We recommend using a gas that contains 95% Argon and 5% Carbon Dioxide for any welding less than 6mm.
Gas MIG welding will always give you the best results, the MIG181 also supports gasless MIG wire, this is ideal if welding outside or where gas is unavailable.
Gas bottles can be purchased from many outlets and you have option of buying the bottle and gas, when bottle is empty - return bottle for a fully filled one, this is generally know as 'rent free bottles'
For high / industrial use, you can purchase via a rental agreement normally paid by direct debit - more cost effective for high volume users.