Actavis tube cap

Actavis cap narrow side up — Actavis tube(left), twist-on cap with side-to-attach-to-tube facing up(middle), twist-on cap with side-to-attach-to-tube facing down(right)

The design of this Actavis cap has both good qualities and problematic ones.

Good Aspects

The discoverability of opening and closing the tube: the ridges on the cap provide grip and make it obvious that one is supposed to twist the cap to open it, leading to great learnability
There is immediate feedback when opening and closing the tube: The resistance increases when twisting to close and decreases when twisting to open.
Constraints prevent one from opening the tube incorrectly: pulling and pushing the cap to open and close does not work

These visual and tactile cues lead to immediate understanding of how to use the cap.

Problem

The problem with the design of the Actavis cap is that the diameter of the side that attaches to the tube is smaller than the side that faces away from the tube. For most tubes with twist caps, the opposite is true. One repeatedly makes the mistake of attempting to twist the cap using the wrong side when closing the tube after use. This design choice leads to a loss of efficiency, because the side of the cap to twist on goes against the already well established conceptual model of a twist-on cap.

Solution

The solution to this flaw in design is simple: increase the diameter of the side of the cap to twist by adding more plastic such that the diameter is larger than the opposite side. Maintain the ridges on the outside of the cap and the general shape. This allows the diameter of the opening of the tube to remain the same.

In this way, the natural mapping from the concept of side-of-cap-to-twist-on to successfully closing the tube is reestablished.

Actavis tube cap

Good Aspects

Problem

Solution

go back