Repair of Broken Bones Technique
When you are planning to repair a bone-to-bone fracture, a careful examination of the break is necessary. Small parts of the broken surface often fall sideways or misalign themselves with the opposing surface, preventing a quality matched rejoining. Also, internally a fossil can be porous and weak. Here is what to do: Brush the opposing surfaces to get rid of any loose particles, and without any adhesive, make a test rejoining. If you have an object that prevents a match, remove it. When you're ready to bond, the adhesive will fill in and restore strength. A little trick I like to do is mark the matched, unbonded pieces together with a pencil before I apply the adhesive. It helps me get the darn things back into alignment before the adhesive sets.
Apply Paleo Bond Penetrant and Stabilizer (P&S) to both opposing surfaces. Let it soak in for several seconds, (If the bond is very punky and porous, apply more P&S until it won't take any more.) If the Penetrant and Stabilizer remains liquid on the surface, join the two parts and you will get an excellent bond. If the Penetrant and Stabilizer has completely soaked in, there will not be enough adhesive on the surface to get a good bond.
If the pieces don't fit together perfectly, or if there appears to be no wet Penetrant and Stabilizer, or if you need some degree of gap filling, apply a higher viscosity adhesive such as Paleo Bond PB 100 to one surface. Join the opposing surfaces, hold together, and wait a few seconds for the bond to occur. If you are in the "let's get it done now!" frame of mind, do this: Spray the PB 304 Activator on only one surface. VERY IMPORTANT!! Apply the PB 100 on the other surface. Now, VERY CAREFULLY join the two. You will have an instant bond. The squeeze-out can be wiped off quickly, Or if You want to harden the squeeze-out for later removal, spray it with the PB 304.
Stabilizing and Strengthening a Fossil Bone
If you are working with a fossil that has not been silicafied, it is likely that the bone marrow is very porous, fragile, and in some cases, internally pyritized. The outer surface can be cracked and frustratingly brittle. By pouring an exterior sealant such as Glyptol (which is nothing but Nitrocellous varnish that dates back to the 1910 era), you have sealed the surface, but you have not done a darn thing to the interior. If you are careful, the cocoon of burlap and plaster of paris will get the fossil back to the prep lab. Then comes the unwrapping and the possibility of further damage to the fragile bone.
QUESTION: Why not harden the fossil bone interior in the field?
Penetrant and Stabilizer as a Primer for other Adhesives
Whenever you bond two porous or fragile substrates together, the weakest part of the bond is at the glue line. If you have used a non-penetrating adhesive, it has penetrated only a few thousandths of a millimeter. Where the penetration stops, it can break again. SOLUTION: Prime the two surfaces with P&S. You will now have a substantially wider and stronger area that will take additional higher viscosity adhesives.
Why Different Viscosity (cps) Adhesives?
Paleo Bond adhesives range in thickness (cps) from 2 cps to 80,000 cps, much the same as water compared to Vaseline respectively. Remember, the higher the cps number, the thicker the adhesive. Sometimes two opposing surfaces just don't match up, either the bones have shrunk or the surfaces are damaged and there is no mate. You need a thicker adhesive to fill in the error.
In the repairing of cracks, different viscosity's are required. If it's a hairline crack, use the P&S. If it's wider, use the PB 40, PB 100, PB 750 or PB 1500 adhesives. If it's serious gap time, use the Jurassic Gel. Any excessive adhesive exposed to the outside world can be sprayed with activator. It will surface harden instantly. The internal hardening and strength build-up will continue for many more hours.