This week, 4 Chemicals stocks are improving their overall ratings on Portfolio Grader. Each of these stocks is rated an “A” (“strong buy”) or “B” overall (“buy”).

Balchem Corporation (BCPC) boosts its rating from a C to a B this week. Balchem Corporation develops, manufactures, and markets of specialty ingredients and products for the food, nutritional, feed, pharmaceutical, and medical sterilization industries. For more information, get Portfolio Grader’s complete analysis of BCPC stock.

This is a strong week for Koppers Holdings Inc. (KOP). The company’s rating climbs to B from the previous week’s C. Koppers Holdings Inc. manufactures carbon compounds and wood treatments. The company also gets A’s in earnings surprise. For more information, get Portfolio Grader’s complete analysis of KOP stock.

KMG Chemicals, Inc. (KMG) improves from a C to a B rating this week. KMG Chemicals, Inc. is engaged in the manufacture, formulation, and distribution of specialty chemicals primarily in the United States, Canada, Mexico, Europe, and Asia. The company also gets A’s in operating margin growth, earnings growth, and free cash flow. For more information, get Portfolio Grader’s complete analysis of KMG stock.

This week, Sociedad Quimica Y Minera De Chile S.A. Sponsored ADR Pfd Class B’s (SQM) ratings are up from a B last week to a A. Sociedad Quimica Y Minera De Chile S.A. Sponsored ADR Pfd Class B produces and distributes fertilizers, iodine, lithium and other industrial chemicals. For more information, get Portfolio Grader’s complete analysis of SQM 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.