# Problem with polishing a bonnet



## j1ggy (Feb 17, 2012)

So, I have this mate who owns an mk1 Ford Probe, who came to me for a polishing job about a year ago, and on the bonnet I have taped of a section for a 50 | 50 shot. Polished it all flat afterwards. No marks or anything similar visible.
After a couple months he called to tell me that the "line" was clearly visible. So he drove it for me to see, and clear as day, it was very visible.
I polished the whole bonnet with Scholl S17+ and S40 afterwards. But as soon as I sprayed Last Touch, Zaino Z-8 or any fluid at all on it, it would leave marks and marring from MF. And all I could do is repolish for it to disappear.
Its a single stage black color.
Now, after 4 months, he calls me to say that it has reappeared (the line where the tape was). And I'm all out of ideas...
Mind you, he doesnt have a bonnet liner underneath it and as the engine is really close to it, its get fairly hot and doesnt cool down for a fair amount of time after the engine is shut down. I poured a fair amount of water over it for it to cool down, but after a few minutes it gets warm from the engine heat, although the engine itself wasn't running for at least half an hour.
Need some pointers...
I am using a FLEX rotary (L3403 VRG).


----------



## AllenF (Aug 20, 2012)

You cant so anything if the panel is more than barely warm so you would need to get the car and give it a few hours to cool NATURALLY . Then redo the whole bonnet you will need to strip it right back and remove EVERYTHING previously on there and refine it HARD then hand polish it
The next option would be to wetsand the line out but it may just be residue that has been polished over somehow .


----------



## j1ggy (Feb 17, 2012)

Ok. I havent been 100 percent clear on this one. Its not the line of the tape thats visible (3M 3434 was used), but rather the whole side of the bonnet.

Here's an actual photo when the bonnet was worked on for the first time:









It was polished to en even finish at the time. And it fades to this after a few months... I'm still puzzled as to why Z-8 or LT leave marks on it (either side of it), but not on any other car I've worked on.

As a reference, this is how it looked as a finished product after the first polishing session.


----------



## BoostJunky86 (Oct 25, 2012)

So one whole side of the bonnet has gone full again?


----------



## AllenF (Aug 20, 2012)

Mmmm depth readings from all over bonnet.
Sounds like you have gone too hard on one side and its now blooming . 
But that wouldnt make sense.. Why would you go harder on the second side???
Need readings to determine whether its had a previous paint job that you have removed somehow. It looks in the first pic like a sh1te attempt at wetsanding?
Get the readings then strip the whole bonnet back and give it another go if you have enough to work with then seal it when its done. Do it when its cool naturally not a forced cool down (never a good idea on paintwork)


----------



## j1ggy (Feb 17, 2012)

Yup. The whole side has gone back to that dull, washed up look.
And I still don't get it as to why any other part of the car hasn't gone the same way as it has been treated in the same way all round.
Sanding paper and this car haven't been in the same room.
I will have to take depth readings and continue from there.
But as it sits right now, my best bet would be to go with a wool pad or spider pad + Scholl S3 and then refine. Or, if its really bad, P2000 and then take from there...

Now, when I come to think of it, I remember when back in the day I used to take scrapped bonnets and doors to practice on. And if I used wool pad and heavy compound on one side and just a foam pad and medium compound on the other, it would look the same, but it would show the difference after some time. I never used a tape as a divider, but I think its the same thing a got here. 
Although in this particular case I have used the same combination on the whole bonnet. I think I'm on to something here...


----------



## BoostJunky86 (Oct 25, 2012)

AllenF said:


> Mmmm depth readings from all over bonnet.
> Sounds like you have gone too hard on one side and its now blooming .
> But that wouldnt make sense.. Why would you go harder on the second side???
> Need readings to determine whether its had a previous paint job that you have removed somehow. It looks in the first pic like a sh1te attempt at wetsanding?
> Get the readings then strip the whole bonnet back and give it another go if you have enough to work with then seal it when its done. Do it when its cool naturally not a forced cool down (never a good idea on paintwork)


Allen. If it was a previous paint job etc why would it have come back in the same perfect line as the tape, would it not come back and reflect where the previous paint job was at all(assuming that's the reason and its not because its been worked to hard and the lawyers now to thin and bloomed) not questioning your knowledge asking to learn .


