This is a link to a short video of Karl Lee pressure flaking glass . It is of interest to me because it illustrates how he uses his knee “like a vice” to remove the flake. The large piece of glass was modern, and probably a table top. This is the end result.
Today has been miserable in Manchester, an ideal day for being sat behind a desk, sorting out all those jobs that need doing. I found myself in the backyard, in the rain. I have been inspired since my visit to the museum earlier in the week, and think I am getting it. Consequently, I took three points made previously and reworked them, or refined them to bring them more in line with the museum examples.
I know you shouldn’t have favourites, but it’s the middle one. Then the one on the right and then the one on the far left. I actually learned the most from working on the one on the far left, and then was able to apply that learning to the other two. Essentially my edge control is getting good. This is allowing me to get flatter points, and in turn serrate the margins more subtly.
This is one of the museum examples with a broken tip, angled to show the degree of retouch. You can see how the flaking really penetrates up to half way in creating a ridge or spine.
This is my version. Shape and size and margins are all good. The needle like tip is needle like, the area to improve is fully invasive retouch. It needs to penetrate further in. I therefore need to take a leaf out of Nick Overton’s book and sort that out on my first pass, then bingo!
This morning I paid another visit to the Manchester Museum and Gareth Frier was kind enough to dig out their Kimberley Points collection for me. My aim was to compare and contrast two of my own points with the museum originals. The two points in question are produced from the same piece of period glass bottle (see here and here) and are headed for Eleanor Casella’s teaching collection. Long story short: one of my points is a good replication, the other less so.
The above right is the ‘less so’. The point on the left is the original and as can be seen, it is much more refined in its retouch. They are keeping their retoucher much sharper, as it states in the texts, and it is interesting to see what that actually means in practice. Consequently, the original sits flatter on the paper in spite of its twisted longitudinal profile, and I now think that it is this flatness that allows more detailed edge serrations. I went in thinking it was edge angle that would be different, but it is flatness, which leads to a reduced edge angle and ultimately thinner margins that can be serrated. I have left my version with Eleanor as I said I would drop it off today, but I would like to continue flaking in order to flatten it, if she wants me to.
I am pleased with this second one. To all intents and purposes it fits the Kimberley Point criteria. The point on the left is the original and it has been made from a thick (at least 7mm) piece of glass and completely flaked on both surfaces. Mine on the other hand is made from the side panel of a glass bottle and has some original ventral surface left. This is true for almost all the other pieces, though usually to a lesser degree. I have also left some original dorsal surface to keep the lettering because I like it, and other examples discussed had this. I am pleased to say that this piece would be at home in the box with all the other originals.
I was more cautious with this one and it turned out longer. I tried to stick to my method, ventral first, then dorsal, then the point, however the angle of the edge face made me improvise a bit. I am pleased with the needle like point, and am going to arrange to go back into the Manchester Museum to compare and contrast. I think the key difference between mine and the actual points may be thickness and edge angle. Let’s see.
The next post will be about home made pressure flaking tools, as we have been innovating in our twice weekly knapping get-togethers.
This is one half of a piece of period bottle glass recovered from Chorlton Ees. My aim this time was to make a larger point and maintain some of the lettering on the dorsal surface (see Foraging for early 20th Century glass and ceramics). I used a glass cutter to score the inner concave ventral surface of the larger piece of glass, and then tapped the dorsal convex surace with a hard hammer. The large piece split cleanly into two useful preforms, one of which you see here. I then started to work on the ventral surface of the margins to produce a steep edge angle. This would allow me to flip it over and start using the newly created steep edge as a platform for penetrative flakes. The aim of this penetrative flaking was to flatten the convex curvature on the ventral face. I was able to straigten and steepen the margins but was not as systematic as I could have been. Working around a thick area semi-disaster struck!
I called it a day in the lab and took both pieces home, and the following day finished it off. The ‘A’ is a useful landmark on all three photos and gives an insight into the degree of reduction. I am getting a feel for this thicker and uneven material and was able to avoid a large internal bubble, which is why the base has remained relatively unworked. The end result isapproximately 76x26x7mm and pretty well flattened on the ventral side.
After the above photograph was taken I serrated the margins. My main learning from this piece is to be systematic in my reduction sequence. If my edge steepening had been more consistent I would have achieved a longer point. I am making some points for Eleanor Casella’s teaching collection and I think this can be one of them as it has an interesting provenance and biography, as well as being an aestheically pleasing example.
We have been having regular Tuesday and Thursday evening ‘knapp-ins’ for the past few weeks. Between the three of us we each gravitated towards different materials. Nick focused upon the remainder of the thick microwave turntable. Rob brought in some Langdale Tuff, a volcanic material with a fantastic texture, and I brought in a bone china plate. This bone china is hard, and very difficult to get long removals from. It really does seem to be a case of heavy abrasion to get incrementally longer removals, only to abraid again to get a bit further. Each of the above removals was hard earned.
Both Koalaboi and Nick recommended having a look at Paleomanjim’s Youtube channel. He uses a number of methods depending upon source material, but to maximise flake length he combined two approaches. Firstly he used abrasion and removals to create a steep angle that can be used optimally for one face only. He also used a pad with a channel cut into it. He has identified that having this void below the flake being removed means that it has absolutely no support, and thus comes off cleanly. Even small amounts of support (contact) can lead to step fracturing. This makes sense, although it doesn’t seem to be reflected in the Kimberley Points literature. Once optimal length flakes have been removed from one face, the the margin in prepared so as to remove optimum flakes from the second face. This process is primarily aimed at thinning and creating a lens like cross section. I have a couple of fragments of this material left, and so I am going to test out this steep platform method this Tuesday evening.
On Thursday evening I had a knapping session with Nick Overton and Rob Howarth. The ‘dish of the day’ was a toughened glass microwave turntable found in Nick’s garden. It took me a couple of hours to be able to get beyond the raised edge that was the outer lip of the turntable. As such it has been a masterclass in working angles and really got me thinking. Following the published methods is very interesting and the previous post focused upon managing the curve on bottle glass. However, this toughened and lipped turntable presented a different set of problems. It has made me think about the difference between aboriginal examples with plano-convex, and those with lens like cross sections. I wonder if plate glass examples like this lead to lens like cross sections because both faces are worked in a similar manner? I finished the above preform off this morning.
As can be seen, it has reduced in size considerably, and this is a reflection of working to get increasingly shallow angles and therefore longer removals.
This image shows better the degree of removals from the surface, and I can now report that the really long removals are in fact a combination of well prepared platforms that allow pressure to travel along a shallow surface angle. These shallow angles come from transforming a perpendicular edge into a steep angle, and then using this steep angle as a platform to take another removal that creates a longer shallow angle one. None of this discussion is new, however I am beginning to be able to apply these aspects systematically within a meta-approach to either plate glass or bottle glass. I am making practical sense of the textual descriptions that do not really separate out how these processes change (or remain the same) depending upon the materials used. It would be useful now to revisit the Manchester Museum examples to see if I can recognise if the source material was either plate or bottle glass, and if this actually does reflect a plano-convex or lens like cross section. Anyway, to para-phrase Nick, it has been immensely satisfying transforming this microwave turntable into something far less useful!