Kathy, thanks very much for these comprehensive and useful notes. As always, you're a font of knowledge. I'll pass your comments along to my colleague.
Original Message:
Sent: 08-07-2023 14:18
From: Kathy Hall
Subject: Microabrasives units
Julie,
Starting with a disclaimer: I am assuming your contact is an experienced metal conservator with knowledge of corrosion stratigraphy and who would of course check for mineral preserved organics and other evidence before beginning treatment.
I obsessed about the perfect airbrasive unit for a while. I wanted a unit like the S.S.White ones I'd used in the UK, which I remembered had tiny nozzles enabling very fine control, and with parts which were easy to replace if necessary. These units were not available in Europe. I considered carrying over the essential parts in a suitcase and having a glove box built locally. But based on cost, I gave up and instead bought a Renfert dental sandblaster second-hand from a jeweller's supply company. (We got the one with two tanks but the single tank one would be fine, we never use the second tank).
For extraction we first used a shop vac, but this was very noisy and the year after we replaced it with a DUSTVAC from INSITU Conservation which is much quieter (but not cheap). The Renfert unit has a small water trap to stop the medium (usually 150 micrometer glass beads) clogging and we also bleed the compressor every time before starting.
BUT. This system does not have fine control. The nozzle does not provide a controlled fine jet, but rather a cone shaped spray. We use it mainly for the initial cleaning of sediment and porous outer corrosion layers from iron artifacts. It's also a dream tool for removing sediment from the uneven surface of copper oxhide ingots.
To be honest it's not my primary tool for cleaning archaeological metals. Assuming your colleague is in Turkey and has similar cultural material to us, I'd recommend first spending money on a good micromotor (the Schick ones are great, used together with tiny round carbide steel burrs; we have the Q basic) and an ultrasonic dental scaler such as the EMS mini-Piezon. These might be more useful investments. Both tools can be easily used under the microscope, and the EMS is great at removing calcareous accretions, too.
Hope this is a bit helpful,
Kathy
------------------------------
Kathy Hall
Senior Conservator
INSTAP Study Center for East Crete
Crete
Original Message:
Sent: 08-07-2023 11:39
From: Julie Unruh
Subject: Microabrasives units
Hi Kathy!
As I understand, it's both iron and copper alloy. Thanks for any advice.
Julie
Original Message:
Sent: 8/7/2023 12:40:00 AM
From: Kathy Hall
Subject: RE: Microabrasives units
Hi Julie!
I have struggled with this and can share notes, but am wondering first which material is the main issue; iron or copper alloy?
Kathy
------------------------------
Kathy Hall
Senior Conservator
INSTAP Study Center for East Crete
Crete
Original Message:
Sent: 08-03-2023 17:15
From: Julie Unruh
Subject: Microabrasives units
This is posted on behalf of a colleague who is not on this list. With full understanding of the need to be cautious with microabrasives, a colleague is looking for a microabrasive unit for use with archaeological material. The unit would be used to reduce metals corrosion, and possibly calcium carbonate accretions. Does anyone have recommendations for particular models, especially those available in Europe? Could anyone advise regarding appropriate abrasives and nozzle sizes for safe and detailed work without clogging? Thanks for any observations.
------------------------------
Julie Unruh
Austin TX
------------------------------