----------



## BoostJunky86 (Oct 25, 2012)

Got a pic of how it looks now at all buddy? 

As said maybe you've removed a not to much but again you may not have done enough and the protections worn off showing the paint finish required further 'finesse' applying. Either way hope its figured out and you solve it soon far beyond my skill level I think sorry I was no more help


----------



## AllenF (Aug 20, 2012)

Go with the spider pad AFTER making sure you got enough to safely play with.
Wetsanded properly should remove less but its gonna be a pita to do the whole bonnet.
Just seems wierd that its upto your tapeline.
Im inclined to say it is something you have done. but i dont want to as cant be certain as i havent seen it.
QUESTIONS
When you redid it did you retape along the same area??? 
Did you redo the whole bonnet???
Did you start on the same side as when you first did it??
Is it using EXACTLY the same technique over the whole bonnet. All done in one sitting. ( you didnt do half then work round car and end on other side)??
The only other thing i can think of would be that the paint has somehow objected to being force cooled ( if you did when you first did it)


----------



## j1ggy (Feb 17, 2012)

BoostJunky86 said:


> Allen. If it was a previous paint job etc why would it have come back in the same perfect line as the tape, would it not come back and reflect where the previous paint job was at all(assuming that's the reason and its not because its been worked to hard and the lawyers now to thin and bloomed) not questioning your knowledge asking to learn .


If it was worked on to hard, that would have to be the right side of the picture as you're looking at it, as it was worked on first.


----------



## BoostJunky86 (Oct 25, 2012)

So out if the two you'd say you worked the right side harder than the left?


----------



## AllenF (Aug 20, 2012)

BoostJunky86 said:


> Allen. If it was a previous paint job etc why would it have come back in the same perfect line as the tape, would it not come back and reflect where the previous paint job was at all(assuming that's the reason and its not because its been worked to hard and the lawyers now to thin and bloomed) not questioning your knowledge asking to learn .


No i see your point boost.
If the whole bonnet has had a blowover. Been taped then worked hard to remove defects on right thus cutting through the blow job and flatting process and then the left side has been lightly done ( due to pad/product selection determined to be correct as per test on right hand side) then it would only show to the original polishing tapelines.
A depth reading should be able to prove or disprove this theory though ( need about ten per side in the same places on each side)
So in theory if correct right side has been corrected fully to original paint LEFT side has been thinned so as to show the flatting marks. The oils in the polish will shine it out until they wear out then show back


----------



## j1ggy (Feb 17, 2012)

AllenF said:


> Go with the spider pad AFTER making sure you got enough to safely play with.
> Wetsanded properly should remove less but its gonna be a pita to do the whole bonnet.
> Just seems wierd that its upto your tapeline.
> Im inclined to say it is something you have done. but i dont want to as cant be certain as i havent seen it.
> ...


I know its something that I've done. Just can't get my head around as to what exactly.
I did redo the whole bonnet, and just the bonnet.
No tape was used.
It was divided into 6 sections and worked on accordingly with no pauses.
It was not force cooled the first time, and was not force cooled after the first pass on the second take. Then it was cooled but it was barely warm (it gets warmer while polishing then it was before I poured water on it).

I'll paste this here:
Now, when I come to think of it, I remember when back in the day I used to take scrapped bonnets and doors to practice on. And if I used wool pad and heavy compound on one side and just a foam pad and medium compound on the other, it would look the same, but it would show the difference after some time. I never used a tape as a divider, but I think its the same thing a got here. 
Although in this particular case I have used the same combination on the whole bonnet. I think I'm on to something here...


