How flexible should a shell chair be?  

wegner's 3 legged?
No flex at all.

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Eames chair? There must be a crack, even a small one can make sitting on a chair like feel a bit alarming, I had one of the baydur Casala chairs that did that...when you sit down and lean back look closely at the area near your hips. It can be repaired but I'm not sure if it would ever be as strong.

repair...
if properly repaired it can just as strong or stronger than before....find a boat shop to see about proper fiberglass repair...

Do you mean the new polypropylene plastic ones?
I noticed that the newer production ones are more flexible than before. I have one that I bought about 6 years ago and it is noticeably more rigid.
I don't like the more flexible shell... yet another reason to hate on Vitra.

thanks everyone! They are...
thanks everyone! They are vintage and yes, I was referring to Eames shell chairs.
One of my chairs does have a crack in the top and a I do have a few that are more flexy than others. I live in northwest washington with the San Juan islands about two blocks from my house, so there are plenty of boat shops around 🙂
And just a few more questions...
What exactly goes into have them professionaly repaired? Should I bother with sanding and Penetrol? I've heard that Penetrol will yellow white chairs, any other suggestions? Also any tips on brightening up discolored white chairs?
Thanks everyone!

White shells
I used a Oxi Clean gel on my white shell and it really came out nice.
(edited by DA - no advertising on the forum please)

Tyler...
I just came across your site earlier today! Your chairs turned out beautiful, total furniture porn! I don't recall if you said you tried it on the colored ones, I have several dirty chairs and just want to be sure it wouldn't bleach the others!