especially for the cheap UV curable type.... the problem  is the UV  
lamp, there are lamps with chip on the bulb that stop working if  
output below certain level... but pricy.. The lamp usually degrade  
and adjusted time required to ensure the curing to have same dosage  
of UV... majority of the UV lamp system do not have feed back system  
to check the output... therefore, you got inconsistency of the cure  
even for the same material.  (one that differentiate between the  
Japanese product vs chinese one is the UV cure material and lamp  
system, if you buy the same material, using different curing, you can  
get completely different  stuff in terms of reliability and  
durability).  - not mention some asia region steal the chip on top  
the lamp and glue it on to other cheap lamp as counterfeit... scary  
stuff out there...
On Jul 18, 2017, at 11:24 AM, Dwight Mattix wrote:

> Worked with elastomeric keypads and supplier quality issues in the  
> past.   You'd open up a phone with an inop keypad and find it a  
> sticky mess. Undercuring was the most common cause.  You'd get into  
> the factory offshore and find them either stacking in depth to move  
> more product or cutting down on cure time or both.
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of James Head
> Sent: Tuesday, July 18, 2017 8:01 AM
> To: [log in to unmask]
> Subject: Re: [TN] Fitbit watch band
>
> I've seen the stickyness of silicone products myself on a few items  
> that I've purchased. It don't think it's the humidity as these  
> items were stored in a dry drawer in the house, but not used for a  
> while.
>
> With regard to Silicone it comes in two types as I understand from  
> a chemist I used to work with: cured and uncured. The uncured  
> silicone gives off vapours that poison gas detection sensors for  
> flammable gasses (Pelistors). This I do know after working at Crowcon.
>
> James
>
> James Head BEng MIET CID+
>
> James Head PCB Design and Engineering
> 11 Charmind Walk,Winterbourne Road, SWINDON, SN25 1QA
> Telephone: 01793 266237
> Mobile: 07870 945579
> Skype: headjames
> E-mail: [log in to unmask]
> Website: www.jameshead.co.uk
>
> On 18 July 2017 at 16:01, Yuan-chia Joyce Koo <[log in to unmask]>  
> wrote:
>
>> correction, now think back, I did wear it during shower... so it most
>> likely exposed to soap or shower gel... jk
>>
>> On Jul 18, 2017, at 10:51 AM, Yuan-chia Joyce Koo wrote:
>>
>> the problem is mould release silicone, i believe it is small molecule
>> and
>>> easy to migrate and contaminate parts or assembly.  I didn't realize
>>> lance armstrong bands are part of that... it did degrade after few
>>> years of use... I got two, one become somewhat sticky (never
>>> intentionally exposed to any chemical or put in  to laundry  
>>> machine).
>>> so there are two issues (IMHO), one  is  the mould release, the  
>>> other
>>> is the stability of the silicone  band  - many watches use that, not
>>> just fitbit... look like your customer do have a point...
>>> regards,
>>>       jk
>>> On Jul 18, 2017, at 10:23 AM, Sue Powers-Hartman wrote:
>>>
>>> Thanks for the reply Steve.
>>>> We had a military customer some 10 years ago specifically call out
>>>> the Lance Armstrong bands. They did not want anyone working on  
>>>> their
>>>> product to wear those silicone bands.
>>>> My understanding is that the Fitbit bands are made of elastomer
>>>> material and am not sure what makes that different than silicone.
>>>> When I look that up, it says that an elastomer is a silicone. The
>>>> feel of the two are very different.
>>>> Many at work wear Fitbit watches. But there are several  
>>>> individuals,
>>>> one of who is an engineer, that believes any one working on the
>>>> production floor should not wear one.
>>>> I am looking for a definitive answer, but have not been able to  
>>>> find one.
>>>>
>>>> Sue
>>>>
>>>> From: Steve Gregory [mailto:[log in to unmask]]
>>>> Sent: Monday, July 17, 2017 4:26 PM
>>>> To: TechNet E-Mail Forum <[log in to unmask]>; Sue Powers-Hartman <
>>>> [log in to unmask]>
>>>> Subject: Re: [TN] Fitbit watch band
>>>>
>>>> Hi Sue,
>>>> Here is something you might read. It may have something to do with
>>>> this NASA advisory from a while back...
>>>>
>>>> http://www.spaceref.com/news/viewsr.html?pid=16511
>>>> Steve
>>>>
>>>> On Mon, Jul 17, 2017 at 4:03 PM, Sue Powers Hartman
>>>> <[log in to unmask] <mailto:[log in to unmask]>> wrote:
>>>> Several individuals have asked me if the Fitbit watch band is a
>>>> danger if around the manufacturing of circuit cards, since the band
>>>> is a type of silicone. Does anyone have an answer to this.
>>>> Thank you
>>>>
>>>>
>>>>
>>>> --
>>>> Steve Gregory
>>>> Kimco Design and Manufacturing
>>>> Process Engineer
>>>> (208) 322-0500 Ext. -3133
>>>>
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>>>