Thursday, April 17, 2008

Obisidan Knife

I've wanted to make a knife or spear point for a long time. Until a couple days ago I never made a point longer than a few inches. The first problem was to get a long enough piece of rock to work with. I started by knocking a long thin spall off a roundish nodule. From there I knocked piece after piece off making very few mistakes for once. I took a few pictures on the way to the finished product because I was afraid I would mess it up.

I switched to pressure flaking a little sooner than I should have. I could control the accuracy of the flakes I pushed off so much easier than when striking the rock. The problem is that the flakes I took off weren't as long and thick as when striking. I was too afraid to ruin the piece with a misplaced strike though so I picked up the ishi stick. The consequence was a thicker, duller blade than I hoped for. Near the tip it's probably a 2/1 or 3/1 width to thickness ratio. That makes it good for stabbing things but not so good for slicing. By the way, I don't plan to do either with this guy so don't worry. The finished point ended up being about 4 1/2 inches long.

After finishing the point, I selected an antler from my stash. I sawed of the tines at a nice wide spot. I put the antler in boiling water to soften up the inside of the antler. After taking it out it was pretty easy to scrape out the inside with some metal tools. I also filed down a groove in the sides since the rock was wider than the antler. When fitted together the blade fit about 1 1/4 inches into the antler handle. Ideally it would've been a little deeper into the handle, but I was satisfied with it.

After whipping up a batch of pitch as I discussed in my last post, I poured it into the antler handle. At the same time I heated up the blade over the Jesus candle so that the knife would have holy powers. I then jammed the blade into the handle.

As the pitch overflowed I molded it around all sides of the blade and handle. As the pitch cooled it became very easy to mold. Below is a close up of the finished product showing the black pitch.

The picture below shows you the overall size of the knife. The blade is now approximately 3 inches long. The blade feels very secure inside the handle.

Pitch - "Survival Epoxy"

Last November when doing trail work in the lower Sierra Nevada's I happened upon a tree that was gushing out sap. The picture below shows just a portion of the sap that was running. I took the opportunity to collect as much as I could. After finishing with this tree I found a few more trees that had pretty good quantities. I suspect the dry air in the region leads to more limbs cracking then most places.

I collected the sap to make pitch which can be used for many projects. Anytime you need to adhere one object to another, pitch can be used. I hadn't had a need for it until today when I hafted an obsidian blade into a deer antler handle. That will be the topic of my next post. To make pitch you mix equal parts sap and a hardening agent. Charcoal, white ash and powdered egg or mollusk shells are examples of hardening agents. I chose to use charcoal from the remains of my pottery fire.

First I rigged up a contraption to melt down the sap. The bottom of a beverage can rests on two wood blocks sitting over a candle. I put tape on the wood so the can wouldn't slip around. The small candle provided plenty of heat to soften up the sap.

Next I added a small amount of hard sap to the can.

After a few minutes it melted into a viscous liquid. I pulled out as much debris as I could to make it more pure. The more junk in there the more crumbly the final product will be.

Meanwhile I used a nice ergonomic grinding stone I found on another trip to powder up charcoal.

Then I mixed an equal amount of charcoal powder into the liquid sap.

Finally, after using it on my obsidian knife which I'll discuss in my next post, I took the remaining pitch and molded it on a stick for later use. All that needs to be done next time is to hold the pitch stick over a flame for a second to turn it to liquid.

Friday, April 04, 2008

Primitive Pottery and Cooking

Back in late November my crew mate Rosy and I gathered clay from a canyon on one of our day hikes. The clay had washed down through the middle of the canyon. Clay particles, being lighter than sand and dirt, settled on top then dried and cracked. When we gathered it we simply brushed off sand from the bottom of the piece. No purification was necessary.

After gathering the dry clay we put it in a bucket and broke it up into small pieces. We then added water to liquefy it. The clay sat in the bucket (with lid on) until about 2 1/2 weeks ago when we finally decided to use it.

Pure clay pieces gathered from the canyon.

The first thing we needed to do was figure out how much temper material to put into the clay. We used sand from the yard as temper material. Temper is added to the clay to prevent shrinkage when drying and thermal shock when exposed to fire. To figure this out I experimented with different percentages of temper using instructions from In the picture below, the five disks in the upper left corner each have a different percentage of temper from 0%-40%. After air drying them for several days it turned out that they all seemed good. None cracked (too little temper) or crumbled (too much temper).

