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Thickness of wax layers?

84K views 96 replies 41 participants last post by  Sloafgb 
#1 · (Edited)
Does anyone know of any (scientific) measurements of the wax thickness put down in one or more applications? I have long suspected that the thickness is much less than one micron and am sorely tempted to make the measurements. I have access to equipment that can measure to less than one thousandth of a micron (a nanometre).
Of course it would be difficult to measure on a standard car panel so I will have to use something that is extremely smooth but too unlike a clear coat. I propose to use silicon wafers, which are the flattest, smoothest surfaces readily available. These always have a thin layer of oxide (silica in other words) on top, which we would usually measure as being 2-> 3 nm thick. Any objections to this, on the grounds of not providing a fair test, before I start?


NOTE (added 30th July) :- Results are shown in later threads
 
#3 · (Edited)
Great idea, the real benifit of this would be to see how many layers of wax you can put down before there is no increase in thickness with the addition of more layers.

Then comparing the layering ability of solvent heavy waxes and less solvent heavy waxes etc etc.....i'm sure we would be able to dream up no end of tests!!

I'm already preparing stickers for all my LSP's so i can write on the 'optimal/maximum' number of layers. :lol:
 
#4 ·
Great idea, the real benifit of this would be to see how many layers of wax you can put down before there is no increase in thickness with the addition of more layers.
And after it has been determined how many layers of carnauba wax can be applied before there is no increase, then the test needs to be repeated for a synthetic sealant.

I am really looking forward to the results!

Al
 
#5 ·
Go for it :thumb:

nobody has ever managed to measure any film build from layers of wax, properly applied, from what I have read....

I'd like to see your results. My only concern would be whether you can apply wax and buff it properly on this wafer you describe? It would be great to see what actually happens, and please use more than 1 wax, as their chemistry is so different that I suspect some waxes will layer and some wont (or it will be an almost negligible film build).
 
#6 ·
OOI - how would you calc depth? Paint reading first, then with a coat of wax, is any equipment capable of measuring accurately? What of two coats? Same surely applies, by whom and with what?

As it is applied in two ways (usually, unless I missed an alternative) by hand or applicator, whose hand, what size, how deep dibbing into CW?? Surely no such test would ever be worth the paper it was written on? IMO, and that is all it is, prepare the surface, end up with a coat of wax applied correctly, buffed, left or not, test to measure longevity. Then same again, two coats, and same test? Would ambient conditions be the same though, frequency of rain, road conditions??? Still not really conclusive is it?

A pro or highly experienced detailer could obtain result A on ABC car in ABC conditions, it does not mean to say I could come close unless I was able to duplicate the conditions therefore a 'hands-on' testing of such a product (IMO) is only ever likely to be slightly indicative, and a scientific test....? Well, again (IMO) about as much use as a one legged man in an ar5e kicking contest.

With respect.
 
#7 ·
Can the wax layer be measured? Yes.

How? Well, rather than me take up a lot of space here - just have a look at "ellipsometry" on wikipedia. This can measure the thickness (and the optical properties) of layers that have thicknesses of less than 1 nanometre, up to several microns. I use this and other optical methods.

Is it worth doing - I think so, and my colleagues would certainly believe the results. The method of application can obviously be varied to leave behind a well-defined layer, but the point of this test would be to see how much wax is left when applied in the "normal" way by cloths. I think I can do this part of detailing as well as anybody else, having looked after two cars for more years than I care to mention.

Is a silicon wafer the best surface to coat? Well it's the flattest, cleanest, smoothest thing you are ever likely to see. The wax won't actually "see" silicon because a silicon surface immediately forms a thin oxide layer on exposure to air. This grows to around several nanometres and pretty much stops unless heated. So chemically the wax will be adhering to silica.

I can also try coating the silicon with clearcoat, that slightly complicates analysis, but we measure lacquers and other coatings all the time and it is possible.
 
