Next Steps for Triceratops Rib Prep

[Opabinia Blues]

In May I found a nice ceratopsid rib out in the Hell Creek Formation, kicking off my first opportunity to work on prep for a large dinosaur bone. The bone was very brittle, and had to be extracted in multiple pieces.

 

I have just finished the first “phase” of preparation: bulk matrix removal and cleaning of each piece and gluing everything back together. Unfortunately, my sister’s puppy (who’s super curious and loves to carry stuff around) managed to pull a piece of rib off my prep bench, and by the time we realized the dog had it part of the piece had crumbled, so it no longer fit perfectly with the rest of the rib. I had to use Paleosculp to bridge the gap.

 

 

I’ve done about as much as is in my wheelhouse. I am purchasing a used air abrasive unit soon, so I will be able to continue working on this piece (and others). I figure the next steps are air abrasive work, gap and crack fill with Paleosculp, and finding a way to attach the articular facet (both pieces are rounded in this area so there’s no clear location to bring them together for gluing - will have to sculpt with epoxy). I might also have to do some painting if the color match with the Paleosculp isn’t close after I air abrade.

 

Basically, I’m just looking to see if my general thought process here is correct and if anyone has any wisdom to share. I appreciate any feedback! :)

[SPrice]

Bummer about the over enthusiastic canine fossil de-prepper.  But your rib bone is looking really good so far.

[Alex S.]

Looks great so far. What's the scale for this rib? Your thought process seems on track. Id love to see close ups of the bone. It looks like there's only a few spots the need air abrasion. What unit are you buying?

[Opabinia Blues]

14 hours ago, Alex S. said:

Looks great so far. What's the scale for this rib? Your thought process seems on track. Id love to see close ups of the bone. It looks like there's only a few spots the need air abrasion. What unit are you buying?

The rib is ~60 cm long measured on a straight line between either end, not including the articular facet. The abrasive unit is a Vaniman, but I don’t remember the exact model off the top of my head.

 

Here’s an up-close of some of the sections of bone I think need abrasive work:

[hadrosauridae]

Looking good so far!  I would wait until you  have it soda blasted clean before adding the epoxy.  It doesnt have to match perfectly, just be somewhere close.  Once its fully cleaned and consolidated with Butvar or Paraloid, start with filling all the cracks first, then let that cure before repairing the gap.  I recommend doing that in 3 stages.  First is to make a center core of epoxy, it shouldnt fill all the way.  Set your position and angles, and look at it from all angles possible to make sure youre happy with placement, then let it cure at least 24 hours.  Then fill one side with epoxy, level, contour and texture it, then let it cure.  Lastly repeat on the other side.  The biggest problem I've found doing large gap repairs is in a single go, is that as you set it from one angle, then adjust a tiny bit, your left with a gap on the other side, and back and forth worsening as you move the parts.  Then, as you try to texture both sides, its REALLY easy to put a finger print or mark on the side you did first.  So keep going slow and youll have good results.

[Opabinia Blues]

1 hour ago, hadrosauridae said:

Looking good so far!  I would wait until you  have it soda blasted clean before adding the epoxy.  It doesnt have to match perfectly, just be somewhere close.  Once its fully cleaned and consolidated with Butvar or Paraloid, start with filling all the cracks first, then let that cure before repairing the gap.  I recommend doing that in 3 stages.  First is to make a center core of epoxy, it shouldnt fill all the way.  Set your position and angles, and look at it from all angles possible to make sure youre happy with placement, then let it cure at least 24 hours.  Then fill one side with epoxy, level, contour and texture it, then let it cure.  Lastly repeat on the other side.  The biggest problem I've found doing large gap repairs is in a single go, is that as you set it from one angle, then adjust a tiny bit, your left with a gap on the other side, and back and forth worsening as you move the parts.  Then, as you try to texture both sides, its REALLY easy to put a finger print or mark on the side you did first.  So keep going slow and youll have good results.

 

What tools/techniques would you recommend for texturing bone?

[Alex S.]

I couldn't agree more with @hadrosauridae on all parts.  As for tools you can often find clay modeling tools on Amazon or around and those are great. I've found regular dental tools to not only be helpful for prep but also for adding texture lines. Also if you haven't decided and have the funds the master mobile pro last with the immediate off would be great I couldn't justify it but I'd love to have it.

[hadrosauridae]

22 hours ago, Opabinia Blues said:

 

What tools/techniques would you recommend for texturing bone?

 

Texturing is where the artform of prep work comes in, and sadly its also my weakest area.  At the least, you want to make it not look like a wad of clay stuffed in there.  You can use dry sponges give the surface a lite texture.  If the bone has directional lines, they usually flow with the shape of the bone, and you can use a stiff toothbrush to lightly drag with those lines.  For contours, I find that a plastic card ( I always have a couple hotel keycards laying around) make good tools.  They are hard enough cut the epoxy, larger than trying to do it with a small blade, and also can be flexed slightly. 

 

Just spend some time looking at the piece you are about to remodel.  How would the missing bone surface have sloped, curved, bulged, etc.  Then think about how you can carve away a lump of epoxy clay to  match that.   At least with the paleosculp (as its the one I have experience with), it cuts best with a sawing motion on your tool.  If you try to just push through you will probably cause the epoxy to pull, stretch, or bunch up and not leaving a complete surface behind.  After I get the shape I want, I take a wet finger to work back and forth across the surface to smooth it before texturing.  Also, be sure to use a wet cloth to clean away any epoxy that is smeared on the edges of bone.  

 

The best practice spots are where you fill crack and small holes.