Glaspak - FAQ

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Glass Products - FAQ

FAQ's - Designer Department

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What is the shelf life of glass container?

Glass containers do not have shelf life but it is subjected to 'blooming' (residue formation over a period of time depending on humidity level in storage environment). This effect can be rinsed off with warm water then the glass container is fit for use. Storage period at any length until the packaging material (or pallet) fails then the glass containers inside will break. .

What is thermal shock?

Thermal shock is the cracking as a result of rapid temperature change. Glass and ceramic objects are particularly vulnerable to this form of failure, due to their low toughness, low thermal conductivity, and high thermal expansion coefficients. However, they are used in many high temperature applications due to their high melting point.

Thermal shock occurs when a thermal gradient causes different parts of an object to expand by different amounts. This differential expansion can be understood in terms of stress or of strain, equivalently. At some point, this stress overcomes the strength of the material, causing a crack to form. If nothing stops this crack from propagating through the material, it will cause the object's structure to fail.

Thermal shock can be prevented by:

Reducing the thermal gradient seen by the object, by changing its temperature more slowly increasing the material's thermal conductivity

Reducing the material's coefficient of thermal expansion Increasing its strength

Increasing its toughness, by crack tip blunting, i.e., plasticity or phase transformation crack deflection

Do glass container have resistance to thermal shock?

Most of our common stocks (round bottles and jars) are QC tested from room temperature (depending atmospheric temperature of location) into hot bath of +40 degC temperature.

Can the glass container be lightweighted for pricing?

We do our best in reviewing weight reduction as long as containers meet to minimum load test, impact / pressure test, performance during freight handling and stability on customer's filling line. Glassplants do have limited capability on glass

forming to result even-thickness of glass distribution overall.
Weight reduction will result to shorter and smaller body compared to current container however good possibility for higher packing quantity per shipment.

What gives glass container strength after lightweighting?

We proposed glassweight for glass container to achieve wall and base thickness above the minimum requirement. Even-thickness (glass) throughout the container when it is formed will distribute load / impact (to some extent) evenly absorbed thus preventing breakage.

Why do some glass containers in Flint / Amber / Green colour?

High demand for Flint glass containers especially in industry that emphasise on hygiene. Containers are almost transparent will show the true colour of filled product and any signs of contamination.

Amber containers are recommended for filled product which are sensitive to UV exposure.
Green and/or other colours glass containers are subject to customer's demand and glassplant's available facility and capacity.

What is the critical part of a glass container?

This would be the glass finish to ensure closure application (plastic or aluminum) is secured to prevent leakage and contamination. Customer must highlight to us if the glass container will be fitted with closure inserts and advise their filling nozzle's outer diameter.