...to be more accurate, i think what i heard regarding a thick finish is that it is less 'flexible' and more likely to crack if the wood 'moves' because of temperature or humidity variations?
It seems to me CA is not flexible at all regardless of the thickness, but that's just my impression.
Well, that is not totally true, IMO, but I cannot give "empirial" evidence. Just as George stated about his pens, mine usually have a good thick coat. I have dropped pens numerous times and some are 4 to 5 years old with a good thick coating and no cracks yet. I do have a couple of small dents on my favorite pen, but no cracks. If the CA were not flexible as in a class like glass or some ceramics, they would have certainly shattered.
I can promise you that if CA were not "flexible at all regardless of thickness", then the shear huge number of people making CA finished pens on this forum for the past 7 years would have certainly reported it. If CA were not "flexible" in some very forgiving respects, it would not be in use today by the vast numbers of users. How else can it be explained millions(?) of CA finished pens made and only a few dozen or so with cracked finish, and most of those from assembly problems.
IN the case of flexibility - Where CA
IS flexible:
On oily woods, and in the case where the finished blank is CA'ed to the bushings, - in separating the bushings, the CA "lifts" from the blank. This is a common problem and can be searched on this forum. Just search for "lift" or "lifting". What happens is important to your idea. IF CA were not flexible, it would shatter or crack. But in these cases it "lifts" from the wood. I have pulled pieces of that were as thick as a fingernail and while "hard", it is more like acrylic or plexiglas or a finger nail than glass. And in my own experience, the thicker is less likely to crack than thin. The thicker the CA finish, the more it seems to be like a "shock absorber" as in lexan.
When CA is used on end cut and some other woods that are very prone to "movement", especially if the wood is green, then yes, it will crack as will poly or acrylic or lacquer. The only way to prevent wood movement when, especially when it is green is to stabilize it. Some woods move more than others. IN the case of cross grain or end grain pens, the problem is not the CA but the wood. Wood moves unless it is stabilized.
