# Strike through:(



## M.J (Mar 17, 2010)

Well today i messed up very badly on a rather nice 1996 audi S2 i,m polishing . Its the first time i,ve damaged a car since machine polishing , I,ve done around 10 cars only so i,m still on a massive learning curve but today just freaked me out and it just came with a click of a finger . Luckily the owner paints cars for a living so it would of been a dam sight worse situation . Very lucky indeed in a way . 
Having sat back and thought on what happened i know where i went wrong but boy what a nightmare . I,ve been a little tired lately with lack of 100% concentration mixed in with complacency i have learned the hard way . The n/s rear arch was the culprit , i was polishing the curve of the arch and the surrounding area above it,It seems like the outer part of the pad being dry damaged the arch via heat by the looks of things , then literally chopped its way several times ( 1 inch area) in an instant . Horrific indeed 

Until it happens to you,you realise how serious what your doing is and the possible dangers . Personally i,m absolutely gutted that i did it but i hope i can learn from my mistakes and become better from it. I certainly have more respect for machine polishing than i already did and have changed my methods and approach instantly. 
Nobody is perfect i guess but i cant be doing this again , anyone else had drama,s to this effect ? Shakes you up doesn,t it lol!!! 

sorry for long post , thanks for reading 

Mike


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## ginge7289 (Feb 21, 2011)

I am guessing you were using a rotary? Was it OEM paint or had it had a respray?


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## Rust.Bucket (Feb 11, 2011)

Has it made you start thinking about a ptg more now?
Hope it hasn't put you off picking up a machine again!


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## M.J (Mar 17, 2010)

The owner has painted the car twice actually , once a full respray , the second time the sides were done. I have been using my ptg and the readings are healthy . I think i had to much speed in a small area for too long, the the edge of the pad has hit it. Also i should of used the 80mm spot pad for this . Kinda lazy i think !

The next hour i was extremely nervous with the rotary , but have knuckled down and carried on . With my new methods lol


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## ginge7289 (Feb 21, 2011)

I had strike through using a DA, on the wife's car, so I am guessing the paint is very thin. Did not use a DTG, but can clearly see that it had a real poor paint job. You will learn more from this and be better for it.


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## james walker (Apr 18, 2010)

anything to do with the anmount of resprays its had done? seems too easy to strike through from what youve descirbed.


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## Posambique (Oct 20, 2010)

Thank you for posting the thruth and being honest with it.

I'll surely be even more cautious the first time I'll try machine polishing.


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## M.J (Mar 17, 2010)

Please do not get put off of machine polishing , i made a careless mistake on speed 2.5 for too long and i managed to touch the arch with a dry edge . The paint isn,t thin. I just felt being honest and open about it . I,m not finished by a long way and will continue , maybe i,ve been too honest i dont know haha .


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## Planet Man (Apr 12, 2008)

Gutsy post Mike. Had a nightmare with a rotary many years ago when I was in the bodyshop game. I'm a DA man now, but one day I would like to have a go with a rotary again to lay the demon to rest


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## M.J (Mar 17, 2010)

Gutsy maybe , i dunno but i dont mind being honest , part of me feels i should be for some reason , i,m really getting into polishing now and have made a mistake , a big one granted but we are human after all. Obviously one of the worst things that can happen has done .Being as Kev the owner has been more than brilliant about it and he can fix it has of course put me at ease hence i,m lucky so should at least own up pmsl. I,ve posted a few decent results before on here , not this time but as said, i,m not giving up on it just yet , life doesn,t always go our way i guess

Planet man get the rotary out again you,ll love it


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## Jacktdi (Oct 21, 2010)

Don't let it knock you back.

Happened to me when I first started machine polishing around 2 years ago on a 206, my bloody heart sank when it happened, horrible feeling.


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## M.J (Mar 17, 2010)

I,m gonna try my best not to , thanks , yes i felt that sinking feeling today i felt i had the courage to carry on


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## HeavenlyDetail (Sep 22, 2006)

This isnt strike through , thats when you slowly work a thickness down till there is none left and you enter the next layer , this is burn through from friction and heat as you state an almost ripping of the paintwork in an instance , they are two massively different things..
Using a Ptg would have made no difference on burn through compared to strike through.


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## Dream Machines (Mar 13, 2006)

Yes. There are two types of paint burn that I know of

Pad Burn - pad dries up and becomes more like an angle grinding disc and digs into/gouges the paint.

