A latex balloon neck is pretreated by refreshing a region (18) of the inner surface (16) of the neck. The refreshed region extends substantially entirely around the inner circumference of the neck. The refreshing consists of cleaning the latex surface with a solvent e.g. isopropanol. The balloon neck is sealed by pressing (e.g. pinching and/or stretching) opposed areas of the refreshed surface (18) into direct contact with each other to form a latex-latex bond without requiring any additional adhesive coating. A removable protective tape (20) is placed over the refresched region (18) to prevent the refreshed region from losing its bonding quality. An apparatus/method for preparing such balloons, and an apparatus/method for inflating and sealing the balloons (automatically) are also described.