Glossary, BAG MANUFACTURING

Name: Murapack
Address: Rue du Stordoir 52, Gembloux, 5030, BE
Telephone: 081 61 35 06

Making and selling plastic bags has its own specific vocabulary that isn’t always easy to understand. So here’s a glossary that should help you better understand the terms used in our industry.

Low Density:	High-pressure polyethylene > flexible, elastic appearance Symbol: LD > LDPE (low-density PE)
Sizes:	Width x length x depth > always given in mm.
Extrusion:	Process converting solid plastic mass into a +/- 200°C molten shape that, once cooled, can be produced or converted into usable products.
High Density:	Low-pressure polyethylene > crumpled appearance (supermarket bags). Avoid using these for sharp waste. Symbol: HD > HDPE (high density PE)
Continuous print:	Where the print appears multiple times per bag.
Marked print:	A single centred print per bag.
Metallic-plastic tie:	Plastic strap containing a metal wire. Packs of 20 or 25 pieces. Length: 20 cm - white.
PP tie:	Polypropylene tie of 5 mm in width, bonded to the bottom of the bag (only with bags having side gussets).
Macro-perforation:	Perforation of 6 mm holes.
Micron:	One-thousandth of a millimetre (1 micron = 0.001 mm). e.g.: 25 microns = 0.025 mm and 150 microns = 0.150 mm
Micro-perforation:	Small perforations to remove air (like thumbtack holes).
Polyethylene:	Plastic material derived from ethylene by a petrochemical process (naphtha/diesel > olefin > ethylene > polyethylene). Linear two-dimensional chemical structure, which makes it recyclable. Raw material in the form of granules.
Four-colour process:	Process of overlaying the 3 primary colours (red/blue/yellow) + black, enabling a photo-quality print.
Regenerated:	Recycled polyethylene obtained by cleaning, grinding and melting of manufacturing scrap and waste. Since the waste is of various origins (new and recycled matter), the regenerated matter has variations in colour and porosity. This is definitely a “second choice”. Hence, a consistent quality cannot be guaranteed. Symbol: RG > HDRG and BDRG (or LDRG)
Gusset:	Internal fold(s) (side or bottom) which increase the volume of a bag when opened. (e.g.: 600 + 2 x 200 mm = 1000 mm in width)
Dithered - dithering:	Grid pattern of points of variable size, enabling one to obtain a monochrome shade, i.e. of a single colour (= tone) (see printing).
Corona treatment:	Treatment of the sheath by micro-electrical discharges, making its surface rough in order to ensure the adherence of the printer ink.