The process of ion-exchange was first observed by a British chemist in 1850. Ion-exchange is a process, by which one type of ion is absorbed into a solid material and replaced by an equivalent quantity of another ion of the same charge. By using this process, we have formulated an advanced decalcification system that removes calcium from bone quickly while leaving superior cellular detail. The I.E.D. Unit incorporates a strong cation ion-exchange resin in a weak acid solution to remove calcium ions from bone, while replacing them with hydrogen ions. The ion-exchange process does not require strong concentrated acid solutions as in traditional decalcification methods, delicate cellular structures remain intact. This can be very important for immunohistochemistry (IHC) procedures, especially for bone marrow. Over decalcification can destroy morphology that may effect the final staining quality and staining intensity for IHC staining. The ion exchange decal method has been shown to provide the best tissue morphology and IHC staining when compared to other conventional decal methods. Results were very similar to EDTA methods, but much faster. Tissues can remain in the I.E.D. solution for longer periods of time without destroying tissue morphology, eliminating the daily solution change, thus reducing the amount of toxic waste.