Let say first layer is 65% Heat rejection and you install another layer which gives 82% Heat rejection, what's the total
heat rejection?

65+82=147%?

or

65<82% = 82% + 5% = 86.1%?

or


just 82%

Any Window Tinting expert here?

1st tint 65% so left 35% not rejected..
so out of 35% not rejected, 82% will be rejected by second tint.
so after all that the not rejected rate should be around 7%

Sounds logical but is it like that?

not sure but i do think it is safe to think like that..
logically thinking that is

I checked with the tinting shop before, they cannot apply another tint on the existing thin because it won't last & hold.

I've been told depends on the first layer of tinting, if done properly, it will hold if apply the 2nd.

imperialrc explanation is logical but let say the filtration is like filtering a sand with 1mm size filter, anything larger will not go through. Take the filtered sand (which is less than 1mm) and filter it again with the same filter will definitely pointless right? Same with light which is filtered by its wavelength. Well, I maybe wrong.

This post has been edited by sphiroth: Nov 3 2009, 06:57 PM

but ur example got some flaw..
sand is a thing with weight and shape etc while light/heat is a form of energy..
tint film limit/reject, not filter the heat..
im not sure but what i mean is if u flow 1 litre of water from a pipe, the x(can be anything) item will limit how much the water can go through the pipe while if "filter" means what substance in the water can go through and which cant such as condiments or minerals contained in water
juz my though

2 layers of tint will probably give you troubles for Smart Tag and GPS navigator.

b4 this i tot

of 100++ rejection...


@@

Its quite the same process actually. The heat is actually IR light ang light are categorized depending on its wavelength (and also frequency). By filtering certain wavelength, in this case IR, we are able to reduce heat going through the tint.

This post has been edited by sphiroth: Nov 3 2009, 09:00 PM

abg JPJ will smile if double tint... )

i double tint my car.
1st layer has about 80% of IRR rejection.
2nd layer has another 85% IRR rejection.

1st layer is titanium grey. 55% VLT. kindda shiny black. then it faded after a year.
so i weighted my options either to remove or apply another layer. a new layer would only fade (again) after a while.
so i applied another layer of black tint (not shiny) with 25% VLT. much lower than the law which states a minimum of 50% VLT. gonna take my chances with the JPJ.

at first it looks so darn black. can't even see anything inside even if you stare.
then, after more than a year it faded (again).

now closing to 2 years running on double tint, my car looks like your normal-newly-tinted-passing-JPJ-requirement and it doesn't fade anymore than it is. i park my car everyday under the scorching sun so fading is normal.
talked my way out of my first JPJ roadblock giving problem with my tint, and no more after that. JPJ now allows me to pass.

never had a problem with peeling, bubbling, tearing and GPS. i don't use SmartTag. but if GPS has no problem, i'm vouching that SmartTag would also pass.
make sure there's no problem with the 1st layer tint before you go and apply the 2nd layer. and the good thing about double layering is that even if the tint fades, the IRR stays the same. much less heat through the window now.

Not really, even my first tint doesn't look tinted, it's clear as day. The sales guy did scratch his head when I told him I didn't want it to look like tinted, that's why I'm opting for 2nd clear layer as well but with higher heat rejection percentage. Dunno if the rate is going to add up.

Some of the shops told me it's added up, some told me it adds up 5% extra, some told me, it's the higher percentage that counts.

I am confuse.

here's how to calculate, mathematically that is:-

you tint 65% heat rejection first and then on top of it another 82% tint. this means that sunlight passes through the 82% tint then only 65% tint.
light = 100% = 1
tint 1 = 82% = 0.82
tint 2 = 65% = 0.65

total heat after passing through 82% tint = 1 - 1x(0.82)
= 0.18

total heat after passing through 65% tint = 0.18 - 0.18x(0.65)
= 0.063

so in percentage, total heat that will go through both tints = 6.3%

if you tint 82% first and then on 65%, you'll get the same results.

but here's the catch, heat rejection rating is not equal to the visible light rating.....

you need to know what is the visible light rating/percentage for the tints because this is what JPJ uses to determine if you break the law. the law says visible light penetration through windscreen needs to be at least 75% if I recall correctly. if you know what is the visible light rating, you can use the same formula above to calculate the total visible light penetration.

but the problem is, car windscreen has its own filter value that sometimes causes not 100% visible light to go through even without tinting.

you will need to take this into account.

the best way to measure is to use the tool JPJ uses to measure the visible light penetration for your windsreen.

eg. if your tinting has 90% light penetration for 1st tint and another 90% light penetration for 2nd tint, and another 95% penetration for your own original windscreen, the total light penetration would be 76.95%.

hope this helps..........

Why should filtering starts at 82% since infra red wave will hit 65% layer first?

This is the order:

IR Heat---> Window---->65% Tint----->82% Tint.

Edit: Anyway, thanks for the input. Appreciate it.

This post has been edited by unknown warrior: Nov 6 2009, 08:39 AM

hi, sorry for bumping old topic.. i juz did my tint, quite clear maybe around 70-80% VLT.. planning to make it darker by putting another layer of black tint around 55-60% VLT on top of the exisiting tint.. any advice? thx

Performance Order Code VLT VLR UVR IRR TSER

Ray Barrier RB-01 63 9 99 95 60
Ray Barrier RB-SC 58 9 99 97 64

wrt the TSER double tint layer, based on your perception/calculation verdict,

37 celcius out door.

1st TSER = 1 - (37c x 60%) = 14.8c
2nd TSER = 1 - (14.8c x 64%) = 5.32c


Not quite practical with the figures derived from above calc.
as i still can feel the warm temperature on the leather seat spot where the sunlight lay onto.

This post has been edited by Mliven: Nov 19 2013, 12:52 PM