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Spray cans.

Aerosol cans, rattle cans, what you should know about those.




Spray cans


Yeah! Let's talk about spray cans, also known as rattle cans and aerosol cans (paint). They all hold paint which is under pressure so you don't need a compressor to get it onto a car or a part of it.

Let me be very clear about those products, they are no match to the finish a compressor and a spray gun will provide. Of course I do use them, only for special needs. In this chapter I'll tell you all about it.

Spraycans



Let's start going back to "the good old days" when the ozone layer was no issue and pollution was something we took for granted. In those days metallic paint was a luxury, most cars were just white, red of black. Yep, getting old, talking about the 70's. Back then I could go to my favorite paint shop and order a spray can of synthetic paint. They would make the exact color which was on the car, faded or not they matched it! I don't know how to explain it but that stuff was so very thin it started to run at the least error I made spraying it. It was wonderful once you got the technique under control but it was soon to be replaced by acrylic paint.

The acrylic paint normally needed clear coat or a varnish or top coat if you like. Actually it is still sold in the spray cans we all know. If the laws and regulations about our environment never existed it would still be good stuff. Nowadays the gas that pressurize the cans is different and so is the composition of the paint that's in it.

That all makes it less evident to use spray cans. In the first place nobody fills spray cans locally anymore (on the mainland of Europe) but the factory. That leaves us with paint which is made to the car manufacturers paint code. It actually never matches the color of your car. It's a touch more blue or black, normally the metallic parts in it are different from the OEM paint. All in all it doesn't match the color of your car and over time it sticks out as being a bad repair. Even though you did everything possible to prepare the part for paint, it will show.

Spraycans



I painted this spot on the boot (trunk) of my car using a spray can, from the beginning the color didn't match and it only got worse over the years. This is done about 3 years ago but I'll leave it like this for the time being. I'm planning on doing a total respray of my BMW 740i using proper spraygun paint.

I know my car was not clean when I took those pictures, just read the rest because the problems are obvious.

I'll show you another problem with spray cans, If you're planning to use spray can filler then think twice! Even from the same brand the spray filler and the paint are not compatible. Just look at this part of my BMW 740i, It was fine for like 2 years but then this happened. It developed over time but this is something you absolutely don't want to happen! Yes, it's very close-up and nobody will see it at 90mph or at a distance of 20 yards. Still, you know it's there and you don't want that.



Spraycans



When you use a spray can containing cold galvanizer (which is actually great stuff but I'll discuss that a bit further on) putting your color coat from another spray can directly over it, may result in something like this.

Spraycans



Yes, it just cracked the top coat and the clear coat.

After all of this, is it still worth to use spray cans? Are they of any use? The answer to that is: Absolutely! I'll give you some examples where spray cans can be very useful. Just don't try to "repair" bodywork which is in plain view using spray cans.

Well, my last remark gave a great part away. You should only use spray can paint on parts you won't see, like behind bumpers and on the inside. The paint is not very resistant to UV radiation but out of the sun it will actually keep up quite nice.

Especially good are cans with galvanizing paint in them, only consideration is you have to give it enough time to react with the metal and to let the solvents evaporate. Leave it for at least a day, you covered the bare metal so that won't rust anymore. In normal cases you can just spray whatever spray can paint on it when it's dry to the touch, not with this.

Something you may not know about is there are different nozzles available for spray cans as well.



Mercedes



It all depends on what and where you need the paint to go, for bigger areas use the widest nozzle





Some things to consider:


Rattle the can! Like the manufacturer says you should shake it for 2 minutes to be sure the paint is mixed thoroughly inside, hold the can upside down. Do not just shake it, make a circular motion as well. They are called rattle cans for a reason, there is a small metal ball inside and if you can't hear it rattle while shaking, the color has sunk to the bottom, not mixed with the solvent.

Clean the nozzle when you stop spraying. Hold the can upside down and press the nozzle until there is no more paint coming out. You will see a difference in what is paint and what are the gasses which keep the can under pressure. If you don't want to clog up the nozzle do this every time you stop, even if it is for 10 minutes.

Move the spray can smoothly while spraying in horizontal lines about 25cm (10 inches) away from the object, be sure to overlap each pass by 50%. I've seen people using it like a paintbrush and making erratic moves, this will most certainly compromise your work. A little bit here and a little bit there is absolutely not going to work. You'll get runs and especially metallic paint will not give you the wanted results like that.

Warm up your spray cans. Paint becomes thinner when warm. In the winter I put them on the radiator of the central heating for an hour or so. If you don't have central heating or your wife doesn't agree to put your spray cans on it you can take a bucket with hot water and put them in there. Don't overheat the cans! I said warm them up, not boil them! Nice and warm to the touch is just fine. It will make your paint spread more evenly and by doing this you'll get a better result.

Don't use the cans outside under 15 degrees C (about 60 degrees F). The surface you want to get the paint on will be cold which prevents the paint to flow. You will get a horrible, very rough result. Chances are you will put more paint on the part to get that flow going, that will not happen! When it does it's to late, you can get the sandpaper out and start all over again.

Same goes for temperatures above 25 degrees C (somewhat less than 80 degrees F). The paint will be dry before it hits the panel or part, needless to say it won't give a good result either.

Just to show you what excessive temperatures, low or high, will do to your paintjob is in the next pictures.



Mercedes



Mercedes



The first picture shows the horrible orange peel, to get rid of that you will be tempted to put more paint on. That results in what the second picture shows. On top of the excessive orange peel we got runs! Yes, this is done using spray cans on my 1998 Jaguar XJ8.

The following picture is showing the result using spray cans (base coat and clear coat) done the right way. This is the way it should be! And yes, it's very well possible to achieve a result like this. Just to show you getting a good result from spray cans is very well possible. (Did I just repeat myself? I think I have! Never mind, you got the picture in more than one way now!)

Mercedes



Well, this concludes this section. Masking, wet sanding and whatever more you can do to, and with paint will be in the other chapters.

One thing, don't be discouraged when it doesn't work first time. Just sand it off and start all over again. The only thing which can be harmed is your ego. Happy paint spraying!


Last update : August 26th, 2018