Complex sentence: In the past, ships had to be cleaned using abrasives or solvents that were able to cut successfully through embedded grease and grime; however, past solvents were so dangerous to workers that Burton was motivated to finding a solution that was effective and less caustic.
Split into simpler sentences: In the past ships had to be cleaned by one of two methods, abrasives or solvents, that were able to cut successfully through embedded grease and grime. Past solvents were so dangerous to his workers that he was motivated to finding a solution that was effective and less caustic.