I buy large volume of PE clear tape / film (approximately 0.003? to
0.004?thick), the film contain UV stabilizing additive to prevent film
and adhesive backing from harmful UV rays.
On many occasions my overseas supplier send inferior PE film that does
not contain UV stabilizer.
The material was initially submitted to all kinds of tests including
accelerated aging.

I have to inspect every roll of film to make sure that it contains UV
additive before I send to my customer.
Since I cannot visually detect the UV additive, is there a quick test
that I can do to assure myself that it contains the stabilizer?
A very good tip to the right answer.
Regards

Hi, 

It sounds like what you need to do is measure how much UV is traveling
through the film. You would need a "Known Good" sample of the film
with the coating you are looking for, and two rather inexpensive
items.

The first is a UV meter which measures the amount of UV light hitting it,

http://www.etacuisenaire.com/catalog/product?deptId=&prodId=23149&wotrl=froogle

and the second is a UV light source which can be directed through the film. 

http://www.nextdaypc.com/main/products/details.aspx?PID=2489063&rsmainid=ND0130014

Using the "Known Good" sample, measure the amount of UV light going
through the film when the UV pen is used. That is your base test
measurement. Any measurement more than that would be uncoated film.

Using these small items you should be able to setup a testing area
which limits the amount of ambient UV light in the room, so that you
don't get false fails.

Thanks, 

webadept-ga

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Request for Answer Clarification by betterbuilding-ga on 07 Dec 2005 09:10 PST

I tried and it works very well.   When the UV meter reads very high,
it means that the UV rays do pass through the film and when the
reading is low, it means that there are little or no UV Rays passing
through the film.  My follow-up question is when it is reading low,
does it mean that the UV rays are blocked or are they simply absorbed
by the film?
Thank you very much

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Clarification of Answer by webadept-ga on 07 Dec 2005 10:40 PST

Glad to hear everything worked out for you. As for your follow up
question, I don't know what you are using for the UV protective
coating, but I would guess that the UV rays are being reflected, and
not absorbed.

You can test this. Just find some film that you know has the
protective coating, take a reading with your UV meter off the coated
side, then shine the UV light at the film. IF it is being reflected
then I would guess that your meter will show a jump in UV rays. If it
is being absorbed, then I would guess that the jump would not be very
great.

Happy Holidays, 

webadept-ga

A simple way to go would be to get a UV tester i/e a spectrometer like 
http://www.mut-gmbh.de/en/products/optical_systems/elemente/technical_data/20021011151600.html
and on the other side shine a UV light on the plastic sheet. If the
spectrometer detects the UV you can be assured the additive was not
used or not in the right quantities.

Also since you have a known power source of UV measuring the amount
that gets through will let you know the amount of the additive used
(provided you know what the plastic's own resistance is).

Eli

even if a little UV gets through it shouldnt be like there hasnt been
any additives used. What would be ideal is to see how much UV gets
through a sample that has lasted to ur satisfaction so take a tape
make it into 2 one part u save (as in preserve) the other subject it
to accelarated aging then if it lasts to ur satisfaction use the
preserved piece to measure how much UV it lets through. It will be
initialy process intensive but once done u will know the average value
the material should let through

The answer and the comments posted here will help me tremendously to
put a proper quality control in place.
I just ordered both the pen (UV light) and detector and will try as
soon as get them.
I will rate the answer as soon as I do my experiments (hopefully
before the end of November
Again, thanks to all and happy Thanksgiving