# Safe to compound?



## Robin82 (Nov 19, 2018)

After buying a car thats a few years old I didnt want to head straight into compounding the paint with not knowing anything about the history of the car. So I thought the right thing to do was to buy a paint thickness gauge and measure the thickness of the paintwork of all the panels.

All panels bar the bonnet and near side wing measure between 220 - 300 microns. The bonnet measures between 110 at the front and 150 in the middle, similar with the wing. Which I assume means its been polished/had work previously.

Its a BMW Z4. Do I have much clear coat to play with on the bonnet? Would this area be safe to DA compound or would it be better to use an abrasive polish in this area? The compound I have is Megs DA Correction Compound (pink stuff).


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## Citromark (Oct 29, 2013)

The readings on the bonnet should be fine , I've just had readings done on my car by the kind bods at CYC while I was there and the readings down my drivers side were 80 , Dave at CYC said just to go careful and that readings of 60 and below would be a in dangerous territory. Just keep checking with your Ptg as you go if ypur worried .

Mark


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## Robin82 (Nov 19, 2018)

Thanks for your advice Mark, yes I think the bonnet will be fine. I've just been doing a little further reading and it seems taking readings from under the bonnet where there is no clear coat would give a pretty good estimate of how much clear coat remains. I got a steady reading of 50 microns from the under side and around the edge of the bonnet so I think this is quite conclusive. I have at minimum 60 Microns of clear coat to play with proving they applied the same amount of paint all over the car. (perhaps a little less on the none visible areas??)

I'd be interested to know how much clear coat is removed - on average - from compounding a car. I guess the amount of factors involved would mean its hard to define this.


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## Ultra (Feb 25, 2006)

The bonnet and nearside wing appear to be the only non repainted panels on the car, i'd be more concerned about the panels with high readings, without a guage that seperates layers you have no idea how thick or thin the clear coat is, without getting into nerding basically use the least aggresive product to get the job done and remember that perfection is not always possible.


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## chongo (Jun 7, 2014)

Ultra said:


> The bonnet and nearside wing appear to be the only non repainted panels on the car, i'd be more concerned about the panels with high readings, without a guage that seperates layers you have no idea how thick or thin the clear coat is, without getting into nerding basically use the least aggresive product to get the job done and remember that perfection is not always possible.


Was going to say this above^^^^

200-300 mc does indicate that they have had paint in the past look for any signs of any paint work (dust nibs, solvent pop, sanding marks are very good indication of a respray. As for the bonnet, I would still only use a medium polish as 110 is on the boarder line. You can still make a massive difference by just using medium polish and not compromising the clear coat:thumb:


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## Robin82 (Nov 19, 2018)

Yes the two differing readings do indicate something has occurred paint job wise. I’ve just rang the dealer and he advised he’d used a rotary polisher on a few areas which included the bonnet and the wing but I dont think that would account for the dramatic difference.

Do you think 200-300 is out of the ordinary for a fairly modern car (bmw 07)? It seems odd that all panels bar those front two would have been re-painted? They all look pretty soond bar the orange peel which pervades the entire car.

Thats sound advice on using a medium polish, the paintwork is in pretty good nick, no scratches or stone chips etc so probably wouldnt require a heavy cut anyway.


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## chongo (Jun 7, 2014)

What are you going to use for protection?


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## Robin82 (Nov 19, 2018)

chongo said:


> What are you going to use for protection?


Good question! I've just bought some Bilt Hamber apc and Shampoo so thought I'd try their Double speed wax as a fair few on here say its decent stuff and fairly durable. What do you recommend?


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## chongo (Jun 7, 2014)

Robin82 said:


> Good question! I've just bought some Bilt Hamber apc and Shampoo so thought I'd try their Double speed wax as a fair few on here say its decent stuff and fairly durable. What do you recommend?


Can't go wrong with DSW at this time of the year:thumb:


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## MBRuss (Apr 29, 2011)

Robin82 said:


> Yes the two differing readings do indicate something has occurred paint job wise. I've just rang the dealer and he advised he'd used a rotary polisher on a few areas which included the bonnet and the wing but I dont think that would account for the dramatic difference.
> 
> Do you think 200-300 is out of the ordinary for a fairly modern car (bmw 07)? It seems odd that all panels bar those front two would have been re-painted? They all look pretty soond bar the orange peel which pervades the entire car.
> 
> Thats sound advice on using a medium polish, the paintwork is in pretty good nick, no scratches or stone chips etc so probably wouldnt require a heavy cut anyway.


Yes, 200 - 300 microns is fairly thick, and if it was the normal thickness of the paint then the dealer would have cut 2/3rds of the paint off the bonnet and wing, which would suggest there is no more paint left to remove on those panels.

I'd concur with others in saying that the 200 - 300 micron areas have been repainted. That's a lot of paint.

My 2016 BMW reads around 130 - 150 microns, from memory. My old VW was in the same region as that also.

Check inside the door shuts and see what they read.

Sent from my LYA-L09 using Tapatalk


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## Robin82 (Nov 19, 2018)

MBRuss said:


> Yes, 200 - 300 microns is fairly thick, and if it was the normal thickness of the paint then the dealer would have cut 2/3rds of the paint off the bonnet and wing, which would suggest there is no more paint left to remove on those panels.
> 
> I'd concur with others in saying that the 200 - 300 micron areas have been repainted. That's a lot of paint.
> 
> ...


Yes I agree, and to be honest thinking about it objectively the paintwork is a little too good (in terms of scratches/stone chips) for the age of the car (07).

So I guess the most likely reason for the difference in paint thickness would be that the 2 front panels had taken a little damage and needed to be replaced so the owner at the time decided on a full re-spray. It's the only logical explanation I can think of.

I'll check the inside of the doors.


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