----------



## BoostJunky86 (Oct 25, 2012)

So dependant on depth readings. It could just be a case of another hour or so's work to polish the left side to its required shine again


----------



## AllenF (Aug 20, 2012)

Yup boost basically
J1ggy YOU may have used the same process on both sides
BUT and its a big but has someone else done what you have described. 
If you divided the bonnet into 6 then it MUST be before you done it.
You cant get the same defect over THREE work areas with that sort of consistency ( unless you are lucky or rather unlucky)


----------



## j1ggy (Feb 17, 2012)

(I'm typing as I recall the process)
Hmmmm, I started working on the car from the bonnet and that was my test section. I taped it off as a showcase. Keep in mind that this was done the first time.
Maybe I used a tad more pressure / speed / passes on that side (right) and when I found my combination, I used that on the left, but all it did was remove some of the oxidation, but not all of it. I just overlapped over the tape a bit to get it not to show, but if I had worked to hard to it on the right side, it would still reappear. At the time, I used 3M Extra Fine + and Megs Polishing pad (yellow). I would finish with Menz 85... Wolf's Body Wrap was used as LSP.
Basically, I screwed up that one and need to make amends. Wool pad and S3 should take it where it should be. Then its easy. I just F'ing hate wool pad...


----------



## AllenF (Aug 20, 2012)

K get the depth readings and you will probably find a few microns difference .
Strip the whole bonnet back redo it from scratch using LESS pressure / passes on the RIGHT.
Just reverse what you first did more pressure / speed / passes on the left.
Then seal the whole bonnet in one go.


----------



## j1ggy (Feb 17, 2012)

Forgot to say thank you, to you both!

Will do the car in next few days and post my findings here.


----------



## AllenF (Aug 20, 2012)

No worries.
Its hard to say its something you have done.
Reading throu then putting all the bits together somehow alarm bells arnt ringing. ( unlike those that burn through with a da on a bmw LMFBO)
You seem fairly competent on a machine which tends me into thinking it was an underlying problem that you have uncovered.
Its nothing provided the depth is there that cant be fixed somehow.


----------



## j1ggy (Feb 17, 2012)

As it is single stage, it will be fairly easy to work on, but still...
Depth gauge and a piece of paper will tell... But I recall it had a fair amount on it to play with.


----------



## BoostJunky86 (Oct 25, 2012)

Sounds like its time to give it another shot ;?


----------



## AllenF (Aug 20, 2012)

Yup but do try and level the readings up if left is different to right. If you can


----------



## j1ggy (Feb 17, 2012)

Update.

The matter has been resolved. It (dullness) wasn't really visible. But still I decided to tackle it and keep my reputation untarnished. 
As it appears the freakin' 3M EF+ contains some sort of oils, as I discovered a little while ago. And no matter that I used IPA, it still left some glossiness to the finish. That's one of the main reason I substituted it with Scholl range and never looked back.
So, the depth of the bonnet was around 125um all round and not much could have been seen from the readings, as the difference was faint. So I tackled the whole bonnet with 3M wool pad + Scholl S3 with a little more pressure applied to the left side, to even the things out. I refined from that and finished with Menz 85RD. It was glossy enough, but than I went for the Megs M7 and that really brought the POP out of that finish. Sealed with Megs M21 and then Zaino Z-8.
The owner was blown away by the finish.
I could have applied a better LSP, but this combination is pretty good.


----------



## AllenF (Aug 20, 2012)

So it wasnt really your all your fault.
Partly your fault for not doing the whole panel in the same product but also product has to share the blame too.
Glad to see you got it sorted
125Um you got probably 2 morereally big hits on that.
Allen


----------



## j1ggy (Feb 17, 2012)

Yeah. But its more of an enhancement job from now on, rather then a correction. So I it has a lot more to go. 
But its hard to explain to people that a better LSP gives you more time between polishing session and that you have to leave a certain thickness of the paint on it...


