FORMULATION:
Basic composition is established across three inorganic oxides:

Silica sand 73%
Soda ash 14%
Limestone 11%

Besides other metallic oxides that contribute in a minor proportion used as colorants, oxidants, reducers, stabilizers, etcetera.
 
COLOR:
The natural color of glass is a hue of green wich can be altred to crystal white by the application of decolorants or to other colors by the application of colorants.

Colored glass may protect contents in a recipient from light in it's different levels depending on the color of the glass. In the critical region of ultraviolet rays (290 to 450 M.N.) only amber and red are really effective.

In the pharmaceutical industry, ultraviolet light can activate certain chemical ingredients or cause degradation or loss of potency on photosenstive products.
 
GLASS DURABILTY:
A characteristic considered of mayor importance in the design of any glass formula is the resistance to chemical attack; condition known as glass durability.

This resistance is measured by the Alkalin (sodium) liberated from a new container's glass under the influence of destilled water, under specific conditions of pressure and heat.

According to the glass used for it's production, glass containers are classified into four types:
 
Type I.- Borosilicate Glass:Glass containing Boron, which makes it a neutral glass, usually used for pharmaceutical containers, such as vials, laboratory ware, ampuls, etc.. It´s special composition gives it great resistance to chemical attack.
 
Type II.- Treated Soda - Lime Glass:Glass treated with with Freon or Sulfur Dioxide and is filled with injectable or drinkable serums. Containers of Type II owe their chemical stability to the dealkalized surfaces thus produced.
 
Type III.- Soda - Lime Glass:The most widely used glass for glass containers. Soda-Lime glass is found throughout the world of food, wine, beer, bottled water, softdrinks, pharmaceutical, cosmetic and perfume containers.
 
Type IV.- Non-Parenteral: Used exclusively for non-injectable products.

 
TOLERANCES AND SPECIFICATIONS FOR GLASS CONTAINERS:
The tolerances are used as a product manufacturing guide to mantain a standard of specifications for manufacturers. In this way, the manufacturer and the purchaser will know thin which ranges they will be manufacturing. The most important point, is for the glass container to fulfill the customer total requirements.
 
FINISH:
Manufacture is mainly for standard screw thread and twist-off caps or closures. Glass Containers meets the international standard of the Glass Packaging Institute and the Official Mexican Norm, among others.
 
CAPACITY:
Is the Internal volume in millimeters and generaly at the base of the finish (Bottom part of the crown) the capacity tolerance would increase in the measure as the size of the container increases.
 
WEIGHT:
There is a fixed relation between the weight and the capacity, capacity being the stricter specification of the two. The weight noted in the design should be considered approximate since it may have the variations necessary for maintaining capacity within the approved design tolerances.
 
THERMAL SHOCK:
The containers manufacured with different types of glass should resist the following minimum changes in temperature (differential in temperature of water from hot to cold):

Borosilicate (typeI): 55°
Sodalime (type II,III,IV): 44°
 
HEIGHT AND DIAMETER:
The containers manufactured with the blow-blow process will always have variations in the dimensions which should be whithin the tolerances indicated in the design and governed by the GPI.
 
RESIDUAL STRESS:
The tension stresses are removed by a heating process called annealing, for which the maximum allowable disk is 4.


The Advantages of Glass:

Glass has the following exceptional characteristics:
* It allows the product contained to be seen.
* It is a completely innocuous material that does not react with the product.
* It is hygienic since it is not porous and this does not allow the formation of colonies of bacteria.
* It is a perfect insulator, giving products longer shelf lives.
* It is 100% recyclable.
* It can be used to store any other product.
* It can be produced in an infinite variety of shapes and sizes.