Stone chip repair didn't quite go to plan....

[Ryanfsr]

Hi all

 

Had a slight mishap over the weekend with a stone chip repair on my bonnet....

 

Thought I'd done all the research I needed to do through reading a couple of guides on the processes of stone chip repairs; purchased myself some 3000 and 2500 grit Megs wet and dry, Skoda race blue touch up, DA polisher at the ready with an array of Merzerna polishes and Sonus pads etc.

 

It all seemed to be going so well at first - prepped the chips with IPA to ensure they were clean, and built the chip up through layers of paint applied with a cocktail stick, leaving each layer to dry for an hour or so (with a hairdrier positioned in a bike repair stand to aid in the drying process). Finished the final layer so the paint remained proud of the surface, and left that overnight to ensure it was properly dry.

 

Next morning I started on the wet sanding. Left the paper submerged in water and washing up liquid solution 30 mins before I started.
Considering I'd never done anything quite like this before, I thought best to start with the 3000, applying only very minimal pressure, and keeping the surface well lubed with the water and washing up liquid solution.

 

After 10 mins or so of sanding, the paint blobs were flush with the remainder of the body work and all was looking good! Have to say I was quite impressed with myself as I couldn't feel any inperfections when I ran my finger over it.

 

It was after this point I think I made the mistake, and probably should have started with the polisher instead! :(

 

On the tutorials and forum posts I read, I saw people mentioning clear coat/ lacquer, but didn't see within their tutorial steps them actually using it. So me being me, I applied a coat of lacquer and left to dry under the hairdrier again for several hours.

 

This of course stood proud again, and required wet sanding. It was during this wet sanding process I noticed the surface was beginning to look a little different, almost as if the water was repelling away from the area. Before I knew it, the patch was becoming dark, and I could see the primer coming through! Many swear words and objects were thrown around the garage!!

 

Car is now booked in to a local body shop to get an entire bonnet re-spray as is it pretty pebble dashed with stone chips; so I guess a good thing has come out of something bad.... sort of!

 

So question is, should I or shouldn't I have bothered with the lacquer coat? Or was I perhaps too aggressive with the sanding?

[Phil-E]

Doh!

 

I'd say you were too hard with your sanding.

 

Whenever I do stone chips I just fill them with a cocktail stick, leave to dry, blob of clear coat, leave to dry and then a polish/wax.

 

Once polished they are barely noticeable and they are at least protected from rust.

 

Phil

[sharky09]

Hi Ryan, my car is due to have some paintwork repaired on the tailgate & while it's in the Listers Skoda bodyshop (Coventry) they said they will repair a stonechip on the bonnet in the same way as Phil had described.

[Svend]

I mix 60% paint with 40% lacquer (three parts paint and two parts lacquer), works great.

You must of been very aggressive with the wetndry to go through the lacquer AND the paint to get to the primer. Ouch.

I always suggest getting a large panel from a scrap yard to practice on. Learn the technique and knowing when to stop and go onto the compound and then polish.

[Ryanfsr]

Thanks for that chaps! Its just considering I've got all the DA polishing kit and pads I'd thought I'd try and do it a little better.

 

Perhaps it was my sanding technique.... although I have to say I was putting on as little pressure as I could (literally enough just to ensure my finger gripped the paper)

 

This is the forum post I was following: http://www.detailingworld.co.uk/forum/showthread.php?t=20127

 

I'm just wondering if the lacquer is actually required? By the looks of it from here, the author didn't use any, just simply layered the paint until it sat proud of the surface? :S

 

Good idea Svend! Might have to make a trip to the local scrappy this weekend then!

[Svend]

The first time wet sand can be daunting and can go wrong. So practice on a small section at a time on a scrap panel and you can see how your progressing.

Everyday is a learning day just find your own pace.

Bonnets are the best really as they are so large and invariably have a ridge either down the centre or down each side, as you get more comfortable you can take it up a notch to touching up ridges and bonnet edges (everyone has a small chip in a door edge where someone has got out in a hurry and the metal of the seatbelt has caught or opened the door onto a high kerb, etc...).

[Ryanfsr]

The cars going in next Tuesday, so I think I may give a couple more of the many chips on the bonnet a go as practise without the risk of screwing up again!

 

Certainly take into consideration that less is more though as far as applied pressure on the wet and dry goes

[summerof44]

Its better if you start wth a coarser grade paper, 2000 or even 1500 to take the top off the high spot you create when touching in. If you use an ultra fine grade to start with it tends to ride over the high spot and you take off paint from the surrounding area. Also make sure you use a small block no bigger than an inch square made from a hard material