Makins Clay Extruder - Stainless Steel Edition, Makins Green Ultimate Clay Extruder and Makins Green Plastic Clay Gun Extruder Important Information about Aluminium and Metal Clay When dissimilar metals touch, there can be a corrosive reaction. This is the case if raw aluminium and silver clay are left in contact with each other. Do not leave your silver clay to dry on aluminium foil or an aluminium baking sheet or similar. Do not fire your pieces or dry them on any aluminium surface. Do not use aluminium foil in your metal clay work in any way. Aluminium tools are safe to use if contact with them is brief and they are not left resting on the silver clay. The Green Makins Ultimate Clay Extruder is Type III coloured anodized aluminium which makes the metal hard and affords a lifetime of protection from corrosion. Anodizing is the treatment done to aluminium to keep it from corroding in the elements. The Green Ultimate Clay Extruder is completely safe for use with metal clay. Even if metal clay is left in contact with the Ultimate Clay Extruder until it is dry, there will not be a reaction since the Ultimate Clay Extruder is permanently protected.