A while ago I accidentally got some deet on the plastic crystal of my watch.
The plastic is now a bit cloudy and that part of the watch is difficult to read.

Any suggestions on how to polish the plastic to restore the crystal so I can read the watch??

Thanks!

Don H

DEET and plastic don't play nice. From the REI factsheet :

"DEET is a "plasticizer." It can have adverse affects on most synthetic fabrics (such as rayon or spandex), auto paint, watch crystals, varnished surfaces, golf-club grips, leather and plastic. It will not damage cotton, wool or nylon."

Sorry, I don't think there's a way to reverse it. Can you get a new crystal for the watch, perhaps?

If only the surface of the crystal is etched, you can polish it out.
First use some 1500 grit, wet and dry sand paper and "wet" sand the crystal to remove any deep scratches/etches. Some jewelers use as low as 400 grit. but that cuts too aggressively.
A muslin buff wheel on your bench grinder or Dremel and some plastic polishing compound is required to lightly buff it back to clear. I think Home Depot or Ace Hardware sells both. Go slow with a light touch or you'll melt the crystal.

I second Dryer, just buff it out per his instructions. <img src="/forums/images/graemlins/grin.gif" alt="" />

Thank you!!

I have seen 600 grit wet or dry at the hardware store, I may have to look a bit to find 1500 grit.

Buffing is an excellent idea, maybe I will try that first in hopes that there are not too many deep scratches.

Thank you Paul!

Don (KQ6KV)

Actually it can be found in the plastic model section of most department stores or go to a hobby shop and they should have it as well. I have some and I think that I got mine in the paint section of Wal-Mart.

No problem Don. <img src="/forums/images/graemlins/smile.gif" alt="" />

If you'll look in your area under Auto Body Paint supply stores, they carry wet/dry paper up over 3000 grit. NAPA auto stores have fine grit papers in their body repair sections.
If you get up above 2000 grit, you might not need to buff it with anything but paste and a soft cloth.

If you don't have a buff wheel, or Dremel, you can do it with wet newspaper charged with plastic polishing paste. Wet the paper, one sheet, (or thin cotton cloth) and stick it down to a flat surface. Charge it with some plastic polish. Lap the watch crystal by holding on to the watch and working the watch in a figure 8 pattern. Rotate it 1/4 turn every few laps. I've polished telescope secondary flats this way. This actually works very well and is safer than a buff wheel. (no risk of burning the plastic)

Be aware that Dryer examines his knife edge under a microscope. <img src="/forums/images/graemlins/cool.gif" alt="" />Even Lapidarists rarely go beyond 1000, unless its diamond grit on a buff. Depending on how deep that clouding goes you may need to start coarser. I'd try it with the 600 and see how it goes. You may need to go to around 400. You can go directly from 600 to polish. Just be sure to keep it very wet while you sand. If the watch is water proof submerge it in water to sand it. The cleaner (better washed) the sanding area the fewer scratches you'll get. When the sanded surface looks perfectly even, try a buffing wheel, lightly, with most anything over 1000, OR a polishing compound, meaning actual polish on the buff. Or sand it and squirt a shot of clear paint on the crystal, just keep it in a dust free dry spot to air dry with good ventilation. <img src="/forums/images/graemlins/grin.gif" alt="" />
Jim <img src="/forums/images/graemlins/cool.gif" alt="" />

Careful there, dullknife, I've got some 2000 grit w/d that cuts faster than standard 600...no kidding! Since we are talking about optics here (loosly defined) I'd err on the side of going too fine instead of too coarse.
The wet newspaper with polish trick is probably safer and easier than using sandpaper.

Of course he could flame polish it too, but that requires a bit of risk taking. <img src="/forums/images/graemlins/grin.gif" alt="" />

I guess since I'm so picky about micro inspected knife edges, he should not be satisified with that watch crystal until it passes a 1/8th wave Foucault test. <img src="/forums/images/graemlins/grin.gif" alt="" /> <img src="/forums/images/graemlins/grin.gif" alt="" /> <img src="/forums/images/graemlins/grin.gif" alt="" />

Off to the auto or model store.

When I am done, I will have the flattest and shiniest watch in town!!

Thanks for the help. It is nice to know it can be fixed. I was feeling really dumb for having clouded it up.

Don KQ6KV

Use a picaridin-based repellent. My old PDA has permanent fingerprints because of DEET. Switched to Cutter Advanced in the pump bottle. Just dump some into an old eye drop dispenser bottle and that's enough for a week. No more problems with plastic or that DEET smell!

Oh, dear God, listen to lori. Deet dissolves plastic! Deet can damange packing straps, sunglasses, and all kinds of synthetics. I thought "Wow, 29% deet works, let's try this 99% deet." I have permanent fingerprints embedded in a plastic clip board, and I dissolved part of my steering wheel.

Yep, DEET dissolves plastic - and 29% deet works on regular bugs - the kind I'd just use the picardin based stuff for. On the other hand there are times in the rockies in june/july, the bugs are the type that will stop your trip cold, and drive you to distraction close to suicide - those are the kind of bugs that you want 99% for. and you just be real real careful around anything plastic <img src="/forums/images/graemlins/smile.gif" alt="" />

I learned the lesson the hard way. I applied the stuff (spray) while sitting in my truck with the door open. It got on my dash and displays. It looks like someone smeared up all my plastic. Oh well it's a work truck now anyway.