How to do Stone Chip Repair &
By Danny Argent : 27th April,
Last revision: 29th May 2010
Note: over the years, people keep
asking me questions about this article, and I keep adding the answers...
this article is now very long, so...
for those too busy to read this, an abridged version can be found here.
(After a little re-organizing, we now have a new Car Scratch Repair page)
Stone chips and other minor damage looks unsightly once it begins to accumulate, especially on dark coloured car. But worse still, because the stone chips, scratches and scuffs have penetrated your paint, you car will be prone to rust. Once rust sets in it is very difficult to remove.
Although stone chips are small, they do have a huge effect on the appearance of your car, making it look tatty and therefore devaluing it considerably. At Clean Image, we can take a 3 year old car and valet it clean, polish and buff the paintwork, remove stains from upholstery, we can refurbish the wheels, remove dents and carry out smart repairs that get rid of scuffs and scrapes.. and otherwise make it look like a brand new car! But the biggest difference between a valeted car and a brand new car will be the amount of stone chips.
We strongly recommend that when you collect your car from the dealers, you also collect a touch up paint of the appropriate colour (you can get the right one from their parts department). You should then check for chips every time you clean your car and touch them in as soon as possible.
"I'm no artist"
I am often told by customers that they are no good at it, or that they don't have a steady hand. In all honesty, it's far better to paint your stone chips and do it badly, than not do it at all. If you end up putting great big splodges all over your car, it isn't really a problem as they can easily be removed and the touch-ins re-done by somebody more skilled at a later date, meanwhile you are protecting the chip from the elements and preventing rust.
It's hardly surprising that so many people have problems applying touch in paints, because without exception, the brushes supplied with touch in paints are universally useless! In most cases the brushes are way to big. Some companies now supply smaller brushes which can be used for light scratches, but these are way too thin, and because they are plastic, they won't hold enough paint as it all drips off.. usually down your bodywork!
Get a decent brush
The solution is really rather simple, go to an artists or hobby shop
and buy a size 1 brush. You don't need to spend a fortune on finest
Kolinsky Sable, most brushes will do. This makes the task of touching
in about 1000% easier, this will allow you much more control over the
paint and allow you to put the paint inside the hole caused
by the stone chip, instead slapping it on like a large band aid over
the whole area.
The only problem with this solution is that you will need to clean the brush or else it will go hard. So we also suggest you buy a small tin of Standard Thinners from Halfords or your local car accessory shop. It's probably best that tell them what you want if for, and ask advice to make sure you get the right kind (white spirit and normal brush cleaners will not work). The correct Thinners can also be used for thinning the paint which will give you more control when touching in thin scratches, and of course, you can use it on a soft cloth to remove any accidents you may have.
The alternative to all of the above is to use a cocktail stick or matchstick. It's not a method I can get along with, but many professionals do it this way with great success.
(From left to right) A Ford touch in paint, Holts Dupli-colour
mixed by Halfords stores and a Peugeots touch up paint.
Types of paint and touch-in kits.
In the vast majority of cases, modern cars have a type
of paintwork called 'Clear over Base'
(Click here to a see a page with cross section diagrams). A layer
of primer is applied to the car, over this is applied a fairly thin base
colour, which is the colour that you see. And over the top of this is
the Clear-Coat, which is a clear lacquer. Because there is such a thick
coat of shiny lacquer over the base coat, there is no need for the base
coat to have it's own gloss, this is why often times it is supplied as
a matt finish.
So now you know how modern paintwork is constructed, this will help explain the vast array of bottles you may find in your touch-in kit! Most kits from a dealership will include the base coat and the clear coat (top coat or lacquer), while halfords kits sometimes include a primer as well. Other motor accessory shops may supply a single paint with a gloss version of your colour which does not need clear coat over the top. You will also find this to be the case with services which mix the paint for you while you wait.
(The Pro-Arte series 31, size 1 seems to be best suited)
Kits may also contain strange plastic objects for removing rust, miniature wire brushes and/or sanding pads.
If you are not able to readily find the correct touch up paint, you may be able to buy the correct paint in a spray can. You can spray this into the lid and brush it on from there.
Update: If you can find the correct paint code (which is stamped onto a metal panel or thick silver sticker which is located either under the bonnet, inside the door shut, and more rarely in the boot (Audi). If you can't find it, or the panel doesn't have paint code numbers (which is sometimes the case with cars like Cryslers and Fords) then phone your dealer, they should be able to tell you the paint code from the registration number -- or if you have fitted private plates, from the chassis number) then you can order touch up paints online from companies like FIXACHIP (please visit their website and take a look, they have a video which shows you how to fix your stone chips).
