Zoltek's (Nasdaq: ZOLT) second-quarter results came loaded with more than a few surprises. The company, which manufactures carbon fibers, saw its sales surge 42.5% compared to the same quarter one year ago. But to investors' chagrin, it failed to convert those incremental revenues into income, sending its stock down substantially.

The numbers
Amid recessionary conditions, Zoltek managed to report this huge jump in its net sales despite recording a drop in sales to its largest wind turbine customer, Vestas. Net sales in the second quarter of 2011 stood at $37 million, compared with $26 million in the year-ago quarter. Not too shabby.

The rise in top-line figures was helped by growth in the wind turbine operations as well as implementation of higher prices during the second quarter. Zoltek remains bullish on that front as it sees a general upswing in sales throughout the entire fiscal year, helped mainly by an expected surge in demand for carbon and technical fibers from the wider wind energy industry.

Looking toward the bottom line, rising costs, losses on foreign currency transactions, and losses on liabilities weighed on the company. On a sequential quarter basis, the company's net loss increased by $0.1 million. In comparison, its competitor Hexcel (NYSE: HXL) posted a 67% jump in its net income during the quarter. Clearly investors have expected the company to begin translating strong top-line growth with more impressive returns in investment.

Extra work for the company
Zoltek, whose fibers are also used in the aviation industry, is seeing increased competition in the aerospace segment from Hexcel and Cytec Industries (NYSE: CYT) alike. Things are clearly heating up in the industry.

For now, Zoltek is a mostly North American-focused company. Although Zoltek has taken steps to expand operations beyond the U.S. and Mexico -- and seen some success in emerging markets, including China and India -- broader concerns still remain intact.

For instance, Zoltek has been showing negative earnings since 2009. Amid hopes for economic recovery and improved market conditions, investors appear jittery about the company's growth prospects.

The Foolish bottom line
For now, the stock doesn't appear attractive enough for me to consider investing. Yes, strong top-line growth is nice and I'm interested in investing in industries that are being buffeted by larger economic tailwinds. But I think it'd be prudent to wait for the next quarter's results to get a better sense of the company's growth prospects.

What do you think about Zoltek's future? Give us your Foolish opinion in the comments below.

Anupama Pattanaik doesn't hold shares of any of the companies mentioned in the article. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.