How to detect presence of metallized paper? 3

[parobellumx]

I am trying to develop a method to detect when packaging is using metallized paper. I tried a multimeter and got nothing (aluminum plus lacquer layer is likely problem).

Metallized paper is a multistep/multilayer process that is typically as follows:

1. paper substrate

2. thin varnish layer to prepare surface for metallization

3. aluminum vacuum metallization layer of 0.08 to 0.1 g/m2

4. Thin lacquer layer

Any thoughts on tests? Essentially I want to test for the presence of aluminum.

 

[patprimmer]

Can it be destructive testing.

If so, atomic absorption spectrophotometry should detect aluminium.

http://en.wikipedia.org/wiki/Atomic_absorption_spectrophotometry

Regards
Pat
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[metengr]

Agree, AAS would be definitive and would only require a small sample.

 

[cloa]

Some sort of inductive detector would do it too.

http://www.alibaba.com/showroom/pulse-induction-metal-detector.html

 

[parobellumx]

Great suggestions - anything else? Could I use something acidic that would destroy nonmetal but leave the metallization unharmed (thus proving there is metallization)?

 

[IRstuff]

X-Ray Fluorescence can be used to detect thin layers of aluminum and other metals:

http://xcaliburxrf.com/cal_std_guide.html

http://www.oxinst.com/products/coat...-control/cmi900/Documents/cmi900_brochure.pdf

TTFN

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[patprimmer]

Both acids and alkalies attack aluminium so that is no help.

My chemistry is to rusty to remember how to dissolve aluminium in sodium hydroxide then precipitate it out prove what it is. Someone up to speed on chemical analysis could help, but if the layer is really thin, you might not have enough to get a result and the lacquer might interfere. A solvent like acetone or methylene chloride might strip the lacquer off, but this might also leave such a fragile film that it cannot be analyzed

Regards
Pat
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[Ron]

Use a small, two prong moisture meter. It is a conductance meter and the aluminum in your sandwich is the only truly conductive material. There is a type of same than used induction as well.

Look at Delmhorst or GE Protimeter.

 

[Ron]

Another possibility is to put it in a microwave oven. It should spark. This is similar to the "browning" cartons that come with some microwavable products.

 

[arunmrao]

If you could check for capacitance as is done in paper capacitors or a UV kit built for testing . These are wild thoughts.

_____________________________________
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[Ron]

Oops! Not conductance....it's a capacitance meter. Thanks arunmrao for triggering my sprained brain!

 

[jim07601]

An eddy current meter might work. Alternatively, if you move the paper, it might generate a small magnetic flux.