Types of paint and touch-in kits.
Inspect your vehicle to get a good idea of the areas you have to do and how many chips you have to deal with. Most stone chips will be on the front of the car around the grill and lights. Another place to pay careful attention to are the wing mirrors. Some cars have an annoying habit of throwing up stones and their own sills, so check around the bottoms of the doors. You should also have a good look along the edges of the doors and boot, and don't forget to check inside the door shuts. Often there are small chips and scratches cased by people's feet.
You don't want to be painting over tar spots or squashed flies, so use a suitable cleaner to remove these before you begin. Your car should be clean and dry and any loose flakes of paint should be removed. Some people recommend de-greasing the area with an alcohol swab.. but these paints have enough solvent in them to cut through any waxes remaining on the car. I have yet to see touch-up paint bubble-up or fall off!
You should follow the manufacturer's instructions on the side of the touch up paint. It is important to shake the tins for a good long time, especially with metallic colours as the metal flecks can sink to the bottom of the bottle. We recommend decanting the paint into a suitable container which means something you can throw away, do not use the china tea set that was given to you as a wedding present (using a container means that you can have 'just enough' paint in it, meaning there is less to spill, and you can stir with your brush so that the metallic flecks don't sink out and you don't get your brush in a mess). And do not use plastic or styrofoam cups as the solvents in the paint will eat right through them and the paint will pour through the bottom. The best thing to use is the plastic lid of an aerosol can. You can then dip your brush in the paint and begin. You should aim to fill the small hole left by the stone chip and no more. The same goes for small scratches, less is more, aim to cover as little area as possible, just enough to hide the damage. If you feel you are competent with a brush, then feel free to go the full hog with your touch in kit. You can apply the primer, then the base coat, then the top coat.
But few stone chips go through to the bare metal, usually they chip off the top coat exposing the primer, so there is no need to re-prime. Each time you add a new layer of primer, base and lacquer, you need to paint a slightly larger area to cover the one below, so the less layers you put on, the better. Usually, we save primer for when a large chip has occurred, or we have had to repair an area of rust. If you find that you have very many stone chips to do, especially lots of small ones, it would be a huge chore to have to treat with base and clear-coat. A simple way of getting around this is to mix the base and the lacquer together. This will make the base coat glossy. If you are touching up a silver coloured car, or a car with high metallic fleck, remember to keep stirring the paint, and try to get the paint on as thin as possible.
Silver paint is very, very hard to match because there is very little actual colour to it, the colour is made up by the metal flecks. If you find that your colour matched paint looks a little dark, it is because it is designed to be sprayed on (see below) - and answer to this problem is to buy a different paint for a lighter coloured silver car. We have found that Mazda silver works best on most silver cars. When you are done, don't forget to clean your brush with the thinners!
Invisible mending - is it possible?
Although there are many companies doing a stone chip touch-in service, very few will follow any methods much different from those described above. While there are other techniques for dealing with stone chips, there is virtually no way to make stone chips vanish with an invisible repair, and the methods that do exist are far from being cost effective because they are much the same as used on any other smart repair.. the area may be scaled down, but there is just as much work that goes into it.
One of the biggest problems is that so many cars these days are metallic, and the higher the metallic, the more problematic it is. Silver is the worst colour to deal with and you may have noticed that it seems like half the cars on the road these days are silver.
The problem is gravity! The metallic effect is simply aluminium flecks suspended in the paint. The colour that the paint ends up much depends on how the aluminium flecks lay. When you brush on a metallic paint, you tend to apply a small droplet of paint, and gravity will cause the heavy metal flecks sink to the bottom of the droplet. What you will end up with is a dark patch at the top of the droplet and a very metallic patch at the bottom.
The only way to avoid this is to spray the paint on using an air brush. This is the method used by many professionals, but this has even bigger drawbacks. Airbrushes can be hard work in themselves (as anybody who has ever used them will know), any airbrush capable of spraying a small enough area is going to be expensive, delicate and likely to clog-up and splatter when spraying metallic car paint. Normal air brushes spray far too big an area and bigger areas are far more noticeable when you STILL don't get the colour to go on exactly right, which often occurs because your coat of paint is not coated with a thick layer of clear coat.
