Baptism robes are attires, normally worn by initiates when they are being baptised into their religion. They are often white but pink robes are intended for girls and light blue are intended for boys are there are plenty available.
There are some garments worn with regard to adult baptism. They are usually made to get wet because baptism is by immersion of the whole body in water. Baptism robes are normally white and look like choir gowns without any ornamentation. Nowadays very few people have got the inclination and time to design and make baptism robes. There are internet sites that promote exclusively these robes and also other baptism attires for girls and boys.
A baptismal robe can be stored in great quality archival box that can protect it from the damage of time so it can be passed on from one generation to another. Such special boxes are normally sold through the same sites that are selling the robe.