Weird. Did you ever find any explanation to it? It seems like there are
several people experiencing these effects:

http://mail.mems-exchange.org/pipermail/mems-talk/2008-May/241810.html

http://mail.mems-exchange.org/pipermail/mems-talk/2004-July/013563.html

http://mail.mems-exchange.org/durusmail/mems-talk/22713/

Any thoughts?

/Mikael

> -----Original Message-----
> From: mems-talk-bounces@memsnet.org [mailto:mems-talk-
> bounces@memsnet.org] On Behalf Of Lupin
> Sent: Tuesday, July 14, 2009 1:47 PM
> To: General MEMS discussion
> Subject: Re: [mems-talk] PDMS curing problems when using plastic
> masters
>
> I had same problems when mold PDMS on another cured PDMS. It cured
> everywhere except where it was in contact with the bottom PDMS.
>
> On Mon, Jul 13, 2009 at 11:19 PM, Mikael Evander
> wrote:
> > Hi.
> >
> > I've just run into a strange problem. I've previously used several
> different materials as master for PDMS molding and never ever had any
> problems. The other day I tried using a laser ablated polyester film as
> a master and the PDMS cured everywhere except where it was in contact
> with the polyester. Others in the lab seem to have seen the same
> problem when using acrylic masters.
> >
> > I haven't been able to find anything about it and e-mailed dow
> corning without a response. Has anyone else seen this and know why it
> happens? Evaporating solvents? Materials that aren't compatible with
> PDMS for some reason?
> >
> > thanks in advance!
> >
> > /Mikael