But the main problem with the airbrush technique, is that the paint goes on so thin that it does not fill the hole caused by the stone chip. This is usually a problem with any kind of stone chip repair. Even when coloured in, you are left with highlights and shadows caused buy the texture. You can fill the hole with paint, but as the solvents evaporate from the paint, the paint will shrink back, paint that is sprayed on is thinned with even more solvent and so goes on thin and shrinks back even further.
The one technique that can work is to keep filling the holes with paint until the the paint actually causes a raised bubble. This bubble can then be flattened and polished. Sometimes if this operation is successful, the repair is almost invisible. Unfortunately it hardly ever works well on metallic cars, only those with a plain base colour such as red, black or white. The other problem is that it can take a very long time, as each layer of paint can need to cure (depending on the colour, for up to 24hrs, white takes a very long time to fully harden). And when all this is done and it comes to flattening and polishing, you will find that this new paint is a lot softer than the original paint, if it is a lot softer, it may just all polish straight out of the hole again, leaving back at square one. Heating the paint with infrared helps with this.. but as you can see, it is a process reserved for specific areas of damage such as scratches and large chips in noticeable areas, it is certainly not cost-effective or appropriate for large numbers of tiny stone chips.
If you have a large number of small stone chips, especially if they are really small, using a colour wax may be a better option than trying to paint all of them in. We have found that the darker versions of the wax usually work best - so if you have a car which is a medium blue, don't use the medium blue colour wax, get dark blue instead, same goes for all the colours.
Due to popular demand! Colour Wax update:
Colour wax is pretty good stuff, although it's not a permanent solution - it will last a few weeks.
It is a wax with a strong dye in it, you put it on, wipe off the excess and it will leave coloured wax in the holes. I wouldn't recommend trying to wax the whole car with it, use a normal wax for that, and then just apply colour wax where the stone chips are. It will also cover some scratches.
Again, it's not a magic solution or an invisible repair, but it will take your eye off chips and light scuffing, especially on low down areas. (See slide show below)
Highlights show up far more than shadows on a car, in fact, if you look at the picture above, you are seeing the scuffs because they reflect more light and appear highlighted. The reason I mention this is because you can't always get the colour you want for you car... so go for a darker colour. I used a dark blue-grey on the car above and that worked about as well as you are ever going to get. You will find that just using black will work better than nothing on blue, red and green cars (I doubt it would work on yellow!).
You can also mix colour waxes together, if your car is a bluey/purpley colour, then you can mix some red into a blue -- although, if you are aiming to go darker that the actual colour of your car, then mixing blue and burgundy might work better.
We must stress however, that this is a quick fix, and that it doesn't work for very long. Without a doubt, it is better to touch in stone chips and scratches with paint. Color Wax is fantastic for the really tiny ones that it's just not practical to do with a brush.
Preventing stone chip damage
One simple method to limit the damage of stone chips it to get a plastic
film fitted to the areas of your car that are prone to stone chips such
as 3M VentureShield.
This clear plastic coating is virtually invisible but is thick enough and soft enough to absorb most of the impact. Many cars such as TVR come with this kind of film already fitted but you can buy aftermarket versions for most popular makes and models.
The kits are designed to cover the areas most commonly damaged by stone chips on any given vehicle. The prices vary from about £300 to £600 pounds depending on the size and complexity of the kit. When you consider the cost of a front-end respray, or even the cost of a replacement headlight unit on sports cars, this is a very worthwhile investment.
Paint sealants will also help, because they fill the microscopic pores in your paintwork and coats your paintwork with a thin layer of PVC/PTFE, this all makes the paintwork stronger and less brittle - stones hitting your car are less likely to cause damage, and if they do the damage will be minimized.
But the best way to avoid damage from stone chips is to avoid getting hit by stones in the first place.
A traffic policeman once told me that stone chips is one of the things they look for when they pull people over for infractions of the law.. people with more stone chips are more likely to be treated harshly. This is because aggressive driving results in large numbers of stone chips, so if you tell a policeman that you will never do it again, they are more likely to believe you if your car is free of stone chips. Insurance assessors are also familiar with this method when inspecting crash damage, it is useful for them to know how aggressive drivers are.
If there were no other cars on the road, your car would get no stone chips, this is because stones are lifted up from the road by the tyres of other cars. So the more distance you keep between yourself and other cars, the less stone chips you will get.
