Vintage Motocycle Club
Long before the advent of cellulose paint and spray painting we relied on the technique of coach painting with brushes to protect the metal and timber surfaces of locomotives, early motorcars and horse drawn carriages etc.
I have been using this technique in the restoration of my motorcycles for the last 30 years. I first became aware of what could be truly achieved with a brush after talking to an entrant at the VMCCís annual Saundersfoot run. I believe he had previously worked in the development department at BSA where they took pride in such a finish. His name was Tom Barker and his pre-war 250cc BSA had a totally stunning finish.
A number of folk have recently asked me how I do it. So, I have put together some notes to help anyone who might wish to give the method a try. A note of caution though, it requires a certain amount of time and patience to achieve a good finish. It is though, very satisfying when folk later approach you and enquire who sprayed your bike! They simply canít believe you can achieve a mirror finish using the humble paint brush.
Ideally all metal surfaces should be taken back to bare metal. The easiest way to do this is by blasting with a suitable grade of fine grit. Sand blasting is now banned on health & safety grounds. A further note of caution, I would never grit blast either a petrol or oil tank as there is too much risk of grit remaining, especially inside the oil tank. Should this find its way inside your carefully rebuilt engine, then you have another expensive rebuild on your hands. Grit or Bead blasting is the best way to deal with rusty surfaces though it requires a gentle touch, particularly on delicate sheet metal pads.
My preferred method for stripping paint is to use Nitromors Paint Stripper and a stiff wire brush. I then finish off with emery cloth paying particular attention to any areas of rust. Having cleaned the surface to your satisfaction, wipe the surface clean with white spirit and when dry coat with a proprietary rust inhibitor. I use Duckhams Jenolite which has a high phosphoric acid content and serves to neutralise existing rust and inhibit further formation.
I have also used a blowlamp and wire brush to remove old paintwork. A note of caution here though, be particularly careful around lugs. Brazed lugs not so bad but soft solder as found on Velocette fork sliders and you can guess what happens next. It goes without saving that you definitely do not use this method on an old petrol tank.
Should you need to do any filling of dents and blemishes, or repairs to holes, now is the time to do them. I wonít recommend a particular product, but do check that whatever you use will be ok with your chosen enamel.
Choose a good quality natural bristle brush. A favourite choice is the Hamiltons Perfection range of brushes. They are not cheap and should be looked after with great care. They may need a certain amount of breaking in. By this I mean, so that they can be used reliably without shedding bristles at a critical moment. Dry brush on some clean brickwork usually serves to remove any loose filaments and then successive coats of undercoating and cleaning will provide you with a reliable brush by the time you come to the finishing coats. Size is another consideration. I use a 2.5Ē brush for petrol tanks and mudguards, a 1Ē brush for the frame, oil tank, tool box etc. and a 0.5Ē brush for very small items.
Brush cleanliness is essential if you want a decent finish. Wash them out after use in the appropriate brush cleaner, then with plenty of washing up liquid and hot water. Then dry wrap the bristles in cling film to keep them free of dust and then hide them from the wife and kids. Do not stand the bush on its bristles as, over time, they will distort.
The biggest challenge facing the coach painter is avoiding dust contamination of the finished work. I have read of some folk resorting to some quite extraordinary measures prior to applying their finishing coat of paint. If stripping off all your kit is for you then fine. For me, I block up all the draught holes in my garage, make sure the floor is clean and then shut the door and walk away. This allows time for any air born dust to settle. When I start painting, the door is opened and closed to cause the minimum disturbance and visitors are not encouraged.
If dust is still a problem, you can create a decent paint booth inside your garage by rigging up several shower curtains to form a cubicle. Its also a good idea to wear cotton overalls, you would be surprised how much fluff you carry around on your clothing. Some water sprinkled on the floor is also good for laying the dust.
A final word of warning. You are now working in a poorly ventilated area so look for any warnings on your chosen paint or for that matter any product and heed the instructions. Your lungs, eyes and skin are rather fundamental to your well-being.
Choice of Paint
In the early days of our hobby, I have read that some restorers used oil based household paints to finish their bikes. Good old Dulux! The criticism at that time was, how could these paints possibly produce a durable finish, on a motorcycle exposed to all weathers. The industry standard then was to stove enamel our motorcycle parts. Well, since then, we have put men on the moon and the Paint Industry has also moved on. Just think of an Oil Rig in the North Sea and consider what paint they use to protect the steelwork. Now I am not suggesting you rush out and buy oil rig paint but modern brush-applied paints have a number of interesting ingredients to help their ease of application and also create a durable finish.
Early on, I used a two pack paint that I mixed in quantities for immediate use. I found that by storing it in the refrigerator overnight after mixing, I could get two days use out of it. It proved difficult to apply as the brush used to leave behind a trail of small bubbles on the surface of an otherwise perfect finish. I eventually solved this problem by gently dry brushing the wet paint which burst the bubbles and left a mirror finish. I painted my Viper this way 25 years ago and it still looks good.