#9 ·
go for it and please document your process for the scientists here. I have always wondered by wax manufacturers have never published any findings on this topic? I know technology exists, so why have we never seen results? I suspect its because they wont be good (from a wax manufacturers point of view) and its in the interests of manufacturers to have us layer products and use more stuff :rolleyes:

Please use some quality waxes and some stuff that is regarded as very solvent heavy eg Colli waxes, FK1000 etc. I'd also love to see a water based spray wax product tested to see how that compares to paste products.

I'm looking forward to seeing your results :thumb:
 
#13 ·
Well, for a theoretical exercise, this sounds like a _lot_ of work. How many
here can even envisage what a micron is, let alone nano sizes? If we put this
into relative terms, using a measurement that we can envisage, then I still
wonder if the tests will mean very much to anyone other than a scientist.

Let's imagine (in relative terms) that one layer of FK1000p is one millimetre
thick and a second coat is only 1.5mm. With the first coat, there's probably
going to be some sort of chemical reaction with the paint. Applying the second
coat, is it safe to assume that a different chemical reaction may occur?
Could it be that the second reaction actually strengthens the first coat
protection as a result? Not by the thickness, but by the 2nd chemical reaction.

When you divide these relative measurements by 1000 or greater is it still
going to be possible to test whether or not there was any strengthening of
that first coat? If not, then all that work imo gives us figures that are
almost meaningless to other than a tiny minority of people. I guess that this
might partly answer BigPikle's question about why these figures aren't even
used by the most aggressive of marketing departments.

Having said all that, I'd be interested in seeing the figures if only to be
able to give an answer if such an arcane question came up in a pub quiz. :)

Regards,
Steve
 
#14 ·
I can also measure Gloss and the contact angle/surface energy if people are interested.
As far as waxes go, at the moment I only have Collinite Marque D'Elegance because that's what I use myself. If anyone wants particular products tested then I'm sure that I could spare a few more silicon wafers - maybe make it into a mini project for one of the PhD students!
 
#20 ·
1 nanometre = 10 Ångstrom
1 micron = 1000 nanometres

As the method described can potentially measure down to a few Ångstrom, I would expect it is the best chance of measuring the layers we are likely to get. Well worth doing as the OP has access to it - I imagine if you were to commission such work from a suitable organisation, it would cost more than we all spend on detailing :D
 
#16 ·
Hmm, it's interesting but I find it hard to agree that the time and effort taken is actually worth it. You say you're undertaking the test to find out how much wax is left after application but does it matter?

I'm not sure how other people here gauge their finish, but personally, if water is beading I don't wax, if it's not, I do. How does knowing the depth of my wax help me?
 
#18 ·
It would be great to measure precisely. We reckon wax coatings are no more than a micron judging from filling abilities etc, so potentially less. There are also tests we have conducted with particles of a known size (about 4 microns) which prove that the residual wax layer is less than this. But we don't know precisely, perhaps because our chemists have never felt it necessary to find out. But could well be sub micron, and would be great to maybe even see a wax layer under an electron microscope :) The Uni of Reading has potentially agreed to help us with some of these scientific research things, so we may do some more digging when we have time.
 
#24 ·
That's one of the interesting questions that we would then be able to look at.

Another thing is that I'm pretty sure that if you don't leave the wax area to dry and haze over (as the manufacturers recommend), but instead keep buffing with the original cloth, then you remove pretty much all of the layer you've just tried to apply.
 
#23 ·
These tests could perhaps resolve once and for all the question that has bedevilled all of us--namely, is it really possible to layer either carnauba waxes or synthetic sealants? If yes, how many coats may one apply until one reaches maximum, or is there a maximum? I am looking forward to the results!
 
#31 ·
Results!

Wax Thickness Test Results

Well here are some results of wax thickness as measured by reflectometry and ellipsometry.

The units given below are in nanometres, abbreviated as nm. For reference, 20 nm is 1/50th of a micron.
One micron is roughly 1/80th of the thickness of a human hair (hair thickness depends on hair colour/ethnic origin etc).

