The grades of four chemicals stocks are on the rise this week on Portfolio Grader. Each of these stocks is rated an “A” (“strong buy”) or “B” overall (“buy”).

Platform Specialty Products Corp. (PAH) is bumping up its rating from a C (“hold”) to a B (“buy”) this week. In Portfolio Grader’s specific subcategory of Earnings Surprise, PAH also gets an A. For more information, get Portfolio Grader’s complete analysis of PAH stock.

This week, Valspar Corporation (VAL) pushes up from a C to a B rating. Valspar is a coating and paint manufacturer and distributor. For more information, get Portfolio Grader’s complete analysis of VAL stock.

ForceField Energy Inc. (FNRG) is progressing from last week’s rating of B (“buy”) as the company improves to an A (“strong buy”) this week. Shares of the stock have been changing hands at an unusually rapid pace, twice the rate of the week prior. For more information, get Portfolio Grader’s complete analysis of FNRG stock.

Potash Corporation of Saskatchewan Inc. (POT) improves from a C to a B rating this week. Potash Corporation of Saskatchewan produces potash, phosphate, and nitrogen to the agricultural and industrial industries worldwide. For more information, get Portfolio Grader’s complete analysis of POT 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.