Sighting in a thermal scope

[marcm1]

I use a golf ball wrapped in electrical tape I sighted my halo xrf in at 200 yards I heated it up with car vent glows great, you can also
Just do a cross with the electrical tape it works best for me
This is a 200 yard target just resting my zero

 

[JustMe2]

Foil tape(duct tape) is your friend. Hand warmers will bloom pretty bad and transfer heat to your target

Foil is what I use also. What the foil is actually doing is reflecting the sun's heat or the cold sky like a mirror and not being heated by the sun. So when you set up your foil target, lean the target back slightly so the entire target is fully illuminated by the sun. It should not shade itself by leaning the target board towards the ground. Remember, your thermal scope sees heat, not light nor color like your eyes see. Different colors absorb the heat from the sun to different levels of intensity like a black car or white car in the summer sun. Consequently, black tape on a white background will each heat differently which you will see in the thermal scope.