I am doing a bit of decorating and have v little money. I can't afford new flooring. I have old (probably 30 years) what I presume are vinyl tiles - a bit scratched in places but i have discovered with a bit of sugar soap and some elbow grease they come up quite clean. BUT spaces between the tiles are full of dirt - I can scrub it out but i can''t find any grout that is marketed as suitable to refill the gaps - any ideas? Will it matter if i use a grout that is intended for ceramic or stone tiles? Can i just use caulk?