This week, 5 Chemicals stocks are improving their overall ratings on Portfolio Grader. Each of these stocks is rated an “A” (“strong buy”) or “B” overall (“buy”).

Stepan Company (SCL) earns a A this week, jumping up from last week’s grade of B. Stepan Company produces specialty and intermediate chemicals that are sold to other manufacturers. The company also gets A’s in operating margin growth. For more information, get Portfolio Grader’s complete analysis of SCL stock.

Ciner Resources LP’s (CINR) ratings are looking better this week, moving up to a A from last week’s B. The company also gets A’s in return on equity. For more information, get Portfolio Grader’s complete analysis of CINR stock.

This week, Tredegar Corporation (TG) pushes up from a C to a B rating. Tredegar Corporation manufactures plastic films, elastics and laminate materials, mainly for personal and household care products and packaging and surface protection applications. The company also gets A’s in earnings revisions and earnings momentum. For more information, get Portfolio Grader’s complete analysis of TG stock.

Kronos Worldwide, Inc. (KRO) boosts its rating from a C to a B this week. Kronos Worldwide, Inc. produces titanium dioxide pigments. The company also gets A’s in earnings revisions, earnings surprise, and earnings momentum. For more information, get Portfolio Grader’s complete analysis of KRO stock.

This is a strong week for Valhi, Inc. (VHI). The company’s rating climbs to B from the previous week’s C. Valhi, Inc. is in the chemicals and waste management business. The company also gets A’s in earnings momentum. For more information, get Portfolio Grader’s complete analysis of VHI stock.

Louis Navellier’s proprietary Portfolio Grader stock ranking system assesses roughly 5,000 companies every week based on a number of fundamental and quantitative measures. Stocks are given a letter grade based on their results — with A being “strong buy,” and F being “strong sell.” Explore the tool here.