cels: better stuck or unstuck to douga?

[Spidercan]

Thoughts? I read somewhere that cels are more valuable unstuck. Then elsewhere that they're less likely to degrade if stuck. Specifically talking about mononoke cels

[zerospace]

The reason a cel is considered more valuable unstuck is because a cel stuck to a sketch is basically damaged. You don't pay normal retail price for a damaged item of any kind, do you? So, when you're talking about collectibles, it makes more sense that an undamaged cel is worth more than a damaged one . Also, sketches that are stuck to cels themselves are basically already damaged -- most cases of really bad sticking cannot be unstuck without damage to the sketch. It IS possible to unstick some sketches from cels without harming either one, but this takes some skill. Some people do pull them off and destroy the sketch in the process -- it just depends on the collector.

[GuyvarIII]

I’ve been told by professional conservators as well as other collectors that having cels stuck to anything is bad; because natural changes in air temperature and moisture cause materials to ever so slightly expand and contract. The expansion and contraction rates for the acetate plastic, the acrylic paint, and the paper are all different. Over time, the cel’s paint can adhere more to the backing paper/sketch, which, with temperature changes, can lead to the paint separating from the plastic acetate, causing cracking and chipping. Also, I’ve heard that leaving sketches stuck can lead to discoloration of the acetate, due to gases released from the paint building up between the paper and the cel. And that it promotes cel spotting if moisture builds up behind the cel.

In a general sense, for conservation purposes, paper is supposed to be kept out of the air to avoid yellowing, while plastics and paints need to breathe to release gases. So, storing cels and sketches together is also problematic.

Some say, as cels will adhere to whatever is put behind them, you should use some kind of acid free archival backing paper. Others use plastics, as it is harder for the paint to stick to a plastic surface. But, plastics warp over time, which, if the paint does adhere to the plastic, can lead to cracking and chipping. As neither of these two suggestions addresses the buildup of gases or moisture between stuck layers, still others choose to “float” their cels between mattes and filets, so nothing is behind the cel … but, naysayers say this will cause the weight of the paint on the cel's plastic acetate to warp and bend. And, while a cel's paint can be touched up, damage to its actual acetate plastic is forever.

[sensei]

I would not be as pessimistic as Guyver is, though it is certainly true that cels are to some extent "self-consuming artifacts," which carry the chemical seeds of their deterioration within them. Do a search for "vinegar syndrome," here or on the Web, to get a sense of what this can involve in worst-case scenarios.

But in my experience poor storage and exposure to light are much more damaging than a stuck sketch. If you store cels at a controlled temperature (about 70 degrees is ideal), without big fluctuations in humidity, they will stay in good shape for years. And while archival storage conditions can be demanding, most items can be stored safely inside polypro bags (slit down one side so fumes can vent) and slipped into a cel book that is stored upright like a book. And inspect your collection often: this helps you spot trouble as soon as it starts to happen, and also viewing the cels helps vent any fumes that might otherwise build up and damage the plastic.

My practice is to remove the sketch whenever feasible. But in cases where paint on the delicate edges (particularly tips of hair strands) is adhering to the sketch paper, it makes sense not to risk damaging the image. And there are professional conservators' services that will separate the two for you with much more care and less damage than you can.

[Spidercan]

I would not be as pessimistic as Guyver is, though it is certainly true that cels are to some extent "self-consuming artifacts," which carry the chemical seeds of their deterioration within them. Do a search for "vinegar syndrome," here or on the Web, to get a sense of what this can involve in worst-case scenarios.

But in my experience poor storage and exposure to light are much more damaging than a stuck sketch. If you store cels at a controlled temperature (about 70 degrees is ideal), without big fluctuations in humidity, they will stay in good shape for years. And while archival storage conditions can be demanding, most items can be stored safely inside polypro bags (slit down one side so fumes can vent) and slipped into a cel book that is stored upright like a book. And inspect your collection often: this helps you spot trouble as soon as it starts to happen, and also viewing the cels helps vent any fumes that might otherwise build up and damage the plastic.

My practice is to remove the sketch whenever feasible. But in cases where paint on the delicate edges (particularly tips of hair strands) is adhering to the sketch paper, it makes sense not to risk damaging the image. And there are professional conservators' services that will separate the two for you with much more care and less damage than you can.

Is there a way to find such conservator services? Thanks!

[GuyvarIII]

Is there a way to find such conservator services? Thanks!

You could always go with S/R Labs:
http://www.srlabs.com/

You can see a post with my experience in using them here:
viewtopic.php?f=61&t=25829

And, they have been used by other members of this board.

[Spidercan]

thanksz!