CHARLOTTE, N.C. (AP) — Shares of Polypore International Inc. tumbled on Wednesday, a day after reporting that its net income fell 30.5 percent in the second quarter as sales declined for a variety of products.

Its earnings missed Wall Street estimates, and its shares briefly fell to their lowest level since late 2010 before recovering some lost ground.

The Charlotte, N.C., filtration company reported after the market closed Tuesday that its net income fell to $20.5 million, or 43 cents per share, for the April-June period. That compares with $29.5 million, or 63 cents per share, a year ago.

Excluding litigation costs and other special items, Polypore said it earned 51 cents per share in the period.

That still fell short of Wall Street earnings estimates of 53 cents per share, according to FactSet.

Revenue fell by 5.4 percent to $185.8 million. Analysts expected revenue of $184.6 million.

Polypore said that sales fell 5.1 percent in the period for lead-acid battery separators, and they fell 6.7 percent for lithium battery separators. Sales of health care products also dropped 4.7 percent.

"We expect sales and earnings to improve in the second half of 2012 compared to the first half," President and CEO Robert Toth said.

But its shares fell by $4.92, or 13.2 percent, to $32.24 in trading Wednesday after falling as low as $31.50 earlier in the session, their lowest level since November 2010.