Delamination - too much friction/heat causes the clear coat to separate from the colour coats (clear bubbles)
This happens alot on rear quarter and front fenders about 1 inch from the bottom of the fender where the crease line is. paint there doesnt like it if you do high speed vertical passes. Keep it horizontal 

Honestly I've used Xpert and S1 at up to speed 4 1/2 and not had a problem
though black baron is used always and im moving the machine much quicker
med to high heat aint bad for paint but heaps of heat isnt either


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## HeavenlyDetail (Sep 22, 2006)

This is why heat and lack of lubrication are such killers and everyone is always worried about depth , if you think about most paintworks being 80/90 microns+ yet we only remove 1,2 or 3 microns it shows that striking through is generally edges and corners etc , burn through on the other hand is very easy to do and i would say is the cause of 90% of all accidents. Its a learning curve for everyone which is why i spent so many hours destructing panels rather than correcting when i started learning machining, if you,ve never struck or burnt through paintwork you never know how far away from it you actually are or how easy it is to do.


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## Rust.Bucket (Feb 11, 2011)

So what does 'burn through' look like as opposed to strike through? And I'm guessing it can be rectified (more easily and cheaply)?


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## Dream Machines (Mar 13, 2006)

that is so true heavenly. 
I'm finding that black finishing pads are one of the most dangerous for pad burn


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## MAUI (Feb 1, 2008)

Dream Machines said:


> that is so true heavenly.
> I'm finding that black finishing pads are one of the most dangerous for pad burn


Why is that? I would think a more aggressive pad like the LC yellow would burn paint quicker than a soft black pad.


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## Chicane (Mar 31, 2011)

i found this vid quite interesting, nearly an hour long though 






(sorry, tried to embed vid but failed)


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## R0B (Aug 27, 2010)

Dont let it destroy your confidence,learn from it and move on sir


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## TOGWT (Oct 26, 2005)

MAUI said:


> Why is that? I would think a more aggressive pad like the LC yellow would burn paint quicker than a soft black pad.


There are too many variables for paint burn to specific to a to abrasive level (colour) of a pad (speed, friction (kinetic energy), applied pressure, foam pad actual surface contact area, pad and polish / compound grit number (abrasive ability) amount of surface lubrication available, area being polished, and material (paint, plastic, metal, etc) heat conductivity).

Paint Burn is caused by a lack of surface lubrication (dry pad) and kinetic energy (friction) causing the pad to becomes more like a sanding disc, which produces excess surface heat, consequently the paint reaches its melting point.

Given the right circumstances this can happen with either an orbital or rotary machine polisher


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## PaulN (Jan 17, 2008)

Reading between the lines was the machine more at and angle as the pad was too big therefore heating the edge fast and becoming too aggressive?

Very interesting reading about drying out as i do find the rotary drys out polishes so much fast that the da.

Thanks for posting this.

PaulN


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## Beancounter (Aug 31, 2006)

Rust.Bucket said:


> So what does 'burn through' look like as opposed to strike through? And I'm guessing it can be rectified (more easily and cheaply)?


See a good guide from Dave KG here :thumb: (looks like the term burn/strike through is sometimes interchanged)


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## Martin_HDI (Aug 19, 2010)

Dream Machines said:


> that is so true heavenly.
> I'm finding that black finishing pads are one of the most dangerous for pad burn


I was using a black finishing spot pad on a DA and managed it, I was gutted cause I didn't think I even touched that area yet with the DA but must have been an edge.

It's gutting but it's only paint :thumb:


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## Chufster (Nov 21, 2010)

Well done for admitting it. Everybody makes mistakes and It'll help others learn from your experiences. :thumb:


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## twissler (Apr 6, 2009)

Whats the bestway to avoid this then? I exclusively use a DA so i'm at less risk but reading a few comments on here about accidents using a DA has made me sit up and take note.

Would too little product on the pad contribute to pad heat? What about hot panels when polishing in sunlight?


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## TOGWT (Oct 26, 2005)

twissler said:


> Whats the bestway to avoid this then? I exclusively use a DA so i'm at less risk but reading a few comments on here about accidents using a DA has made me sit up and take note.
> 
> Would too little product on the pad contribute to pad heat? What about hot panels when polishing in sunlight?


'Spot' heating is the problem, UV heat spreads the heat over the surface


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## twissler (Apr 6, 2009)

TOGWT said:


> 'Spot' heating is the problem, UV heat spreads the heat over the surface


What about the amount of product on the pad?


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## james_death (Aug 9, 2010)

Great post and goes to show that mistakes are easy to make even when having a few under the belt, very honest of you.

Talking of resprays im now convinced the rover has had a relacquer as notice the lacquer peeling along chrome trims and the RDS under the lacquer confirms it...:lol:


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## M.J (Mar 17, 2010)

PaulN said:


> Reading between the lines was the machine more at and angle as the pad was too big therefore heating the edge fast and becoming too aggressive?
> 
> Very interesting reading about drying out as i do find the rotary drys out polishes so much fast that the da.
> 
> ...


