Questions for knappers

I was working a couple flakes last night into points per the request of the historian lady whose house I'm roofing. She had sold most of her artifacts years ago when she became disabled as an extra cash reservoir and now she only has a few shadow boxes on display with 25 or so points in each. She said that she doesn't know anyone besides me who is interested in primitive tech so she wanted me to knap a point from local rock for display and as a family heirloom to pass to her great grandkids. Since she directed me to some local rocks near her house, I decided I would make the points from some of that source rock. (they had been removed from fields so I wasn't worried about historic significance even though a Muscogugli tribe lived where her farm is.)

local rock is a long way from ideal for knapping. It is usually poor quality chert, often with freeze fractures, and always with ancient crustaceans interrupting the flake bells. Often I wind up with layered "chunks" toward the middle of the piece that are extremely hard to remove. It will usually make the flake one-sided as far as weight is concerned.

I have a few questions for the advanced knappers who have hopefully worked with such low quality stone before.
1. How do you prevent these 'sudden-stop' cliffs from forming initially?
2. When they do form anyway, from being interrupted by impurities or vacancies in the stone, what is the best way to remove them?
3. If I have a coarser stone that would be good for grinding, like a river cobble, would it be possible to grind down the humps? (not lovely-lady humps). I've tried this before with marginal success, I've broken one or two like this so I didn't try it last night.
4. Would indirect percussion be more appropriate than pressure flaking this rock?

Thanks in advance!
ycc

Have you tried "baking" the stone? My Dad is a knapper - I could only call myself an apprentice. Our local chert is not so good either. He took some stones in unbroken form - rounded from erosion, about the size of a grapefruit or canteloupe - and "baked" them in a very hot campfire. This changed the consistency of the stone just enough to make it more workable. He just built a good sized campfire and put the rocks in and let it burn out.

I can't say why it worked. Perhaps it was like tempering metal. But it did work.

Just make sure that the stones are completely dried out before you put them in the fire. If they have any latent moisture at all, they will EXPLODE. Also, if they already have cracks or tiny fractures, they will most likely split or break.

Good luck to you! Knapping is harder than anyone would guess, especially with brittle stone.

PTW, you are correct, this was used as a way to "heat treat" cert to make it easier to work.
The archaeological society I belong to did this as a demonstration this last summer.

The guy that did it had to do it at home with coals and sand, they wouldn't let him do it in front of spectors for fear of the rock exploding (Demo site rules)

I will give that a try, thanks.

Post a pic of your rocks. I've made arrowheads out of alot of uncooked rock. They don't flake as smoothly and are rough to the touch but they work.

I tried to knap a mess of Flint river flint years ago that my bud found in the river. But there were way to many fractures in the rock. I figured that the rock had been over cooked by mother nature. I did get a few workable pieces and made a few good arrowheads. Made alot of flintlock flints.

If you are going to cook your rock, put the rock in a fire pit at the bottom, build the fire around the rock, keep it burning for a good amount of time then just walk away. Let the fire burn out, then cool naturally. Go back in a few days and dig out your rock and it will have made the change.

I'll snap a few pics as I work some soon. I made two last night for the little old lady and now she has them on a plaque (she made it as I worked today) like its some fancy art.. I told her they were very crude and I'm no artist, but she was just amazed that someone in this day and age was more interested in rocks than bullets.

I did take pics of the ones I worked on last night I'll get them up in a little while. Thanks guys, for all the advice.. I'll stay clear away while they cook!

here are the points I did last night. Hopefully you can see the "chunks" I'm talking about.

http://i248.photobucket.com/albums/g...s/DSCN2200.jpg

http://i248.photobucket.com/albums/g...s/DSCN2196.jpg

and just for kicks..
http://i248.photobucket.com/albums/g...s/DSCN2193.jpg
clockwise from top left, 2 pieces of coral I traded leather for, local chert (pinkish), more coral, and the chunk on the bottom left is what became the larger head in the pics with the quarter. I never took pics of the coral pieces when I made them so I figured it was time ;)

thanks crash for this most excellent camera!

Very cool, good work.
Used to have a couple of guys in the shop back in my factory days, thet were pretty good, looks to me like your well on your way.
Glad your, pic's are back, worth 1000 words.

Good looking arrowheads. I also like your tools.

I'm starting to get the fever now.

thanks guys. I'll try to get some pics of the spalls tomorrow to put up so you can hopefully see the chert I'm working with lol.