I then moved onto a product called Tecka1oid Coach Enamel manufactured by Croda. The finish was stunning, a deep lustrous black and a lot easier to achieve. The only downside was that it was a bit on the soft side. Later the paint became difficult to obtain and the last I heard was that they had been taken over by Id. I do not know if they still produce it.
Most recently I have used Manor One Pack Polyurethane manufactured by Shipley Paint Ltd. It is described as a quick drying (tack-free in 2 hours) high gloss finish formulated for the commercial transport market which can be mixed in a range of colours. From a practical point of view its applied finish is not quite as glossy as Teckaloid and more in keeping, I feel, with a stove enamel pre-war finish. I would, however, recommend you make your own enquiries with your local industrial paint supplier before you decide on the paint best suited to your needs.
One last note regarding paint. You can apply synthetic coach enamel on top of cellulose but not the other way around. One of lifeís chemical peculiarities!
Your initial objective is to get a sufficient thickness of bare metal primer and undercoat onto the metal that will enable you to rub the paint back, using wet & dry paper, leaving a perfectly flat surface with no brush marks and no bare metal or red oxide paint showing through.
Easy! Well itís not that hard but I did warn you some patience was required. Before you start painting, itís a good idea to make up a few hooks out of scrap wire. Fence wire is just the job. These can be used to hang up virtually all the parts you paint. The only exception is the frame which requires something a bit stronger I screwed two heavy duty hooks into a beam in my garage and hung the frame from these using nylon rope.
Now before you dip the brush into the paint, just plan where you are going to start from and more to the point, how you are going to hold the item to finish it. Elementary stuff but when you come to the finishing coat, you will have had some practice and are less likely to drop the piece on the floor. Choose a suitable etch primer and start your application. For this I would use an old brush, not your new one and apply the paint as evenly as possible. Finish is not too important at this stage.
Load your brush sufficiently so as to have a good reservoir of paint that gives you complete coverage but avoids runs. Itís generally best to brush in long sweeps parallel to the longest face. Finish off with light strokes in one direction only. For the frame I initially paint the tube at right angles to its length and then finish off with light strokes the length of the tube before moving onto the next tube. The final light strokes serve to distribute the paint evenly and minimise any brush marks.
Once the paint has dried thoroughly, inspect for any runs and lightly rub down with a medium grade wet & dry. The red oxide now serves as a useful marker when you rub down the successive layers of undercoat. You will need to apply at least two undercoats rubbing down lightly between each application. For your final flatting of, use the medium grade wet & dry paper used wet. Slightly worn pieces may be better than new as they wonít go through the paint so quickly. Now wash all the residue off and leave the paint to dry.
Remember if you can see brush marks in the undercoat, they will show through the applied top coat. However, donít get too paranoid at this stage. You canít see the back of the oil tank/tool box/inner primary chain case etc. so save your angst for the surfaces that you can see. Also, a blemish that may seem glaring when, say, the tool box lid is in your hand somehow seems far less significant on the assembled motorcycle. So for the sake of your sanity do try to discriminate.
By now your brush is well run-in and you are used to handling bits of bike covered in wet paint, so now onto the finishing coats. A dry warm day is best for your final coats. I prefer to decant a small amount of paint into a clean jam jar rather than work from the open tin. This way, no contamination can get into the tin. Prepare the surface you are about to paint by first wiping over with a Tac Cloth. These cloths are impregnated with a sticky substance that picks up and removes any dust from the surface. Brilliant!
Apply your top coat evenly and quickly. Once the whole surface is covered, run your brush lengthwise to ensure an even application before doing your finishing strokes in the same direction. For the finishing strokes, the weight of the brush is about the only pressure you need apply. You will then see the brush marks disappear as the paint settles to give you a perfectly flat and shiny finish. Do not over-brush the paint, coach enamel does not dry as quickly as cellulose, but does form a skin quite quicky. Hang it up or lay it flat to dry whichever you decided and move onto the next part. I would recommend here that you split your work into smallish batches. This enables you to clean your brush out before it becomes contaminated or overloaded with paint.
Leave to dry for 24 hours then go and admire your work and consider the finish you have achieved. You will almost certainty need at least a second coat. You now need to lightly rub the surface down using a fine wet & dry paper used dry. This serves both as a key for the second coat and a marker to show where you missed with the second coat! Wipe down carefully with your tac cloth and apply another coat as before.
I can not tell you how much paint to apply or how many coats. You will find out with practice. Coach enamel has good tension, but put on too thick a coat and it will either run or sag. Either way you will have to leave the paint to harden over several days before you can rub out the defect.
By now you will have produced a gleaming lustrous finish to be proud of. It will, however, still be quite soft. Leave it to hang for at least a week after which, apply a good quality, soft wax, furniture polish which is non-abrasive and buff it up before putting it somewhere safe awaiting assembly. The paint will continue to age harden for some time, so go easy handling it and do not wrap it in newspaper. The newsprint is mildly acidic and may mark the still tender finish. Itís best left exposed to the air.
Good luck and enjoy yourself.
Vintage Motocycle Club
With kind permission from the editor of their magazine.