----------



## caledonia (Sep 13, 2008)

Glad to hear you have the issues resolved as a whole. And I do agree with your comments regarding ExtraFine. Noticed this myself it. It has a bad habit od masking and everyone should be aware of this. But then again so does S3. It has not got the nickname in the states as being the filler from Manila for nothing. Quite often you will notice quite a bit of fall back from this compound it you do not take steps to verify your correction.
Only concern I personally have is the use of 86rd to remove the marring from the wool as generally this would not have significantly enough cut to remove this.. Did you verify the finish with a wipe down prior to M7??
Just to safe guard any further blooming in the future with possible wool marring being the cause, or did you carry out a further stage that was not mentioned. 
Gordon.


----------



## Dave KG (Feb 23, 2006)

AllenF said:


> So it wasnt really your all your fault.
> Partly your fault for not doing the whole panel in the same product but also product has to share the blame too.
> Glad to see you got it sorted
> 125Um you got probably 2 morereally big hits on that.
> Allen


I'm not sure I would say the product is to blame per se... a lot of polishes contain oil or waxes as part of the lubrication process for one, they are not there as dedicated fillers but they can have a masking effect that any end user should be aware of. This is where set length and fully working a polish really does become vital - short setting will mean the abrasive leaves marring that these oils can then mask, where as working the polish fully and correctly will ensure that the abrasives are fully worked and dont leave any marring that the oils can then mask. It comes down to ensuring the product is correctly used, and that the job is not rushed - if machine finishing is rushed, then you leave yourself open to inadvertent masking. Perhaps why a car can look a million dollars when machined quickly, but this finish doesn't last like a finish which is machine *properly*.


----------



## AllenF (Aug 20, 2012)

This isnt marring though this is bloom from the oils in the 3m not being fully compatable.
So i would say yes the product is slightly to blame ( whether the compound OR the lsp) for not being universally compatable like the scholl stuff or menz stuff or even the megs stuff is.
There are a couple of products out there that spring to mind that dont like other products. Years of experience tells you not to mix them but it can (as you know dave) be very easy to overlook. Especially when its on a test section


----------



## j1ggy (Feb 17, 2012)

@ Gordon

S3's filling capabilities don't bother me, as I never used it without it being followed up by a less abrasive compound. And IPA wipedown should take care of any oils, fillers etc. that are in the compound.
In this particular case (or any other) I always follow S3 up with S17+ and then go for further refining if necessary, depending on the paint color.

@ Dave

Yup. As this was the test section on a car and paint that I have not have a pleasure of dealing before, I tried a few combinations of pads + compounds and there is a high possibility that I have left some of the product on the paint unintentionally before settling for a combination.
But it still doesn't explain the fact that the dullness came back and that both sides were affected to a certain degree even after the second time we tried eliminating the imperfections.
I contribute that to a lack of under bonnet lining, engines proximity to it, a really big engine in relation to its displacement of just 2.2 litres and a fact that when the car arrived at temperatures near freezing yesterday you could actually hear the engine oil cooking in the engine itself, even 10 minutes after the engine was shut off. And it stayed warm for two hours more. Even after that time you could put your hand 10 inches above it and feel the heat.
And the owner explained he has made mods to the ECU, turbo and added boost control unit which bring the performance, and therefore the engine to its limit and raise temperature of the whole unit, inevitably.


----------



## AllenF (Aug 20, 2012)

As i said earlier product is at fault too slightly.
The oils that were left have possibly cooked out then cooled down over a period of time, eventually breaking down completly to the point of failure.
Not entirely your fauly j1ggy.
Every days a school day we learn something everyday


----------



## DJ X-Ray (Sep 2, 2012)

AllenF said:


> As i said earlier product is at fault too slightly.
> The oils that were left have possibly cooked out then cooled down over a period of time, eventually breaking down completly to the point of failure.
> Not entirely your fauly j1ggy.
> Every days a school day we learn something everyday


Well it's not really the products fault if it wasn't fully worked or removed now is it? It's polish not an lsp,there shouldn't be any remnants of anything left on the bodywork.
Panel Wipe after every stage and i don't think the problem would have arisen.


----------