Stones are not usually 'flicked' up in the air, and they certainly don't fly around like bullets... if they were, they would be of far more concern to pedestrians and cyclists than motorists! No doubt there would be dozens of injuries every year and stone chips would be a national issue.
Mostly stones are lifted into the air when your tyres get warm and soft, they are tossed a couple of feet into the air no harder than you toss a pebble underarm. Usually it has no force to it at all, it is your car which has all the force... if your car drives into an airborne stone at 30mph, you will have a 30mph collision - and if you are on the motorway doing 90mph you will have a 90mph collision!
The good thing about stones is that they aren't very 'floaty', so after being lifted into the air by the car in front of you, they don't hang in the air very long. Nor are stones very 'bouncy' so the don't bounce back up in the air once they have hit the ground again. What this all means is that the car in front of you is lifting up stones, but this danger area is actually a fairly small arc, by avoiding this arc, by leaving plenty of distance, and by keeping your speed down, you will avoid most stone chips. Although you will still have to contend with stones from oncoming cars and those occasional stones which are flicked hard, so we do recommend paint sealants and special plastic coatings.
Other causes of paint chips.
Chipping along door edges is another problem altogether, this is caused by bashing your doors against things that they really shouldn't be bashed against. So be careful in car parks - That's about all we can recommend! We could suggest that you get those door edge protectors, but in truth, the clip on ones do more harm than good as they slide about scratching your paintwork, they also trap dirt and moisture which can lead to rust. The self adhesive type are much better but do nothing to enhance the looks of your car. And besides, you should still be careful as even if you don't damage your own car, you could damage somebody else's.
If you park in your garage, car port or some other tight spot where you always have to be careful of your door edge, then being careful isn't likely to be good enough... it's what we in the trade call "an accident waiting to happen". In such circumstances door edge protectors would be a good option, IF there weren't a better option, which is to put the protectors on the walls instead. It's a simple idea, but it does work and we have written a review on some of these products here.
The final word.
Don't forget to clean your brush!
Update - Since writing this article, have been let in on a trade secret used by some of the old-timers. If they have a car with many stone chips, they pour paint onto the area then spread it around with a large rubber squeegee, before squeegeeing off the excess. This makes a hell of a mess you won't be surprised to hear, but the answer is to use a rotary buffer to polish off the excess after the paint has dried.
As yet, I haven't been brave enough to experiment with this method, but if anybody wants to lend me a car I can practice on....
Further Update: During 2006, Innotec (who sponsor and supply most of the polishes, waxes, solvents, glues etc. for Pimp my Ride UK) were kind enough to lend me their professional stone chip kit. I have to say, it was the best one I have ever tried. Anyway, because of the way it works, I thought it were a good contender to the afore mentioned technique.
I poured the paint over a section of bodywork and then proceeded to used a rubber squeegee to spread it over an area of about 8x8". What you then do is take a sanding block and wrap a soft tissue around it which you then soak in their special gel, which is a solvent much like paint thinner. Then, very, very, very, very gently you rub the sanding block, tissue and gel over the area to remove the excess paint.
It does work, no doubt about it. However, it
causes such a mess!
When you squeegee the paint on, capillary action pulls much of the paint out of he chip again, so although the hole is coloured, it doesn't leave it flush with paint. No matter how gentle you are when removing the excess paint, or what tissue or solvent you use, this can still pull more of the paint out. So in conclusion, while it works, the results on the chips are no better than you might otherwise get. It's also very time consuming to clean up the mess. So it's a technique I'd only use on a car with thousands of chips which would otherwise take hours to touch in by hand. Also Innotec paints are expensive and the technique is very wasteful (and I apologize to Innotec for using up most of a bottle of Dark Blue!!!)
It's also a good idea to use non-metalic versions of the colour you are using. When you are wiping off the excess, the 'paint' was comming off, but the aluminium flecs stay behind, guilded into place by the paint under them -- it takes a lot of work to get them off, and this extra working can remove the paint out of the stone chips.
Please note - this is not the way in which the Innotec kit was originally intended to be used. so any short coming of this technique are not down to Innotec, in fact, I have tried the same thing with normal paints and thinner and the Innotec gear in much better.
More Notes - Unfortunately, Innotec stone chip paints are not available to the general public being a trade product. However, I highly recommend their range of other products, soon to be available to the public through www.valetshop.co.uk