Name: sam
Message: Your website is lovely, I didn't know there were other dyes besides RIT...

Would you happen to know what kind of dye is leaves the most repellant stains on plastic? I want to stain plastic, and I'm worried that RIT will fade in the sun, or if water touches it.

A great deal depends on exactly which plastic you have there. The most useful guide is the recycling logo on the bottom, if there is one.

Products marked with the recycle logo containing a number 5 are polypropylene. You cannot dye polypropylene; colored polypropylene was dyed at the factory while it was still in liquid form. A better solution for this type of plastic might be a special paint for plastics, such as Kolorbond (see Parasol, Inc.). I have not used this product, but the manufacturer's claims are encouraging.

Products marked with the recycle logo containing a number 3 are PVC (polyvinyl chloride, or vinyl). PVC can be dyed by dye sublimation, or heat transfer, like polyester. I do not know if it can also be dyed by boiling it with disperse dye plus a carrier chemical, as polyester can. The manufacturer of Kolorbond paint recommends it for PVC as well. Hard plastic PVCs can be painted with a variety of different paints; Better Signs lists a number of them.

Plastics marked with the recycle logo containing a number 2 are HDPE (high density polyethylene), plastics marked with the recycle logo containing a number 4 are LDPE (low density polyethylene), and plastics marked with the recycle logo containing a number 1 are PETE (polyethylene terephthalate - e.g., Dacron, Fortrel, Mylar). These should all dye the same as polyester: see "Dyeing Polyester with Disperse Dyes". It requires either heat transfer, such as by ironing on), or extensive boiling with a noxious carrier chemical.

Nylon plastics are not marked with a recycle logo. Flying discs, such as Frisbees, and harder plastrics, such as lacrosse sticks, are frequently made of nylon. Nylon is much more easily dyed than any of the above plastics, because its chemical structure resembles that of wool. It can be dyed by simmering it in acid dyes. All-purpose dyes, such as Rit, actually contain acid dyes, mixed with another kind of dye called direct dye, so it is possible to use all-purpose dye on nylon. It is not sufficient to paint the dye on cold; the dye must be applied by soaking the nylon in HOT water with the dye. The dye should be washfast to cool water, but it's impossible to predict, without testing, how well a given dye will resist the sun. A number of different acid dyes are listed on my page about the lightfastness of dyes; the 1:2 premetalized dyes (including perhaps the Lanaset dyes) seem to be among the best.

Acrylic plastics, such as plexiglass, can be dyed only with disperse dyes (like polyester) or with a more hazardous type of dye called Basic dye (see "How to Dye Acrylic with Basic Dye"). I do not recommend that you bring Basic dye into your home. It does not belong in your kitchen or living areas, and its lightfastness may be poor. However, it is noted for being very good at staining any plastics or other surfaces it inadvertently comes into contact with. I have read about people using all-purpose dye to stain Lucite, but even with extended heat and time, the results seemed to me to be far from adequate.

All in all, unless your plastic is nylon, I think you might do best to look into a special plastics paint such as Kolorbond. The fact that it is claimed to resist ultraviolet light for two to five years is a major plus. Note that the apparently high prices at the Parasol Inc. website where I found it are in Canadian dollars, and thus not quite as bad as they might be.