Torvald Helmer's character is defined by both the pressure he puts himself under and the pressure of society that he feels it is necessary to conform to.  This article of clothing, the old diving mask, represents the pressure Helmer puts himself under as he needs to build up his reputation to the point where he isolates and eventually ruins himself. In addition, it expresses the idea that Helmer's heart, unlike the rest of his shielded body, is neglected and vulnerable.

He has built up a his reputation by ensuring he has "a safe, secure job" and makes sure that his family does not do anything to destroy results of the precautions he has taken. He even breaks ties with people who are immoral because he feels "revolted when [he's] anywhere near " such people (1583). Yet all of his attempts to fortify himself fail in the end, when he is faced with ruin so great that he actually seems to crack.  The cracks in the mask demonstrate this emotional breakdown. The heart, on his sleeve, shows his vulnerability to outside forces.