: I whole heartedly agree, but one of the downsides of working with
: conceptual artists is that they are very particular about what
: they want. In this case three stainless pedestals with
: transparent display boxes on the top. Nothing of the
: refrigeration system is to be visible, and the works should be
: able to be viewed from all sides, and above.

: The sculptures are
: 'life-casts', so a silicone mold of a head, filled with a
: mixture of blood and slightly saline water, frozen and then
: removed from the mold before being displayed in the freezers.

BLOOD ! ? Good grief! You got any hazmat signs on those displays? As a former artist, and a blood donor, I'm trying to get my head around this concept. It offends me, and intrigues me, on so many levels and in so many strange ways. Sounds like something Franz Kafka might write about.

Haven't these people heard of epoxy resin, oor acrylic casting resin? All they'd need is a thin shell of it. They could mix in all the blood and water they wanted. Frozen or thawed the thing would never leak.

Well, it is their art work.

: For added difficulty points, they need to maintain a frozen state
: for up to 6 months at a time, be able to handle a full melt-down
: without letting the blood mixture run all over the gallery
: floor, and do it all as quietly as possible in temperatures up
: to 25C.

Forget those specs. those are just average ambient air temperatures. You're never going to deal with JUST 25C temperatures if they have spotlights. The focused light is also focused infrared energy--heat-- which would only show up on a thermometer sitting in the beam of light. Inside the circle of illumination it is going to be a lot warmer than you want. I understand that there are infrared filters which can reflect a good portion of the heat produced by the flood lamps. The technology was used over a decade ago in high-end photographic slide projectors, so they could give a brighter image without melting the slide. As i recall, the filter worked somthing like a partially-silvered mirror, and was placed in front of the light source at a 45 degree angle to the light. the "mirror" was coated with a material which reflected Infra Red. Visible light passed through the mirror, but most of the heat (infra-red light) went off to the side and was removed from the projector by a cooling fan. Perhaps instead of changing your cases you can change the lighting fixtures and get cooler light. since i am imagining the lights being above these castings, and aimed at the tops of the heads, I think they may be your major source of melting.

: No wedding theme anywhere near unfortunately.. This work is about
: blood quantum - the dilution of indigenous blood, and how that
: affects cultural identity.

: I did consider a dessicant, but couldn't see how it would keep
: working once the moisture it had already absorbed froze.

You would need to change the dessicant from time to time. How you do that is an engineering problem I leave to you. I wouldn't want to spoil your fun. :)

: The big
: problem we had last time around was that the refrigeration plant
: wasn't keeping up with the waaay out of spec gallery conditions
: (26-27C 85% humidity with hot lighting) and the sculpture was
: getting slushy on the top, evaporating, and then there's no end
: of water vapor looking for somewhere to freeze.

Why am I not surprised at this. See what I said above about spotlights. The bloody/slightly saline mix is going to need to be considerably colder to stay frozen. As it starts to freeze, some of the salt in the blood plasma and saline mix will concentrate. The first parts to freeze will have a lower salt content, and the last parts to freeze will have a higher salt content. With the higher salt content, they'll thaw sooner, and thaw at even a low temperature. The native Americans who concentrated maple sap into maple syrup and maple sugar did it by freezing the sap, and collecting the unfrozen center where the sugars were more concentrated. Similar process used to make apple jack from fermented apple cider: Freeze the jug of cider, then draw out the unfrozen stuff in the center, which had a higher concentration of alcohol. Moral here: you need to get things colder.

: As soon as the
: channels close up, there's no air circulation, and the problem
: is compounded. The channels are 3mm wide slots around all four
: sides of the plate.

Make the slots wider, and heat them with a small heater (5 to 10 watts might do it) which is in contact with the stainless, underneath it, out of sight, and as close to the slot as possible. Many video tape decks (remember VHS tapes?) and high end stereo amplifiers used to have small heating elements in them to protect the circuitry from humidity. Check with an electronics repair specialist and see if he might get you some used ones from broken tape decks for a trial. As I recall, these things used to be called "Chill chasers, but that may just be our local nick-name for them.

: If we can keep the ice below -9C, then there
: will be no vapor, but that's proved a bit of an ask given the
: other constraints.

Have you considered using something like liquid nitrogen? There are medical oxygen packs which hold a liter or two of liquid oxygen, and release this through a regulator. A pack like this--or maybe a few to get the required volume-- could be modified by removing the coil through which the gas warms up before being breathed. you would get a metered supply of cold gas. Fill it with liqid nitrogen instead of liqid oxygen to avoid fire problems, and top off the tanks daily. Silent and no wires.

: Thanks for the suggestions - I'll keep them in mind if we have
: problems this time around. We made a number of changes to the
: systems prior to shipping them off to the next gallery, so
: hopefully the refrigeration plant can keep on top of things this
: time.

Good luck with this. Just curious. Where is this exhibit being shown?

PGJ