It wasn't as easy making pots as I hoped. The toughest part for me was adding new coils of clay to a pot and getting it to adhere without squeezing so much that I made the pot too thin. All the creations pictured have 0% temper (which is best for holding water) except the one at bottom center. It was about 20% tempered. My hope was to make it into a cooking vessel. Inside it are beads and a three-legged (one leg fell off) turtle pendant I made. At bottom left is a combination plate/pot lid that I cracked by accident during the drying phase. At top center is a pipe that Kevin made. At top right is Rosy's teapot. The bottom right pot Rosy made using another bowl as a mold.

I meant to add some designs to my creations by pressing leaves on them but I missed that part of the drying phase overnight. I used a spoon to burnish them the best I could which aligned the clay particles making it shiny and better for holding water. After a day of drying some of the pots had small cracks in them. I used leftover clay to patch up mine. It is recommended to dry pots at least a couple days and preferably two weeks. Knowing that the climate is so dry here we probably could have gotten away with 2 days if we wanted. Instead we waited till we got back from our next hitch giving them about two weeks to dry.

From everything I heard and read about firing pots I had the impression that the chances of pots cracking or blowing off chunks during firing was really good so I fully expected to walk away with nothing but the experience. On the firing day there was pretty gusty wind which was bad since sudden changes of temperature (thermal shock) cause cracking and shattering. To counteract this, we set up a wind block as seen in the pictures.

To start we set the pots by the fire to warm them up. Over the course of an hour we gradually moved them closer and rotated them. The goal was to drive out the remaining atmospheric moisture. Heating too fast can cause moisture in the pot to boil which causes shattering.

After the pots were warmed up and dried, we raked the fire out into a ring and put the pots in the middle where the fire had been. For the next three hours we gradually moved the ring of fire in closer until it was totally on top of the pots.

Here you can see how the pots changed color during firing.

I dropped a piece of glass in the fire to test the temperature. Supposedly if you can melt glass then it is hot enough for clay. Unfortunately it melted on a few of the pots. Near the end of the four hours we added a lot of small wood to spike the heat up. Then we let the fire die naturally.

The following day we checked the pots. To our satisfaction none had shattered. All of them had some amount of cracking which isn't surprising given they cracked during the air drying phase. Despite a few hairline cracks, my little cup held water. My cooking vessel dripped water from the bottom, but I was able to cook up a couple eggs in it. It appears the eggs plugged up the cracks too because it now holds water. Overall it was a great success.

While we waited for the fire to die we took the opportunity to cook some meat on the coals. No need for a grill, oven or pan. The coals flake right off.

I also experimented with cooking ash cakes. I mixed flour, cornmeal, raisins and sunflower seeds together with water to make patties. I threw them onto the white ash and a few minutes later they were ready to eat. For more information about how to make them check out the ash cakes article at

The Body Hollow

Every since reading Practical Primitive's article about the body hollow shelter, I've wanted to build one. Sitting in the backyard one day not long ago I gazed upon the large pile of tree branches given to us by our neighbor. Then I glanced at the yard composed of sand. The words "build a shelter" popped into my head.

In the desert of the southwest there are few trees. Those that are around don't have leaves suitable to build a shelter like the debris hut. So one way to make a shelter is to dig and make it underground. The body hollow is basically half underground and half above ground.

For excellent instructions on how to build one, go to the link in the first paragraph. It has a great series of pictures. I won't try to recreate that here, but I'll tell you my experience.

I used a shovel to dig out the trench. My neighbor thought I was digging a grave until I explained what I was doing. Since the soil was pretty soft and I didn't have to dig very deep, this didn't take too long. The trench is the length of my body.

I filled the trench about half full with debris (leaves, needles and other detritus), then laid sticks across the trench. After that I started adding more debris on top. I made a little A-frame at the entrance to make it easier to crawl into.

I scrounged around every corner of the property to find debris. I even crossed the street to a vacant property and stole a binful of leaves. I laid sticks on top to keep them from blowing away. In front of the entrance is a ball of pine needles to plug up the doorway after crawling in.

The shelter should really have another foot of debris on top of it but I just didn't have the resources for that without opening a leaf raking business. If I could have I would also have filled the inside up so that I'd have to burrow in. I tried to sleep in it two nights. Both nights I made it through about 3 hours before bailing. The first night it was 47 degrees when I crawled out. Inside the shelter I was a little cold, but I could have toughed it out if I had to. It was definitely warmer than 47. At least the bedding was comfortable to sleep on.

Since I don't plan to gather more debris, I'm going to wait till the weather gets warmer before I try again. I think I could do mid-50s. If I were to do it again I'd probably try to lower the roof over my legs to make less air space for my body to have to heat up.