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Why use the Black Cap Design
History of Soft-Drink Bottle Design

Updated October 2003.

WHY USE THE BLACK CAP DESIGN

  1. Great tactile therapeutic stimulator for Visually Impaired.
  2. Stands firmer on surfaces.
  3. Better protection for contents.
  4. Environmentally compliant: Tighter Crushing in Landfills.
  5. Environmentally compliant: Overall less plastic resources used.


One  -  Great tactile therapeutic stimulator for vision impaired.

After the bottles were emptied and washed, the vision impaired or persons sensitive to feel, would gently rub their fingers around the bubbly portion of the bottle, which in most cases was the black cap section.  Unlike any other plastic or material, the black polypropylene used for the caps at the bottom of the bottle, had a unique tactile texture which was extremely light in weight, very thin, soft and smooth.  Because of it's extreme thinness, it's main attribute was a bubbly feel.  As the person presses their fingers into the polypropylene, the p e t plastic underneath would bubble in and out from the moving motion of the fingers. 

As a visually impaired person, gently pressing the plastics in and out would give me the sensation of pressing my fingers into a large plastic bubble.  In-turn this would greatly increase the tactile experience, ultimately giving a sensation of pure pleasure.  Doing this with the larger caps would extend the time period of maximum pleasure, which ultimately became a great therapeutic release.

Two  -  Stands firmer on surfaces.

Complaints are often expressed about the fact that rocket bottles often topple over and are unstable.  The bottles would stand firmer with a black cap glued to the bottom.  The polypropylene cap would make solid contact onto the surface it's standing on, where as only the small tips of the rocket bottom would make contact, making it much more vulnerable to tipping and falling over.

Three  -  Protects contents from leakage.

The polypropylene cap would also guard the most vulnerable part of the bottle from drops and bumps.  Many soft-drink companies bottle their beverages, by pressure filling the liquids into the bottles, to preserve freshness.  The force that is created from this pressure is at its maximum, around the bottom or base point of the bottle.  The specially design cap that would be glued on, would protect this portion of the bottle, by leaving a small buffer space between the PET plastic, and the polypropylene cap. (illustration B on right)  I often visit supermarkets and pick bottles off shelves that contain leaking bottles, from being dropped.  Upon closer inspection, the leaks are always located on the points of the rocket tips.

Illustration B:  Outline Diagram

ENVIRONMENTALLY COMPLIANT


Four  -  Tighter crushing in landfills.

There has been many initiatives from environmentalist and local councils to get local residents to recycle these bottles.  Although many of them are recycled, there is still a large portion of these bottles that get disposed of, and ultimately end up in landfill. Rubbish is rolled and crushed and then berried in landfill facilities across the world.  This process is repeated numerous times over many years, but can be impeded by materials that are not biodegradable, or in the case of the rocket bottle, do not crush completely.

The crushing of these bottles is impeded from what is called the thin and thick issue, which is demonstrated in illustration C.  You'll note that the bottle is made of thinner plastics in the middle section, whilst the plastics on the bottom, where the rocket points are, are much thicker.  In the event of being crushed, the middle portion of the bottle would collapse with no resistance, but the lid and rocket bottom section would hold firm.

Illustration C:  Crushing Principle

Illustration C shows the current rocket shaped bottle to the left.  After crushing, the rocket bottom portion  (marked in white) remains mostly uncrushed.  On the right, the older black cap design is completely crushed.  This is achieved by using a consistent thinness (consistent thin yellow and green line), through the entire bottle shape.  This includes the bottom of the P E T Plastic bottle, and the polypropylene cap.  Over a period of time, it would be possible to compact more rubbish into land-fills. These bottles would crushed easier, as there is no resistance from thicker parts keeping their shape.

From the perspective of recycling, the extremely thin polypropylene cap would be easy to pull off, as it would be stuck to the bottle with one small dab of glue. (marked in blue)  Both the polypropylene and P E T Plastic would be recyclable. 



Five  -  Less plastic means less use of raw resources. 

The cost of using this black cap bottle would be the same as using the rocket bottom design.  Although a initial cost may result from adapting bottle molding facilities, the long term costs should equal the current costs of manufacturing the current design.  Some bottle molding factories may still have these facilities, from making the original black cap bottles in the 1980's.  This is achieved by using less plastic in the PET Plastic portion of the bottle, and using the remaining funds for making the polypropylene caps, and ultimately putting less pressure on land-fill facilities and most importantly using less raw resources.

Illustration D demonstrates the amount of plastic used for both bottle designs, and how using the polypropylene capped design would use less plastic.  We will assume it would take 30 units of plastic to make the current rocket shaped bottomed bottle.  This would result in 30 Units of P E T Plastic in total.  The black cap design would use only 25 units in total.  This is achieved by using a rounded bottom, rather then the rocket.  As shown in illustration F, the layer of plastic would be much thinner, and the surface area of the base would be greatly reduced, in-turn reducing the amount of plastic used, in the most resource consuming part of the bottle.  This would calculate to around 20 units of PET Plastic for the main bottle portion, and 5 units used for the polypropylene cap.  This would also result from the pet plastic portion measuring less in height.  A rounded bottom would hold more liquid then a rocket bottom, therefore reducing the bottles overall height. 

The red column denotes amount of P E T Plastic used wile the blue column denotes amount of polypropylene used

Illustration D:  Amount of Plastic Used

Illustration E demonstrates the surface area of a rocket bottom bottle is twice that, (most probably more) then a  rounded bottom.  The combination of more surface area and thicker plastics around this portion of the bottle, demonstrates a heavier use of resources.  The diagram below shows where the plastics are thicker. (dark green), and where they are at there thickest (yellow and white).  The entire bottom of a rocket bottom bottle uses thicker plastics, whilst only a small portion of the rounded bottom, uses a small thick spot, (needed for pressure packing).  The rest of the black area (gray ring on right with green dot), shows that most of the P E T Plastic base of the rounded bottom is the same thinness as the rest of the bottle. This aspect is also shown in illustration F.

Illustration E:  Surface Area of Bottle Base (P E T Plastic Portion)

Illustration F: Diagram of bottle bottoms

Conclusion


  1. Great tactile therapeutic stimulator for Visually Impaired.
  2. Stands firmer on surfaces.
  3. Better protection for contents.
  4. Environmentally compliant: Tighter Crushing in Landfills.
  5. Environmentally compliant: Overall less plastic resources used.

During the 1990's, I received correspondence from management of plastic molding companies, noting that the original black-cap bottle (two piece design) was more demanding both economically and environmentally.  As explained in the history of soft-drink bottle design, both concerns were initially justified.  As demonstrated in this website, the benefits of using the new generation black cap design now greatly out-weigh the original concerns noted during the early nineties. 

PLEASE WRITE LETTERS OF SUPPORT


The reasons discussed throughout this website give nothing short of the best case, of why there is the need to make these changes as soon as possible.  I would like to use this web-site to URGE the soft-drink companies as much as I can, to please, please, please, do away with the current rocket bottom bottles and adopt the black cap design.  Any letters of support for the "black cap" design can be mail to mark@2prfm.com.  Any feedback or comments are welcome.