All-in-one cleaners that clean and condition in one step may be bad for leather. Some contain detergents that over time can damage the leather. Saddle soap is designed to clean and preserve leather. However, in reality saddle soap is not a particularly good cleanser. It must first dissolve its own oils, decreasing its ability to affect dirt and oils in the leather. Saddle soap is also slightly alkaline and alkalinity can damage leather. Another problem arises during application. The instructions for most saddle soaps tell the user to work the lather into the leather. Loosened dirt is suspended in the lather and pushed deeper into the leather's pores. Saddle soaps have been replaced in modern professional tanneries by emulsions which penetrate, soften and condition with greater ease and stability.