvis was a bust again. The cyanoacrylate isn’t bonding. All I’m doing is layering it on it hardens, but doesn’t bond and now there is a gap at the joint so it isn’t tight. Dang it. Live and learn

Must be some real spoungy bone?   Can I ask what thickness/viscosity of super glue you are using.   Also, those bit marks look very interesting!

 

RB

[KimTexan]

14 hours ago, RJB said:

Must be some real spoungy bone?   Can I ask what thickness/viscosity of super glue you are using.   Also, those bit marks look very interesting!

 

RB

The periosteum isn’t spongy. I think some of the periosteum could be mineralized. It seems so dense. Inside the bones is very porous.

I use the thin. I just ordered some thicker stuff to try though.

My B76 must have been too thick. It seemed to develop surface tension in the porous bone and not run down into the bone. You can see it pick below.

 

This is part of the pelvis I treated with B76, but I don’t think it penetrated beyond the surface or periosteum.

[JohnJ]

A small tube of super glue gel can be picked up for a few dollars at almost any local supermarket. I've used it for years on bone breaks of varying density when the thin formula didn't have enough solid surface for an effective bond.

[KimTexan]

5 hours ago, JohnJ said:

A small tube of super glue gel can be picked up for a few dollars at almost any local supermarket. I've used it for years on bone breaks of varying density when the thin formula didn't have enough solid surface for an effective bond.

It doesn’t seem to be a solid surface issue though. The thickness of the periosteum alone should be enough. One rib piece broken at the neck of the rib is sufficiently thick and solid, but no bond would happen. It seems like something is preventing the reaction from happening. I don’t know the chemistry of it well enough to know what inhibitors there are that could do that. What could interrupt the chemical reaction?

There is something about the bone composition that is the issue. It is weird.

 

That said a thicker glue will likely work.

[RJB]

1 hour ago, KimTexan said:

 

That said a thicker glue will likely work.

Good luck Kim.  Always nice when something works and there are no question marks running around in ones head.

 

RB

[Ptychodus04]

This really sounds like a classic low moisture issue. I’ve had bones outright refuse to bond after hours of contact with cyanoacrylate. I wiped off the glue, took a damp sponge and patted one surface just enough to slightly dampen the bone, reapplied glue to the other side, presses them together, and got an “instant” bond (a few seconds).

 

If the glue is not being drawn into the bone, try this method.

[KimTexan]

12 hours ago, Ptychodus04 said:

This really sounds like a classic low moisture issue. I’ve had bones outright refuse to bond after hours of contact with cyanoacrylate. I wiped off the glue, took a damp sponge and patted one surface just enough to slightly dampen the bone, reapplied glue to the other side, presses them together, and got an “instant” bond (a few seconds).

 

If the glue is not being drawn into the bone, try this method.

I actually did try it with the very first bone that didn’t glue together, but I can attempt another one.

 

I purchased a new bottle of cyanoacrylate that came with 10 fine replacement tips. I’m wondering if maybe it is the brand. Maybe the formulation is different.

I got a new bottle of the stuff I had been using. I get 8 oz of Bob Smith brand of cyanoacrylate for $22. I will give it a test run on a bone this evening.

 

I have several different pieces that I’ve basically messed up so that if I try to glue them now the old layer of CA is preventing the join from being a good fit. I’m not sure there is anything I can do at this point. One of them I sanded down to try to get it to look better, but it was still messy looking. I clamped it and then it set.

[Ptychodus04]

25 minutes ago, KimTexan said:

 

I have several different pieces that I’ve basically messed up so that if I try to glue them now the old layer of CA is preventing the join from being a good fit. I’m not sure there is anything I can do at this point. One of them I sanded down to try to get it to look better, but it was still messy looking. I clamped it and then it set.

Try picking it off with a fine dental pick. Often, you can get it to peel off the bone.

 

You can also apply acetone to it to soften the glue and pick it off.