Blister foil, primarily made of high-grade aluminum, is a critical component in pharmaceutical packaging, providing a 100% barrier against light, moisture, and oxygen. In 2026, it remains the industry standard for maintaining drug stability and ensuring patient safety.

Analytical Method of Blister foil

1.     Description

Check the samples against the current approved specimen / shade card. The printing shall be done on dull side and other side shall be VMCH coated.

For detailed Description Test Procedure – Refer GTP – Description / Appearance Test.

2.     Thickness

• • Cut a piece of 5x 5 cm² or 10×10 cm² of blister foil with the help of scissors or sharp knife.

• • Weigh the piece and calculate the thickness using the given below formula or dial thickness gauge.

Weight in mg

Thickness of Blister Foil in mm           =    —————————————————————-

(Length x width in mm) x 0.0027

3.     Width of Blister Foil

• • Check the width of the reel samples by measuring the dimension in transverse direction using a scale and record the observation.

4.     Grammage of Blister Foil 

• • Cut a piece of 5×5 cm² or 10x10cm² of blister foil being examined using a scissors or knife. Weigh the piece and record its weight in g (A).

• • Then place the piece on a filter paper.

• • Dip a piece of cotton in Acetone and remove the VMCH coating by rubbing the cotton over the foil gently until all the VMCH coating is removed (This is indicated when non-sticky feeling is observed on the foil).

• • Then Weigh the piece of Aluminum Blister Foil.

• • Repeat the above process till the constant weight is observed. Record the weight in g (B g).

Calculate the GSM by using following Calculation.

(A) g x 100 x 100

                                 Total Grammage            =—————————————-  (C)

(Length x width in cm)

(B) g x 100 x 100

                              Grammage of Aluminum =—————————————-  (D)

(Length x width in cm)

5.     VMCH coating

(A-B) g x 100 x 100

                      Grammage of VMCH coating =—————————————-  (D)

( Length x width in cm)

(VMCH Coating – VMCH coating on aluminum foil creates a protective, heat-sealable layer (Vinyl Methyl Cetal Acetate) for applications like pharmaceutical blister packaging, offering moisture, oxygen barrier properties, and durability, often combined with a shellac (HSL) layer for enhanced sealing and bonding.)

6.    Repeat Length

• • Measure the text repeat length with the help of scale and record the observation.

7.    Text Matter

• • Check the text matter with the help of approved artwork.

8.    Ink Lifting Test 

• • Stick a piece of cello tape (about 3 inch) on the printed surface of the foil.

• • Leave it for about a minute.

• • Then Pull out the tape.

• • The printed matter should not be peel off along with the tape and there should not be any distortion of printing matter on the foil.

9.     Pinholes Testing of Blister Foil

• • Collect a full web width sample of approximate one meter in length.

• • Place the sample on the glass platform of the unit then close the upper part of the unit.

• • Then Switch on the unit to glow the lamp.

• • Observe the sample all area, starting from end to another end of the sample.

• • Count the number of pinholes in the sample Pinhole shall be recorded as number of pinholes per square meter in the visual inspection report.

10.    Machine Suitability of Blister Foil

• • Take the trial run of foil and check the sealing and appearance of strip.

• • Sealing should be proper with no smudging or fading of the printed matter.

11.    Visual Inspection:

• • Check the foil for proper packing and cleanliness.

• • The foil roll should be properly packed with polythene and it should be clean.

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