I have noticed this too, over the years.  But, I believe Pierco has
remodeled their frame, and perhaps the problem has been fixed.  It can't
be the plastic, but a violation of the bee space dimension.  Jack Kuehn,
University of Illinois Bee lab
 
On Sun, 12 Jan 1997, James C. King wrote:
 
> >
> >Date:    Wed, 8 Jan 1997 22:49:05 -0600
> >From:    Garrett Dodds <[log in to unmask]>
> >Subject: Pierco Plastic Frames and Foundation
> >
> >Hi,
> >
> >I was wondering if anyone has used the Pierco Plastic Frames and
> >Foundation?  What are their pros and cons?  How are they compared to wooden
> >frames?
> >
>
> I think that one pro of using Pierco is the labor reduction vs wood frame
> assembly, wiring and foundation insertion. Another is the fact that the
> bees use these frame well - I often see brood in Pierco frames side to side
> and top to bottom.   Con is cost and the fact that bees build burr comb on
> top of the plastic frames.  I have some Pierco frames mixed in my outfit
> and anytime I am attempting to separate two brood chambers and I find them
> badly stuck together, it is because there are one or more Pierco frames in
> the bottom brood chamber that the bees have connected to the bottom frames
> of the upper chamber with burr comb.  This is enough of a problem for me
> that I don't plan to purchase more.  BTW, this burr comb thing is not
> related to the wrong size space between the brood chambers.  Side by side,
> with wood no burr comb, but with plastic, always burr comb.
>
> Jim King, Rieglesville, PA
>