Name: Jeffery
Message: I am in the business of selling Polyurethane Foam Pre-Filters for aquariums. I have a Patent Pending on one of my filters and to increase sales I would like to offer a variety of colors. I have tried dying them with Rit and Tintex dyes and it works for a while but after about a week the color fades and then disappears. Will your product last in a water (Aquarium) environment? I know Polyurethane can be permanently colored I just need to find the right type of non toxic dye. The color doesn't have to last forever but a few months would be nice. Can you help me?

I don't know what exactly you are referring to as 'my product', but it does not matter since, as far as I have been able to determine, there is no way to dye polyurethane after-market that would be suitable for your purposes. Polyurethane is dyed in liquid form, during the manufacturing process, before the polymer material is extruded or cast into a solid form.

The acid dyes in all-purpose dyes such as Rit and Tintex can be used to dye polyurethane, if the water temperature and pH of the dyebath are correct, but they will not dye permanently enough for use in an aquarium. Some of the dye will wash out in the aquarium water. I can't recommend that you dye your own polyurethane foam for long-term underwater use. Unfortunately, dyes used for polyester or for acrylic do not work well on polyurethane, either.

In order to sell polyurethane foam pre-filters with a permanent color, you will need to purchase your polyurethane already dyed.

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