(Some technical details for the scientifically minded:- The methods used are capable of measuring to sub nanometre precision on clean silicon wafers.
However, the accuracy of the methods depend to some extent on the refractive index of the materials being measured.
Here we have used computer fitting to derive the thickness and refractive index dispersion simultaneously.
The value of refractive index obtained was 1.413 (at 632.8 nm) and the value quoted in the literature for pure Carnauba wax is 1.454 (wavelength not quoted).
This gives some confidence that the values of thickness are correct.
The clean silicon wafers were measured beforehand and thicknesses of 2 to 3 nanometres of silicon dioxide were shown to be present (as expected).
Silicon dioxide has a very similar refractive index to the wax and so cannot be distinguished from wax in the final analysis.)

The first tests reported below used Collinite no 915 applied to clean 6 inch diameter silicon wafers using a damp microfibre cloth (as manufacturer's recommendations).
Four silicon wafers were used, with slight variations on the waxing technique as given below.

Wafer 1. Wax was applied thinly with damp cloth, left for 5 minutes to haze over and then buffed off with clean microfibre cloth. No great effort was applied.
Measured Thickness = 22.7 nm (in centre of wafer)

Wafer 2. Wax was applied thickly with damp cloth, left for 15 minutes to haze over and then buffed off with clean microfibre cloth. This layer required a fair degree of effort to remove compared to wafer 1.
Measured Thickness = 20.6 nm (in centre of wafer)

Wafer 3. Wax was applied thinly with damp cloth, left for 15 minutes to haze over and then buffed off with clean microfibre cloth. No great effort was necessary.
Measured Thickness = 15.9 nm (in centre of wafer)

Wafer 4. Wax was applied thinly with damp cloth and buffing with clean microfibre started immediately.
= Measured Thickness = 16.9 nm (in centre of wafer).

The actual wax thicknesses will be 2 to 3 nm less because of the native oxide layer as explained above. (I do have the exact values)

One more thing before I finish for today. Our equipment can also measure the thickness distribution over the 6 inch wafer and a thickness map for wafer 4 is shown in the picture below.
Dark blue in the picture corresponds to thickest and light blue to thinnest.
In case it is not clear, the thinnest value was 15.05 nm and the thickest value was 20.26 nm (standard deviation is 1.25 nm and thickness uniformity is +-14.9%)

My first reactions are that I am surprised how little variation there is between wafers or over the surface of wafer 4. A standard deviation of 1.25 nm for a layer applied by a damp cloth is pretty impressive!
The actual thicknesses of 15 to 20 nm (or 12 to 17 nm minus the oxide layer) is not surprising because the wax layers look extremely smooth and there do not show any optical interference effects even on the ultra smooth silicon wafers
(like you see with oil on water or a soap bubble as it thins down to bursting). This in itself implies that the thicknesses are less than 100 nm.

Tomorrow I will try to add another layer to each wafer!
 

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#33 ·
Not sure how to interpret those results but the crunch for me will be tomorrows results. ie. Will a second layer of wax leave anything substantial to the thickness? I suspect that the result will be that it does add something, even if it's only in the realms of a more complete even coverage. This would be borne out by countless detailers that have commented that a finish looked glossier or deeper after a second coat. We will see what the test shows though. I look forward to hearing your summations.
A sealant test would be the next logical step I would imagine:thumb: Thanks for doing this test BTW:thumb:
 
#35 ·
After the second coat, we also need a third and fourth coat to see any further layers can truly be added. At some point we must reach a threshold when the paint surface can no longer hold more wax ... so one might think.

I am so glad this test is being done. And after the testing for the waxes is completely, please do an identical test on a synthetic sealant.

Thanks!
 
#36 ·
good stuff- thanks for posting

I would really like to see:

1. the 2nd layer measurement
2. the measurement of both layers if they were applied in the same session - perhaps 1 hr apart

This might give us some information about the effective difference (if any) of waitin 1 hr vs 24 hrs?

Thanks for taking the time to do this and provide more information to our debates :thumb:
 
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