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A guide to DIY & Body Sprays Part-1

Body Beautiful Published: 13th Jun 2011 - 0 Comments - Be the first, contribute now!

A guide to DIY & Body Sprays Part-1
A guide to DIY & Body Sprays Part-1 The Earlex has a Teflon-coated paint pot to make it easier to clean, the hoses and cables stored conveniently and compactly in the base unit and there is enough air pipe to do the whole side of a vehicle without stretching
A guide to DIY & Body Sprays Part-1 We found the paint went on very orange-peely initially, but this flowed out to a smoother finish before drying
A guide to DIY & Body Sprays Part-1 More importantly, the blend of shades was very good: you could tell that one end of the door was a different colour to the other, but you couldn’t see where it changed
A guide to DIY & Body Sprays Part-1 Be patient and build up coats of colour slowly with aerosols to avoid getting runs
A guide to DIY & Body Sprays Part-1
A guide to DIY & Body Sprays Part-1 New plastics need all trace of mould release agents to be removed before they can be sprayed
A guide to DIY & Body Sprays Part-1 This MINI’s bonnet intake’s lacquer and base coat were lifting from the primer. Sand back as far as this before reaching a sound base of primer. Only then can it be sprayed - cutting corners will not work…
A guide to DIY & Body Sprays Part-1 If there’s no damage to cover, concentrate on putting a thin coat of primer to get a good finish, rather than trying to get a good build
A guide to DIY & Body Sprays Part-1 Primer can be applied by brush and flatted back for rapid build and zero over spray
A guide to DIY & Body Sprays Part-1 Using a curve can help blend a localised repair invisibly into a larger panel. As with all paint cans, shake to mix thoroughly first
A guide to DIY & Body Sprays Part-1 It is not a cheap way of buying paint, though. These cost (from left to right) £11.63 for the adhesion promoter, £12.51 for the high build primer, £12.87 for the mixed base coat and £12 for the single pack clear coat.Bare metal would need an etch primer, too
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The quality of the paint is the yardstick by which every car is judged, so is spraying a job we should leave to the professionals? Simon Goldsworthy investigates the DIY options

Let’s get one thing out of the way right at the start: I have seen some remarkable DIY results on cars sprayed in less than ideal surroundings, so yes you can achieve a good paint finish using the basics at home. On the other hand, I have also seen some very disappointed owners with cars that looked worse after painting than they did before. I mention this because there are no hard and fast rules when it comes to painting your car, only guidelines. A further point worth mentioning at the start is that the refinishing industry is subject to ever-more stringent controls in the paints they use and the facilities they must have. These controls are there to protect both people and the environment, and while non-professional use does not yet come under the same legislation, the days when neighbours are happy to stand idly by while you carry out a full respray on the drive are long gone. The paints we can buy have also been undergoing some changes. Manufacturers are no longer allowed to make two-pack paint, although there is still a limited time in which existing stocks can be sold and there is no limit to how long the end user can hold onto those stocks before putting them to use. Cellulose may still be manufactured in limited quantities and sold for use on classics, but the regulations and controls for this system do seem to vary fromone local authority to the next. There are, however, no restrictions on cellulose in aerosol cans. Meanwhile, the professional trade has moved almost exclusively over to water-borne paints (although still with two-pack clearcoat lacquers to protect it from the elements), a move that was much feared but which seems to have been relatively smooth and easy. The net result of all this is that there are still a number of paint jobs you can safely do at home. Small touch-up repairs of minor knocks and scrapes are obvious examples, as are painting new accessories to match an existing body. You may also have a new panel or a repair that needs blending into the rest of the coachwork. These are the repairs I will look at in this feature and, assuming that you do not plan to do enough painting to justify the expense of a conventional compressor and spray gun set-up, I will start by looking at a couple of more affordable alternatives.

Plastic Fantastic

Modern classics with their plastic bumpers and spoilers, need special treatment. Some of us have at some time or another needed to spray small items such as mirror covers or door handles. And a fair number of us have also had that sinking feeling that comes from painting plastic trim on Sunday afternoon, only to find all the paint lying on the floor on Monday morning! Or perhaps you remember painting a tiny blemish, only to end up with a splodge that gets bigger and more noticeable the more you try to blend it in? In neither of these cases is the aerosol itself at fault. Just like any other paint, you need to buy the correct one for the job and a lack of adhesion simply means that you have got the wrong stuff. When painting plastics, you need to use an adhesion promoter, followed by a primer and topcoat that are specifically formulated for use on plastics. with added plasticisers to keep them flexible. Fortunately you can buy all of these paints ready-mixed in aerosol form, and most paint factors can mix up a base coat to match your vehicle and put this in an aerosol on the premises too.

Once you have the right products, with care and attention you can actually achieve some very good results over small areas.