This is exactly what happened pal sorry for not being more clear i couldnt of put it better. The outside edge on an angle, the pad being dry is whats caused it alongside too faster speed for too long .

Thanks for all the comments its made me feel a little more human , i have now started to prime and apply polish to edges of pads where needed and take an even more careful approach and a lower top speed .
James_death and chufster thanks again guys 

Mike


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## HeavenlyDetail (Sep 22, 2006)

M.J said:


> This is exactly what happened pal sorry for not being more clear i couldnt of put it better. The outside edge on an angle, the pad being dry is whats caused it alongside too faster speed for too long .
> 
> Thanks for all the comments its made me feel a little more human , i have now started to prime and apply polish to edges of pads where needed and take an even more careful approach and a lower top speed .
> James_death and chufster thanks again guys
> ...


Mike thanks for posting what many would call a taboo thread, it's good for threads like this to surface because it's the side rarely seen, all the shiny cars and dimly reflective pictures hiding what in reality is a subject that needs to be shown more, hopefully people get better understanding from threads like this and due to that take more precautions and realise that even some state it's relatively impossible to burn/strike through you alone have proven it isn't.


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## eddiel34 (Mar 22, 2008)

You learn more from one defeat than you do from ten victories.


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## M.J (Mar 17, 2010)

Heavenly said:


> Mike thanks for posting what many would call a taboo thread, it's good for threads like this to surface because it's the side rarely seen, all the shiny cars and dimly reflective pictures hiding what in reality is a subject that needs to be shown more, hopefully people get better understanding from threads like this and due to that take more precautions and realise that even some state it's relatively impossible to burn/strike through you alone have proven it isn't.


Thanks for the kind words Heavenly it means a fair bit actually and i do hope it can help others if thats possible. Yes taboo i understand in a way but surely we dont just want all the glory especially on such a good spot at DW. There is everyone on here skill wise , some may be cringing i,m sure and thats fine , my experience so far comes from alot on here and have a huge respect for that.

Eddiel34 you,ve summed that up quite nicely , very very true


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## Dream Machines (Mar 13, 2006)

MAUI said:


> Why is that? I would think a more aggressive pad like the LC yellow would burn paint quicker than a soft black pad.


some black pads have a funny (sort of squeaky feel to them and sometimes when they dry up, you can hear them squeak on the panel (rotary that is)

I've had a black pad cause pad burn (leaves semi circular or level slices into the paint that you can feel with your fingernail) at 900 rpm with my makita rotary and menz 85rd)
luckily it was a test panel

Polishes and crap clear coats could be a factor in this too. the lubrication of menz 85RD (waxy oil) in particular means your more prone to pad burn with that than what I am now using. 
we found 85RD and other products we were using prior, to make the rotary not glide over the surface that well. with what we use now, it glides over the paint real easy

crap paints can be sticky (low abrasive resistance I think) and a certain technique must be used otherwise burn has a bigger chance of occuring) 
LC yellow pads are a problem. thus why I dont use them. they must of changed the foam formulation when they went from eurotech to ccs (the eurotech yellow was smooth, the ccs is like sandpaper)

megs burgundy is a no go zone for me. hate them with a passion.


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## MAUI (Feb 1, 2008)

Dream Machines said:


> some black pads have a funny (sort of squeaky feel to them and sometimes when they dry up, you can hear them squeak on the panel (rotary that is)
> 
> I've had a black pad cause pad burn (leaves semi circular or level slices into the paint that you can feel with your fingernail) at 900 rpm with my makita rotary and menz 85rd)
> luckily it was a test panel
> ...


Thanks for the reply. I've been using 85rd with a black LC pad and a black 3M pad with 85rd @ 1800 rpm with no problems. Maybe just lucky.


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## TOGWT (Oct 26, 2005)

Kudos to OP for posting so we can all learn from the mistkes made.

I'll post the whole sub-section for future reference-

*Strikethrough* (Paint Burn)

Strikethrough and Paint burn have very similar cause and effect and these terms are often used interchangeably. It takes longer to strikethrough paint in the middle of a panel as opposed to an edge. Basically when kinetic energy (friction heat) has compromised the clear coat and exposed the base coat. Paint often looks a slightly lighter colour; it's usually concentrated on a small area or 'spot 'You will also be able to see a non-glossy patch (base coat) where the clear has been removed with the edges of the remaining clear coat being visible .

