White Opacity

[drummerpaco]

Well, does anyone have experience to measure white opacity for flexo/gravure printout?
I just want to know if my methods are OK for measuring opacity %.

We have Xrite 939 for checking Spot color measurement / QC and when I tried to measure Opacity %, then the measurement shows are vary depends on which white/back backing materila that I use.

So we have tried with Xrite 341C (Transimission Densitometer) which I could find the density and opacity %. Is this right tool for measuring white opacity?
I know that i5 or i7 will do the trick but they seems to be very expensive device to purchase at our budget.

Is there another way to measure White opacity?

[Luc St-Pierre]

Keep using your 939. What I do is: First I calibrate. Then I use the dot area function. When the 939 calls for white, measure the white calibration patch, when it call for solid use the calibration black (hole). When it calls for tint place white printed material over the black hole and measure dot gain (how much black you can see through the printed material). The resulting percentage needs to be substracted from 100 (If spectro reads 30%, then 100-30=70% opacity). It works fine for me.

[drummerpaco]

Well, I should try that. thanks.
Some say the white opacity rage for Flexo/gravure is around 48-55.
Is this measurement value comes from similar way of finding white opacity?

[Luc St-Pierre]

45-55% is a good flexo average. For some customers, we have to double-bump to achieve 60-70% opacity. This is often the case when an over-wrap (shrink material) has to hide correctly barcodes on single units inside a multi-pack package.

[drummerpaco]

I tried and I got some values that I think your were refereing to.
Now when I measure that, it comes with measuring (V)-visual, (C)-Cyan, (M)-Magenta and (Y)-Yellow. What color should I choose for reading white opacity?

[Luc St-Pierre]

Black is my pick since you read over the 939 black hole.

[rich apollo]

could you measure density with a polarization filter?