Hello, we are trying to find a good anti slip paint to apply to an external metal spiral staircase which runs down the back of our building to the garden as it gets very slippery when wet. We will be looking to apply it as soon as possible when we have a dry day so we are looking at temperatures now around 13/14 degrees. We are not sure which would be the best to use on metal surface. There is currently no paint on the metal stairs, it is just bare metal. Please can you give me some advice? Many thanks, Sharon