Firstly the cheapest way is to get those cans from KMart or BigW from brands like Holts DupliColour and PowerPlus they should have your colour in stock, however these paints are abit dodgy and i don't think it will match your paint.
If you want to spend more but decent quality go to a auto paint mixing place and get the paint code of your car and get them to make a pressure pack for it.
Paint colours fade over time (how's that for a newsflash?) so the stock colours, whether they're cans or mixed to specs by a shop, might be accurate but won't match your car.
One solution is to look at other colours for any make in the spray can range and, judging by the lid colour relative to your stock colour's lid, go a bit brighter or darker. Another is to get a paint sample off your car to a store that has a computer matcher and get an exact match. You might be able to get a small painted part off, like your fuel filler door, and fit it into their analyser.
Exact colour matches are more critical on horizontal than vertical surfaces. It's to do with eye lines and light angles. I've used spray cans on vertical panels and they looked fine from any angle and in any light, but the same colour wasn't satisfactory on the bonnet and was worse in some conditions that others, although generally it wasn't all that noticeable unless you were looking for faults.
If you haven't done it before, the preparation is critical and the end job will only be as good as the effort put into the preparation.
P.S. I'm more reliable on this than the source of mystery beeps!
Thanks for the reply EA S. I only need to paint the driver side door sill where the previous owner had put a deep scratch on it. It's not that noticeable, but it annoys me nonetheless. I also need it to paint the new door pods that I made. I think it would look pretty good painting it the same colour as the car. So basically, the colour doesn't have to be a dead match for the exterior, as long as its close enough.
You can get your paint colour mixed up and put in a spray can from Autobarn (not sure of price) but they just mix the formula in the book and as EA S said the colour might be a smidgin different because of fading. Test it on some obscure part of the car first, maybe the inside of your petrol flap.
If you only want to paint the sill why dont you paint the whole sill.....by masking off the doors/ gaurds etc and coating the whole sill you wont have to "blend in" with the color already on the sill. This will give a better look once the job's done without making the doors/sill color difference too noticeable.
Remember not to paint straight over bare metal!! always use primer first as paint wont stick.
Botch is right. The best way to paint panels is to do the whole section between breaks, such as the bottom half of a door from the bumper strip down or the whole sill, rather than just small parts. The break to the next section, like the door gap, fools the eye if there's only a slight difference in shade although it mightn't fool the eye if the two shades were adjacent on the same panel.
Apart from primer, if there's a scratch make sure you fill it or at least sand the edges so it feathers in, or it'll stand out under the new paint. Auto paint has NO filling capacity, and spray primer/filler doesn't have a lot. Spot putty is best for small holes and scratches that are too big for primer/filler.
I've sanded the scratch out and feathered the surrounding area. I've also got the primer on it. So you're saying I should paint the whole sill? How would I prepare the sill? I was thinking just to give a sand to give the primer something to bite onto. Is that all I'd have to do?
Um , maybe bad news coming. Did you prepsol (wax and grease remover) the area before applying the primer? If not you risk problems in future, and your choices now are to remove the primer (sand back and/or strip with thinners) and prepsol it properly, or press on and see what happens later. It might be alright, or you might have to do a lot more work to fix it up.
Prepsol is necessary to clean wax and grease and especially silicone, which will cause fisheyes (little craters with visible rings) or other imperfections in the finish. Be very thorough if you've used polishes on car. Sanding first as below will help if you have.
No need to sand for a key and doing so might give poor base which will mar finish, but a clean with 1200 or preferably 1500 (you'll get 1500 at decent paint / auto paint stores but 1200 is best most hardware stores seem to carry) wet and dry is good. Get a bucket with a bit of plain soap or dish detergent and sponge it onto area you're working on to keep it lightly lubricated and remove debris while you're sanding. Wrap sandpaper around another firm small sponge (common kitchen ones about postcard size and quarter/half inch thick) to get flat contact with sill and follow contour. Prepsol after sanding.
Make sure filler is sanded right down flat and feathered on edges where it joins paint. Run your flat hand (not just fingers) over it while sanding to check. If you can feel any lines or bumps, they'll show in the finish, maybe a lot more than you'd expect. Finish filler with 1200 wet and dry same way as above.
Be sure to prepsol the whole area to be painted before applying the paint. Give it two or three goes, using a fresh clean cloth each time, rubbing firmly to get stuff off, and wiping dry with a different fresh clean cloth. Make sure primer is fully dry from prepsol before painting. Tack rag before paint coats is recommened to remove all dust, but I've never done it and no problems to date.
When spraying, do light coats. Don't expect first coat to cover fully. If you can still see primer through it it's ok. Build up several coats of same density. You can usually recoat after 5 or 10 minutes, or whenever it's dry. Trying to put thick coats on will cause runs and sags. Half a dozen light coats is better than two or three heavy ones.
Overlap each spray line and keep working in wet paint. Spray can paint dries quickly and as you're doing a long narrow strip might be better to break it into three or four short sections to stop running into dry paint when you get back to start.
Just a hint on masking tape, from someone who found out the hard way. Get proper auto masking tape and be careful pulling it off - it's a real bastard when you pull off chunks of paint with the tape.
Hey EA S, you definately know your stuff in terms of painting. Thanks heaps. When I sanded the paint around the scratch, I cleaned it up with alcohol. I'm not sure what Prepsol is exactly, but the alcohol seemed to do the trick. The primer has been on for a while now (~2 weeks), and it seems to be on alright, so I might just do as you say and prepare that properly and just give a final few coats of the proper coloured paint once I get it. Thanks again.
Prepsol is sold under various terms but main ones are probably prepsol or wax and grease remover. K mart have it in their section and K&N at Repco and Autobarn - you should get it at any auto supplier that sells auto paints or spray paints. Only costs a few dollars and it's critical to clean with it first.
I don't know for sure, but I think that primer might be more forgiving with prepsol preparation than paint, and alcohol has got to be better than nothing, as long it's not incompatible with filler, which hopefully it isn't much if it's still ok after a fortnight. I'd still go for the prepsol before the paint as the alcohol might be incompatible with the paint, unless someone else knows if it's ok.