Speed, friction (kinetic energy), applied pressure, foam pad actual surface contact area, pad and polish / compound grit number (abrasive ability) amount of surface lubrication available, area being polished, and material (paint, plastic, metal, etc) heat conductivity. Given the right circumstances this can happen with either an orbital or rotary machine polisher

Applying pressure and holding the polisher stationary in one area for too long will cause friction heat to be concentrated on a small area, especially with a foam pad due to their high surface resistance (friction heat) although a wool pad has a much lower surface resistance they are more abrasive.

*Paint Burn *(Strikethrough)

Paint burn and Strikethrough have very similar cause and effect and these terms are often used interchangeably. Although it is usually a combination of things, the most common cause of paint burn is a lack of surface lubrication (dry pad) and kinetic energy (friction) causing the pad to becomes more like a sanding disc, which produces excess surface heat, consequently the paint reaches its melting point

•	Speed - using too high a speed will not necessarily get the job done faster as there is a risk of instilling swirl marks or strikethrough, which will need to be corrected to remove

•	Pressure - excessive pressure will make the pad / polish combination more aggressive, this has the effect of increasing kinetic energy (friction heat) which may result in a strikethrough, a friction paint burn or paint delamination from the substrate. Increased surface friction will also cause swirl marks

•	Heat - excessive heat and a combination of excessive pressure (surface resistance) speed and an aggressive pad / polish combination will rapidly generate surface heat, this will soften the paint and may cause delamination from the substrate, surface hazing, strikethrough and greatly increase the chance of swirls.

•	Pad angle - relative to the paint surface ideally the pad should be operated flat to the surface; this provides the correct contact surface area along with sufficient surface lubrication from the polish oils. By turning a pad on an angle you reduce the surface area contact, increasing pressure and kinetic energy (heat) while, reducing the amount of surface lubrication available.

•	Insufficient product - without the polish lubrication oils, dry buffing will cause delamination from the substrate, surface hazing, strikethrough and greatly increase the chance of swirls.

The clear coat provides both ultra violet (UV) radiation and the paint systems protection. Repair any breaches in the clear coat system otherwise you risk the paint drying out and delaminating, which will then require repainting

*Areas of higher risk*

_Bumpers -_ often made of a composite material, they don't conduct heat like metal panels, the paint in these areas, especially edges are generally thin (masking tape is good insurance)

_Panel edges and seams-_ when approaching an edge always make sure the pad backing plate is spinning from the panel toward the edge and not coming from the outside to the edge where it can catch the edge and strikethrough.

{Knowledge Management} - Treating experience as a shared asset. If this article was informative and you learned something new, or have any questions feel free to comment. We would love if you shared this article with your friends on Facebook and Twitter or linked to it from your website or blog- Thanks

Also see my Blog for constantly updated detailing info  TOGWT ®Blog


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## M.J (Mar 17, 2010)

TOGWT brilliant post mate , thanks for puting this ^ up . 
I cant seem to get your link to work . 

Mike


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## Dream Machines (Mar 13, 2006)

MAUI said:


> Thanks for the reply. I've been using 85rd with a black LC pad and a black 3M pad with 85rd @ 1800 rpm with no problems. Maybe just lucky.


nah not luck. most likely working with excellent paint thats not as sticky or grabby
though theres no need to use 1800 rpm with 85RD. once the one correction step has been done, the following products to polish, finish and jewel dont need to be run at that speed.

900 to 1300 is great, a little higher with much faster movements to glass out the paint with 85rd. 
as long as you slow back down your revs with 85rd, theres no probs using 1800.


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## The Detail Doctor (Feb 22, 2008)

Did you have insurance?


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## Mirror Finish Details (Aug 21, 2008)

3M black pad is a strange one compared to the blue one.

I only ever use it with a glaze that is very oily an donly ever take the machine to about 1200rpm with it.


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## TOGWT (Oct 26, 2005)

M.J said:


> TOGWT brilliant post mate , thanks for puting this ^ up .
> I cant seem to get your link to work .
> 
> Mike


  TOGWT ®Blog


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## MAUI (Feb 1, 2008)

TOGWT said:


> TOGWT ®Blog


Doesn't work for me.


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## M.J (Mar 17, 2010)

yep still not for me


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## HeavenlyDetail (Sep 22, 2006)

http://togwt1980.blogspot.com/


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## DanSN117 (May 5, 2007)

Happens to everyone, i struck through on a mini about a month back. Was wetsanding a key scratch the length of the car. It didnt occur to me that the fuel cap would have different levels of paint on it. This was until the silver paint turned white.

Hmmph.


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## TOGWT (Oct 26, 2005)

Heavenly said:


> http://togwt1980.blogspot.com/


Thanks...where's my 12 year old computer expert when you need her?


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