Polycarbonate Stems

[Danskpibemager]

I posted a question about a month ago, asking if anyone had ever tried polycarbonate for hand cut stem material. I think there may have been some confusion on the material which is actually "Lexan". Well, I ordered a 4 Ft. section of 3/4" black rod and gave it a go. The working properties are a cross between acrylic and ebonite and it machines and sands fairly well, much easier than ABS. The stem took about an hour and a half to complete and I went through the typical progression of hand sanding grits and onto the buffer with brown tripoli, white diamond and then Hut Ultra Gloss as the final polish. No such luck for a high gloss finish! The best I can get is a rather dull gloss that is in no way acceptable on a finished pipe. Just thought I'd pass along the info to save others some time and expense.

[wdteipen]

Thanks for taking on the experiment and passing on your findings.

[KurtHuhn]

Lexan is actually a brand name of polycarbonate - as are Calibre, Makrolon, and one other I can't recall. They're similar, but not the same as, acrylic. For instance, polycarbonate, while optically very, very clear (which is why it's used for lenses), is very prone to surface scratches, while acrylic is less prone.

Polycarbonates can be buffed to a super high gloss, but you have to be very careful of your process, and make sure that you really work the sandpaper, especially the higher grits, to get out all the scratches. If it's still not going your way, you could try dipping the piece very briefly in acetone. That will dissolve a top layer of the polycarbonate, and redeposit it very smoothly as the acetone evaporates. The same trick can be used on acrylic.

[Danskpibemager]

Thanks for the information Kurt! I sanded up to 800 grit which is more than I go with acrylic and have glass-like results. I've got a micro-mesh kit that goes up to 12,000 grit so I'll give it another try along with the acetone burn. My initial reason for the test was to find a product closer to ebonite in "Tooth Feel" which it has as well as machining characteristics. I'm wondering if there is a non-toxic coating that can be applied if I ever get the gloss I'm looking for to prevent future scratches.

[Frank]

I'm wondering if there is a non-toxic coating that can be applied if I ever get the gloss I'm looking for to prevent future scratches.

I'm not sure what type of coating you're looking for, but it would need to be really hard. The only thing that comes to mind is resin. It does come in food grade, the kind used for coating the inside of genuine horn used as drinkining horns.

[FredS]

. . . The most difficult aspect of working with polycarbonate as a stem material is that it's hygrostatic. It absorbs water. . .

I think you mean hygroscopic (or even hydroscopic). BTW - Acrylics, nylons & many other plastics are also hygroscopic.