A question for those of you in the frozen/freezing/thawing north..

I've been building a set of display freezers - double glazed acrylic box with stainless plates for Ice sculpture exhibition. They're 400mm cubes, with a small fan circulating air. The stainless plate is 3mm thick with the refrigeration evaporator tubing soldered to the underside.

The problem I'm having is that the 'moist' air is pulled down around the edges of the stainless plate, and recirculated up the inside of the inner perspex box - as it is pulled down around the edges of the plate, the moisture turns to ice crystals and gradually blocks the ventilation channel. That in turn causes the sculpture to gradually melt from the top down and refreeze as a small mound of 'frost' in the bottom of the unit.

I've been working on a defrost system, but we don't have a lot of 'spare' refrigeration capacity, and the defrost I have at the moment takes longer than I'd like to clear the channel.

So, the question: Is there something I can treat the edge of the stainless plate with to prevent ice forming there? We're talking about -15C with air moving over it.

We spend 99.9% of the year well above freezing here, so this is foreign territory for me - for those of you who spend half the year building kayaks because the outside world is white and solid it's probably an easy question!

Thanks for your thoughts,
Simeon.