Where exactly to take temps on a UTH

Ok so I got a question for you guys who have run UTH on aspen for awhile. Do you guys take the temp from the glass under the aspen or on top of the aspen? My heat mat is set to 96 degrees between the mat and the tank bottom but when I temp gun it from up top on the aspen, it is 86 degrees. Then if I dig down to the bottom of about 1/2 inch of aspen and temp gun the glass there, it is 96 degrees, the same as my setting and probe reading. Now people say 88-90 degrees, are they talking glass temp which would put the aspen at pretty much nothing or are they talking the glass temp ie the hottest spot the snake can ever get to? I ask cause im wondering if I should bump the heat mat temp up some to achieve that 90 degree warm spot on top of the aspen.

Given that the snakes can push the substrate out of the way, I think in would mean you need to take temps directly over the glass to know whether it's in the safe zone or not. If it's a bit cooler on top of the substrate, that shouldn't hurt anything as long as the over all ambient temperatures for the snake's enclosure are within the acceptable range.

You want to monitor the temp EVERYWHERE.

The substrate over the uth should only be a 1/4 at most. This makes it easier for the heat to pass through and reach the snake.

You want to monitor the temp on the bottom of the tank and make sure it does not get to hot but you also want to monitor the heat on top to make sure your substrate is not to thick and stealing the heat.

I have my uth temp on the surface 90-92 degrees and on top of the substrate is whatever if he wants it warmer he moves the bedding I never take temp on the bedding... Plus once the bedding has the snake weight on it the heat will transfer better always go for the surface of the enclosure

You want to know the temperature of the surface your snake can touch.

Thanks all. Yeah I grabbed Dot and then pushed all her aspen out from the UTH and temp gunned the whole thing and it sits around 94-95 degrees. Then I re-covered the glass with the thin layer im using and put her hide back down. So it seems its ok and after that, Dot crawled back into her hide. Then I rewarded her with her rat pup which she almost took my finger with it as I was putting it down in front of her hide :P