The first step for painting new plastics is to get rid of any traces of mould releasing agent that will stop the paint from adhering. You can do this with a quick waft of a propane torch to draw out the mould releasing agent, allowing you to wipe it off with panel wipe or degreaser. Alternatively you can use a Scotchbrite pad dipped in spirit wipe to help draw out the release agent. (Panel wipe is such a mild solvent that it is rarely a problem when used on plastics, but remember that some plastics are solvent sensitive so if in doubt, test on an inconspicuous area first.) You can also buy dedicated plastic cleaners that are waterborne if the piece you are working on is particularly delicate, although these will inevitably work out more expensive. Whatever you use, wash all traces off with a clean Scotchbrite and soapy water before drying thoroughly. If you are re-painting an existing piece of plastic, you will need to sand back any paint that is flaking away. Use a fine 600-grit paper to get the paint off without scoring the plastic. If you can get back to sound primer without going through to the plastic, then you will not need to start off with an adhesion promoter but can go straight to the re-priming stage instead. The air intake surround in the pictures is a good example of a component that can be painted off the vehicle, where a good match is the goal rather than perfection. But sometimes you need to blend a small repair into a larger panel. Thisdoesn’t always go to plan, an inability to make the repair blend in invisibly being down to either poor paint match, poor coverage or even asking too much of a localised repair. It is vital that you assess carefully the repair you are undertaking and decide on the appropriate way forward. In the case of the plastic air intake surround, this was small and could be painted in isolation so it was ideal aerosol fodder. The vehicle we used also had a slight ding on the front bumper, which was certainly small enough for an aerosol to cope with, but it was also on quite a large panel. Fortunately the shape and position meant that we could keep the repair localised and still blend it in unobtrusively around the sharp radius in the panel adjacent to the problem area. But there was also a third blemish, a small stone chip on one door that had been left untreated and allowed to rust. This may have been the smallest of the three problems, but its location meant that it was not totally suitable for an aerosol repair. Starting with the bumper, these are particularly prone to getting tar spots, so it is important to make sure you get it all off when preparing the area with a Scotchbrite pad. When keyed up properly, the Scotched area will be dull and noticeably different to the surrounding paint. If there is any kind of dent, it will need to be brought up to level with filler. This only needs to be a fine grade, and can be sanded back with 120grit paper, working up to 600 grit which is as coarse as you can expect an aerosol primer-filler to cover. When the primer is dry, go over the area with a guide coat. This is just a very light dusting of a contrasting colour (any old aerosol would do the job). Then, when you flat back the primer, any low spots that need further building up will show themselves as black flecks. You can also use this to see whether any pinholes will flat out before reaching for the stopper. A car’s bumper needs more build of paint than the air intake surround, which has to be built up with a lot of thin layers rather than one or two thicker ones. Fortunately the high solvent content means that the aerosol paint dries very quickly. As an alternative to aerosols, it is perfectly acceptable to use a brush as a simple way of getting good build of primer. The trick is to make the primer a little thinner than normal to help the brush marks flow out, and to use a guide coat when flatting this back to ensure that all brush marks have been taken out. When using the aerosols, there is no separate air feed and it can be difficult to mist it on gently. You need to pull the can further back than you would a gun (up to 16 inches back) and be bold with the nozzle to avoid it coming out blotchy. When you have finished with an aerosol, there is no clean-up as such. But do invert the car and depress the nozzle briefly until it blows clear to clean out any residues that might dry and block it for the next time.

Let us spray…

The first of these is an electric spray gun that does away with the need for a compressor altogether. We’ve seen 80W sprayers like this advertised for as little as £12.99 and, although it would be a big ask for this kind of gear to spray a decorative finish such as vehicle paint instead of creosote to preserve the fence, better things can be expected of equipment such as the Earlex Spray Station Pro. This retails from around £175, making it comparable to a budget starter kit of compressor and gun. The electric sprayer does have the advantage that unlike a small compressor, it will never run out of puff and keeps on spraying without a break for as long as there is paint in the cup. Also, the Earlex is an HVLP (High Volume, Low Pressure) product, which keeps the transfer efficiency very high. Basically this means that more of the paint that leaves the gun ends up on the panel, and this can be an important consideration when painting at home in the garage because there is very little bounce back and overspray to cover everything else stored alongside the car. The important question, though, is how does the finish from a tool such as this compare? We found that atomisation is not quite as good
as it is with a conventional gun.This is not a problem with primers where the thick coating laid down by the gun gives the build you need which can then be flatted back, but we did wonder how it would cope with fading out localised repairs if the spray was getting a bit blobby at the extremes. To put this to the test, we coated a door with silver, then changed the tint and faded this in from one end. We were very impressed with the results, being unable to detect where one colour faded out and the other faded in. It is fair to say that the Earlex Spray Station Pro has a different feel to a conventional compressor and gun. If you are used to spraying with the latter, then you will need to watch how the material goes on and adapt your style to suit. So, for example, a narrower fan gets better atomisation, but then you need to move the gun more slowly and make consecutive passes in smaller steps. Turning the air cap to an angle of 45degrees reduces the fan even further to a round jet, and this can be useful for particularly complex shapes such as bumpers and spoilers as you can make plenty of passes without excessive build-up of paint and the consequent risk of runs. But all in all a good little kit we reckon.

It’s in the can…

When spraying with aerosols, the biggest problem most people get is that they put it on too heavily and then get runs. You cannot vary either the pressure or the fan size, so the trick is to flick the primer over the workpiece lightly and often, building upwith lots of thin layers. It is essential that you remain patient and vigilant to avoid runs. The first coat will look like little more than a guide coat. The outline of the primer will still be visible through the second, while the third will only just start to obscure it. You shouldn’t be trying to blend the paint into the surrounding panel until about the fourth coat. Do this by standing further back and flicking the can away from the repair at the end of each pass.

Rid rusty stone chips!

Rusty stone chips are more of a problem. Trying to blend in very localised repairs is only really viable if you can keep within a hand span of a panel’s edge. In this respect, you can use a swage line as a panel edge but our stonechip was on a large and flat panel that was highly visible. On something like this, you can blend in colour using an aerosol, but you would struggle if you had to clearcoat such a large area using a plastic nozzle. Quite apart from the cost involved, you can’t vary any of an aerosol’s basic parameters (fan size, air pressure, mixture etc) so there is more chance of getting splutter or dry spray when attempting to cover such a large area and the end result would inevitably be stripy. Start off by using 600grit paper to take the damaged area back to metal, and then follow up with 240 and 120 grit paper as necessary to get the rust out of the ding. If a particular ding turns out to be very shallow, you could get away with just using a can of high-build primer to bring the blemish up to level. But if the damage had gone through to the metal, you first have to blow on a little etch primer.



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