Tristel's chairman Francisco Soler has been adding to his stake in the infection and contamination control products supplier.He took 50,000 shares at 41.5p a time, spending more than £20,000.The purchase was drop in the ocean compared to his previous holding. He and his family now own a combined 7,471,477 shares in the company, which amounts to 18.8% of Tristel.Soler, who is a Knight of the Order of Malta, is a founding shareholder of Tristel. He is also chairman of the Bank of Miami and was previously chairman of Leisure Tennis, which used to own the Harbour Club leisure facility in central London.Top Director BuysTristel (TSTL) Director name: Mr Francisco Angel SolerAmount purchased: 50,000 @ 41.50p Value: £20,750Top Director SellsElementis (ELM) Director name: Mr David DutroAmount sold: 1,774,318 @ 155.00p Value: £2,750,193Elementis (ELM) Director name: Mr Brian G TaylorsonAmount sold: 1,754,498 @ 155.00p Value: £2,719,472