I prefer these horns and stones to the brass tipped thingies. seem to grip better and the bone end doubles for a light hammer for roughing. I'm working on the handle for the antler-hammer you showed me a couple months ago.

FVR you must've gotten the flint from above the fall line. the nearest that is documented flint in the Flint River is above Albany, and it's protected.. no harvesting it. It is really rare down here to find suitable stone.. gotta try this cooking thing soon.
Do you think the heater out in the chop shop will be hot enough or do I need a BIG fire.. outside, bonfire size?

for the record, I tried to give you both rep, but the system says NO!
Thanks for the help guys!!

Looking at the "chunks," is it possible that you are pulling up or pushing down a little too much when you are pressure flaking?

If you can't get the antler points to work for pressure flakers, you might try a copper point mounted in a handle. The copper is soft enough to absorb a little of the pressure, which might make your flaking a little more controllable. The stone will also "bite" into the copper a little so it is easier to set the flaker on the edge.

The flint that was given to me was ages old sitting in a basement.

Google heat treating flint and see what you come up with. From what I've heard and read, it needs to be a long hot heat with a long cooling down period. With no moisture as this will cause the rocks to explode.

Heat treating actually changes the make up of the rock.

I generally push toward the center of the rock if you imagine the centerline plane, using my arms, shoulders, and knees (rock and hands between knees). I push with all my might before shifting slightly off-center. I watched my ?mentor? do it this way and it is the way he explained it to me.
I have tried the brass/copper tipped handles with the same results on local rock. The coral flakes really well, and I used horn on it. I didn't like the feel of the brass on the coral and wound up with gaps.. I'm really still quite new to knapping so I may give it another try. I'll have to get the stuff to make one since I was using his tool. And maybe I just need more practice to keep from forming the legdes in the first place LOL!
Maybe I'll get off work in time to go by the hardware store tomorrow. No hides in process so this is something I will be toying with over the weekend, during the rain.. I'll keep you posted on the results.
Thanks for the tips guys. I'll be cooking rocks this weekend rather than cooking on rocks, so hopefully I won't lose an eye to shrapnel. (It's all fun and games till..)

Well, remember this ----- there ain't a darn thing wrong with the points you showed us!

Heres some of the rocks I'm working with. clearly I try to avoid obviously pitted areas and try to spall flakes with the work ahead in mind. maybe you can see the textures well enough.
some really hard stuff
http://i248.photobucket.com/albums/g...s/DSCN2210.jpg
http://i248.photobucket.com/albums/g...s/DSCN2209.jpg

http://i248.photobucket.com/albums/g...s/DSCN2208.jpg

some slick stuff with lots of impurities
http://i248.photobucket.com/albums/g...s/DSCN2207.jpg

http://i248.photobucket.com/albums/g...s/DSCN2205.jpg
http://i248.photobucket.com/albums/g...s/DSCN2206.jpg

some of the boulder I just brought home.. really brittle with many little fractures.. might not be much good, but I spalled out a couple tools. you can see the bottom one is a preform for a spearhead. close-up of the texture of that piece is last. I don't think it's gonna be any good for knapping, but we'll see. Not sure cooking would even help this one.
http://i248.photobucket.com/albums/g...s/DSCN2202.jpg
http://i248.photobucket.com/albums/g...s/DSCN2203.jpg
http://i248.photobucket.com/albums/g...s/DSCN2204.jpg

I threw a small flake into the heater out in the shop last night. kept the fire going for several hours, threw a couple more logs in and went to bed. when the fire went out a little while ago, I checked for the small rock and only found a couple fragments lol.. I gotta do better than that. Still reading on a couple sites about heat treating.

Save those pieces, and see if they will spark on a file, or knife......natural fire steel kit.

Sounds like they shrunk in the dryer.

Looking forward to see what you make.

I'll go try them now :D

they didn't spark on old knife steel, nor on a piece of rediron

I would have guessed that they would, just looking at the pictures.
They have the clear/creamy look to them.
Could be that they softened up after heat treating, do you have a piece that hasn't been heated?

These aren't a commercial "fire starter" so you need a sharp edge on the piece of stone.
It's harder than a store bought one.

Try it with a old file or hack saw blade, some knives won't spark.
The sparks are just hot fillings that you just knocked off the steel with the rock.