Wednesday, November 4, 2009

Harpoon Foreshafts and Gelatin Seals

Between the leftover Halloween candy and visions of giant gummy seals I hardly slept at all last night. I've been thinking a lot more about the ballistic gel seal idea.

I think that in order to properly test both barbed and toggling harpoons the gel seal would have to have three layers. Skin, blubber, and meat. I think rawhide would work for the skin layer, and two layers of gel could serve as the blubber and meat layers. The meat layer would be a dense ballistic gel and the blubber layer would be a gel made with more water, so it would be a little squishier. If you aren't squeamish, you can see the layers that make up a seal here: culture camp how to butcher a seal demo.

I've been using Knox Gelatine (its spelled that way on the box) to make the ballistics gel. To make edible gelatin, the recipe is one packet of Knox's for 500 ml of water. I'm using about 700 ml of water and in the first batch I used 2 packets of Knox. This made jello. All it was missing was the sugar and the floating peas and chunks of ham. I remelted the gelatin by floating the tupperware in a sink full of hot water and mixed in a third pack of Knox. The 3 pack-700ml gelatin block is the one I used in these photos. It held together a little better although it still failed (the third picture in the triptych below). It might make an ok fat layer, but I think its still softer than any real animal fat. I'm melting it down again and I'll add a fourth pack. My guess now is that 4 packs of gelatin will make an alright fat layer and that I'll need at least 5 or 6 packs to the same volume of water to make a dense enough muscle layer.

One thing that this avenue of thinking has illustrated for me is the functional difference between the long foreshaft on the barbed harpoon and the short foreshaft on the toggling harpoon. They start to make sense if you think of a seal in three layers, with skin and fat near the surface and meat somewhere deep inside. The toggling harpoon head works in the fat near the skin while the barbed harpoon needs to grip the denser muscle tissue deep inside the animal. The different lengths of the foreshafts would deliver the harpoon heads to the appropriate depths inside the seal.

The harpoon reproductions on the left are two different cultures, and all of the tools made by the Palaeoeskimos were smaller than the Maritime Archaic equivelant, so its kind of like comparing apples and oranges. However, the Maritime Archaic Indians also made toggling harpoons, and the foreshafts for those are much shorter than the foreshafts on the barbed points. One recovered at Port au Choix with the Maritime Archaic toggling harpoon head still attached was only 18 cm long. Out of context, it could have passed for a large Palaeoeskimo foreshaft (the foreshaft in my Palaeoeskimo reproduction is 12 cm long). The Maritime Archaic made both barbed and toggling harpoon heads and they made both long and short foreshafts, which makes sense when you consider where each of these kinds of harpoon heads would work best inside the body of the marine mammals they were hunting.

Maybe an experiment built around foreshaft lengths would be a good excuse for stabbing blocks of ballistic gel with harpoons. I'm thinking about other tests involving barbed versus toggling harpoons and stone endblades versus self-bladed harpoon heads. Thank you everyone for commenting on the last post - keep the ideas coming.

Photo Credits:
First, Third, Fifth: Lori White
Second, Fourth: Tim Rast

Photo Captions:
First, Stabbing a gelatin block with a barbed harpoon head
Second, Knox' gelatin and the container of gel
Third, Stabbing rawhide and gel with a Dorset harpoon. The glass is there to give the harpoon head room to toggle, but it didn't happen.
Fourth, Maritime Archaic barbed harpoon, top, and Dorset Palaeoeskimo toggling harpoon, below
Fifth, still stabbing gelatin


  1. Sounds like the sort of experiment that needs writing up and publishing somewhere.

  2. "Stabbing rawhide and gel with a Dorset harpoon. The glass is there to give the harpoon head room to toggle, but it didn't happen".

    I always thought the toggling would have occurred after you stuck the animal and only once you pulled on the line? I susect you'll need a seal-sized body to stab and yank on to see any toggling.

    In any event, I really like your reasoning about foreshaft lengths. This is something i've never considered from looking at these items from a strictly archaeological context.

  3. Yeah, the toggling should happen in the fat layer, but so far I've been working on the consistency of the gel, so I haven't made a thick enough block for everything to happen inside the gel. The gel block wasn't thick enough for the harpoon head to pass all the way through and for the barbs to catch and detach the harpoon head from the foreshaft, so I needed a void space on the other side.

    Right now I'm thinking of using clear 2 litre pop bottles with the ends cut off. The bottom half would be filled with dense "meat" gelatin and on top of that there would be the looser "fat" gelatin layer. The whole thing would be capped with rawhide skin. The fat layer needs to be able to smoosh around a bit and the clear plastic bottle would allow that and still let us see whats going on inside.

    For the meat layer, I'm thinking of suspending a latice of sinew strands so that the barbs have something to catch on when the line is pulled. I'm finding the ballistic gel to be good for creating resistance on the trip in, but its not gristly enough to catch the barbs on the way out. I could just use a porkchop or something, but I'd really like the medium to be translucent so we can see how the parts are working inside.

  4. What about using some tulle or some other mesh fabric , swirled around in the gel? You could even do a layer of gel, a couple of layers of fabric, another of gel, more fabric, etc. Just to add some "grip" to the gel.

  5. That's a good idea, Vicky. If the sinew didn't work I was thinking about using those plastic mesh bags that fruit comes in, but tulle is a better idea.

    I have to admit that there's kind of a Frankenstein's monster appeal to me in creating the model entirely out of rendered animal parts. However, the tulle could play with the jello salad angle in a Tim Burton kind of way. I like the idea of creating a ballistic dummy using only items you can find at a bridal shower.

  6. Another thought is chunks of sponge, although they're not often found at a bridal shower. At least, not at any I've ever attended.....


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