Rotary Strike Through Demonstration

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imported_Dave KG

New member
The paint on a car with a clearcoat is made of usually of two or three stages: primer, colour coat and lacquer. When polishing, either by hand or machine, we are abbradding away a very small layer of the lacquer/clear coat in order to remove the paint defects.



If you polish too far using to aggressive a compund, then it is possible to remove all of the lacquer coat and end up through to the colour coat - this is known as "striking through",and I'll demonstrate that here.



First of all, start with a three-stage painted panel - this has just been polished with Farecla G3 to an excellent finish:











Now, paint thickness readings were taken and revealed paint to be around 85 - 90um. This is very low thickness, and on a detail if you were to measure this thickness of paint then you wouldn't take any aggressive compounds to the paint... and this is why! I polishes the area by rotary polisher, Meguiars polishing pad and Farecla G3. One set of passes to thorighly break down the product, lift up the machine and here's the "yellow" pad:







This is a big indicator that you have struck through the clearcoat as you are no polishing colored paint and the pigment is dying the pad... Looking at the area polished now, we can see what a struck through area looks like:















 
Note that the area struck thorugh looks slighly lighter and lacks any of the gloss of the surrounding paint... This lack of gloss can be clearly seen under the Brinkmann light:



normal area:





struck through area:





half and half:





A check of the struck-through area reveladed a paint thickness consistently between 75 and 80um:











So... there we have it, strike through.



Clearly, if this was a genuine car and a genuine detail, if you measures paint thickness to be around 85 - 90um then you would rotary polish the paint with G3, as you would get strike through with the above... The moral of the story here being that if you are going to machine polish your car, its always much safer to check the paint thickness before using any abbrassive polishes, especially harsh compounds. :)
 
joyriiide1113 said:
Where can one get one of those gadgets?
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They are readily available on ebay - that particulalr model, direct from the manufacturer... I got mine however as part of a Group Buy on another detailing forum. Other companies manufacture them, there is the Elcometer for example, which may be easier to source in America...
 
Black240SX said:
How abrasive is the Farecla G3? In comparison to Megs polishes, for example.
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I would say its equivalent to Menzerna Intensive Polish - about 8/10 on the Meguiars scale I would say, but its hard to fully know...
 
its like your average white compound just below the aggresiveness of the ultra duty compounds that are usually brown/tan in color
 
Dave KG said:
They are readily available on ebay - that particulalr model, direct from the manufacturer... I got mine however as part of a Group Buy on another detailing forum. Other companies manufacture them, there is the Elcometer for example, which may be easier to source in America...
Click to expand...

Would anyone here on Autopia be willing to do a group buy ?
 
joe.p said:
Would anyone here on Autopia be willing to do a group buy ?
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I might be interested depending on the model and price. I already have an ETG1 for ferrous metals, so I'd only be interested in a model that measures on both ferrous and non ferrous materials as long as the accuracy is very good, the price is right, reputable brand, good warranty, etc.
 
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