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How to check polybags for quality

by Andrew Reich

A. Ways to checking polybags for quality through physical inspection

1.  Hold bags up to direct sunlight and check for areas of non-conformity in texture and color, other areas of weakness.

2.  Seam Quality  – Fill bags with sand and drop onto a hard floor from 0.5, 1.0 and 2.0 meters.

3.  Seam Quality – Cut the bag open at all but one of the seams, pull on the sides of the “opened” bag to determine the seam quality.

4.  Fill with water/sand and hang for a prolonged period of time.

5.  Take just one face of the bag, and rub/pull on the plastic to determine overall strength.

B. Polybag lab testing

1.  Analytic testing to determine if the material used matches the approved material composition.

2.  CONEG testing to ensure bag complies with CONEG heavy metal requirements.

C.  Security

- Warning on the polybag

Depending on the product and the export market, it can be a must. This printed warning prevents children for playing with such polybag.

- Holes in the polybag

It is also convenient to have holes, 2 or 4 depending on the size of the polybag, in order to avoid suffocation if kids paly with the bag.

- Dessicant inside the polybag

A small pack of dessicant prevents humidity inside the polybag. The proper warning DO NOT EAT in several languages must be printed on.

D.  General information about polybags

In examining and communicating about polybags, it is important that you know the product.  Here are the types of polybags, including an excellent Polybag Glossary provided by:

1. Types

2. Closing

- Piece of adhesive tape

The simplest way, a piece of tape joins the 2 edges of the polybag to close it. It may damage the polybag when removing though.

- Self Adhesive closed

The edge of the polybag includes a band of adhesive tape, the polybag can be easily opened and closed, several times if needed. It is usually used with small items.

- Heat seal

Both edges of the polybag are pressed and heated in a machine in order to get them melt. It is a one time use only, once opened it cannot close again.

- Shrink wrap

The package or product is inserted in a machine that envelops it with a polybag, then the machine heat the polybag to perfectly fit to the product or package, like a new skin.

- Zipper

2 small parts on top of the polybag fit into each other to hermeticly seal the polybag. Frequently used in the kitchen to prevent air from coming inside the polybag to fridge or freeze food.

- Zip Fly

For big items like mattresses or blankets, the polybag may have a zip fly.

Andrew Reich is the CEO of InTouch Manufacturing Services, a QC firm that performs product inspections and factory audits in China for US and EU clients. Andrew also maintains a QC-related blog, Quality Wars.

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