Here is an interesting problem.

[Rolf]

Why not try again......

Well, the marker worked, but not perfectly.....I just moved the damn lamp!

Will look into another bulb when this one burns out.

I could get another trackball, but my hand likes this one. The ball is also the same size as a pool ball.....I replaced it a long time ago with an eight ball and it looks pretty cool!

Felt markers are just ink, why not try spray paint, your original idea, or the electrical tape that I suggested. Ink based makers have a very thin film deposit compared to just about anything else.
You can clearly see the how transparent it is if you hold a paper that has a Sharpie blotch on it up to your halogen lamp. If you have some spray glue then it might be possible to fasten aluminum foil. That would surly do it.

I just hate to see you give up!

 

[GonzoEngineer]

Felt markers are just ink, why not try spray paint, your original idea, or the electrical tape that I suggested. Ink based makers have a very thin film deposit compared to just about anything else.
You can clearly see the how transparent it is if you hold a paper that has a Sharpie blotch on it up to your halogen lamp. If you have some spray glue then it might be possible to fasten aluminum foil. That would surly do it.

I just hate to see you give up!

I didn't give up yet........I just got off work and stopped by the hardware store for a can of spray paint.

Gonna fix this sucker once and for all.

And, no offense Rolf.......but I hate electrical tape.......it always has a mind of it's own, and I don't keep it around!

 

[Hayato]

Besides that, some spray paints have metallic particles, like aluminium, that help attenuate the IR.

 

[glutnix_neo]

You can monitor the signal on the IR sensor if you have an oscilloscope. Covering the lamp with nonconductive material is a good idea, it would isolate the possibility that it is the EMI that it causing it, our hand can shield(or deflect) EMI