Don't know how small indicators you need, Bev. Came to think of old sort of mechanical thing I saw many years ago. Was based on stuff that changed length or volume when wetted. Kind of simple mechanism tripped and red sign appeared. Same idea as those 'heat buttons' inserted in the body when you buy chickens. When the meat is heated to certain depth and time, the tiny thing triggers and 'plepp', you know the chicken is ready. Costs nothing in volumes.
These days with micromechanic tech should make this a piece of a cake. So if chemistry does not fulfill your requirements, try micromech.
Ingemar
-----Original Message-----
From: Ken Mc Gowan [mailto:[log in to unmask]]
Sent: den 28 maj 2001 23:02
To: [log in to unmask]
Subject: Re: [TN] Permanent Moisture Sensitivity Indicators?
Just my $ 0.02. Why not design strip with 'one way' absorbtion barrier. Use
anhydrous copper sulphate which will go blue on contact with moisture/water.
I will not conduct my thing about the origin if colours in transition metals
but it would happen.
Regards,
Ken Mc Gowan
----- Original Message -----
From: "Bev Christian" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, May 28, 2001 12:29 PM
Subject: Re: [TN] Permanent Moisture Sensitivity Indicators?
> Seriously guys, what I am looking for is a PERMANENT change. I have been
> given a few good leads and after I have checked them out I will share the
> results with TechNetters.
>
> regards,
> Bev
> Research in Motion
>
> -----Original Message-----
> From: Ingemar Hernefjord (EMW)
> [mailto:[log in to unmask]]
> Sent: May 28, 2001 9:11 AM
> To: [log in to unmask]
> Subject: Re: [TN] Permanent Moisture Sensitivity Indicators?
>
>
> Brian
>
> then I propose 'chinese women's hair'. Same mechanism as in a hygrometer,
> but let the shaft through a hole in the unit, put an index or pointer on
the
> shaft, and..behold...you can stay on the ground and check the humidity on
> inside of the units that are 200 meters up in the masts. Yes, the pointer
> must be very big, or you have good binoculars. Don't tell me you see
> problems with the women too.
>
> Ingemar
>
> -----Original Message-----
> From: Brian Ellis [mailto:[log in to unmask]]
> Sent: den 28 maj 2001 11:58
> To: TechNet E-Mail Forum.; Ingemar Hernefjord (EMW)
> Subject: Re: [TN] Permanent Moisture Sensitivity Indicators?
>
>
> Ingemar
>
> Silica gel is a modified, expanded, form of silica and is inert. Colour
> indicated silica gel is not inert: it is laced with a beautifully ionic
> salt which is not going to improve a PC Assembly. It is cobalt chloride
> which is blue in its anhydrous form and turns progressively redder in
> its dihydrate and hexahydrate forms. All forms are water-soluble and
> hygroscopic. I'd be **extremely** cautious about placing anything like
> that close to an assembly or any component thereof.
>
> Brian
>
> "Ingemar Hernefjord (EMW)" wrote:
> >
> > Just indicate and not quantify? Why not use the kind of crystals that
are
> put into all delicate transports, changes to nice azur blue if it has been
> exposed to wet. At least we use them as simple indicators, costs nothing,
> you can put in one single crystal or several pounds. Reversible too. Don't
> know the chemical composition, used everywhere on this planet. Modified
> Silica maybe.Donno.
> > Ingemar
> >
> > -----Original Message-----
> > From: Bev Christian [mailto:[log in to unmask]]
> > Sent: den 24 maj 2001 00:29
> > To: [log in to unmask]
> > Subject: [TN] Permanent Moisture Sensitivity Indicators?
> >
> > TechNetters,
> > Hann asked this same sort of question May 9th and I am not aware of any
> > answers being posted. Certainly not with the same title (searched
> > archives).
> >
> > Ever have clients dunk your hard work in water and then claim that you
> > couldn't make good product? Do any of you know of any really small,
> > moisture indicator strips that permanently changed color when they are
> > dunked in liquid water, as opposed to just being exposed to high
humidity
> > for long periods of time? I know, I know a tall order. Any help would
be
> > appreciated. Thanks.
> >
> > Bev Christian
> > Research in Motion
> >
> >
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