Heat rejection test for windshield tint: (design & result)
 

Help design a test of heat rejection benefits of heat rejecting windshield tint.

I have applied this office/residential heat rejecting tint to my windshield. At 70% light transmissivity it should be legal in most jurisdictions, and anyway I can see through it excellently day and night.

https://ecomodder.com/forum/attachme...1&d=1589135820

Its maker claims it rejects about half the heat and nearly 100% of damaging UV light. I applied it imperfectly and need to do it again. But first, I think I will peel off half and do a side-by-side test of how well it rejects heat on my dashboard. Is there an affordable tool that you know to be good quality that I might buy to test with? Are there cheap hacks like melting wax in two cups on the dash, one under the tint and one not?

Thanks.

Buying a tool such as one of these seems plausible. Some are kinda expensive and I would not trust that FLIR thing. Anyone have a preferred scanner? Know the best one, or ones?

https://ecomodder.com/forum/attachme...1&d=1589154261

I imagine taking readings of two specific points on the dash every 3 or 5 minutes to see how temperature changes over time. I wonder about heat being transmitted across the dashboard however, so that my readings are confounded. Probably that would happen slowly though, with minimal effect. Thoughts?

Scanners are overkill. Search infrared thermometer. I have one that I bought years ago and it has worked, and still works, very well. The absolute accuracy is not all that great, but it's usually within 2 or 3 degrees F. The relative accuracy, where you want to know if one place is warmer than another, is better. I see that Home Depot has them for as little as $30.00: https://www.homedepot.com/p/Klein-To...-IR1/313516785.

Dashboards are plastic, which is a poor conductor of heat, so heat conduction from the hot side will be slow.

Thanks. I like that one. Thinking future, I could spend $70 and get one with a higher temp range. I see some at Home Depot that brag about emisivity abilities and 1200 F high temp readings... could montior catalyst temps with a thermometer like that...
EDIT: Pulled the trigger and bought General Tools Industrial IR Thermometer with K Probe and Adjustable Emissivity. Great temp range in IR and the K-Probe and emisivity options seemed interesting. Paid $76... I can live with that. I'll use this for a few types of measurement tasks.

More thoughts about this test planning and a question.

The plan: remove the passenger side of the windshield tint and use an IR Thermometer I am waiting to receive to measure differences in heat on the two sides of the dashboard. I will observe temperatures over several hours to capture not just a moment but the relative rate of change over time.

When I do the test, I think I should (1) park the car facing the rising sun and (2) have both windows cracked open in the same way I have them while driving around in the summer. Open windows mimics my real conditions, but it also might prevent ambient temps inside the car from warming both sides of the dash equally. Does that sound right to people? I could do both open and closed window tests on successive days. Does it matter?

...and now, back to work...

I don't really see the point of doing this testing yourself when brand name automotive window film makers have detailed numbers published on UV/IR/visible light transmission. As far as I'm concerned, if you live in a sunny place like CA, it's a no-brainer, and every single window needs it.

My personal preference is Llumar Air 80 all around, maybe 90 on the windshield. It's cheaper than 3M Crystalline or Photosync, and the 80 is about the optimal level of light transmission for me. I tried Crystalline 70 on the windshield of my FRS and at times I felt like it was hard to see at night.

The difference between having Crystalline 70 or Air 80 and nothing is like night and day.

So, I take your point. I should explain the goal a little more. Since I used residential/commercial tint and not automotive tint (cheaper by far!) I thought it would matter to confirm effectiveness. Also, since I am using it for seriously needed heat abatement in a car with no AC, I thought it would be useful to me and others if I can demonstrate the benefit through measurements of the heat on the dash. My dashboard becomes a ~180° or more space heater in peak summer. If I can pring that down 30 or 50° I will feel successful because cracked-open & fully-open windows will work a lot better.

EDIT: I wouldn't be testing it but for the fact that I have to reinstall because I did it not so well on my first try. Seems convenient now.