Author Topic: Brush Painting  (Read 3904 times)

Offline fido

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Brush Painting
« on: 11.11. 2006 09:06 »
Brush Painting Technique
As an alternative to spraying, powder coat, stove enamelling etc. motorcycles can be re-finished to a high standard by brush painting, using synthetic enamel paint such as Tekaloid. This paint has an oily consistency and the brush marks disappear as it flows around the workpiece. The method described below is good for restoring elderly bikes with some surface pitting on the tinware.
The choice of primer will depend on the chosen method of preparation. For items that have been blasted I would recommend two pack etch primer, applied with a brush. If some of the old paint is still present you may need to use a different primer as the two pack may react with the previous finish. In such cases you would be safer to use a red oxide primer of the sort stocked by farm supplies shops etc.  This priming should be done as soon as possible after blasting, sanding, paint stripping etc.
Next you need to apply several coats of synthetic enamel filler primer. The number of coats will depend on the amount of pitting but I would suggest a minimum of three coats. As with the primer, this can be brushed on just like normal house paint. You will get brush marks but they will be removed at the next stage. If you are using new brushes for the gloss coats you should initially break them in on the filler primer coats. This is because new brushes tend to initially shed a few bristles, something you don?t want on the final coat of gloss! On a bike I would use a ¾? brush for the bigger items and ½? for mudguard stays, brackets etc.
When you have built up a good thickness of filler primer you come to the labour intensive part of the operation, flatting back. This is done using wet & dry (silicon carbide) paper, used wet. I usually use a washing up bowl with warm water and a dash of washing up liquid. You need to rub down the paintwork until the brush marks and pits disappear. Try not to rub much on the edges of parts or you will quickly get down to bare metal. If you have several parts to flat back you can keep swapping from one to another, letting the first one dry off in between. This is because it can be hard to see brush marks you have missed when the part is wet but they will be obvious as it dries out. When satisfied with the flatting back you need to wash off any residue with more  soapy water.
You are finally ready for the gloss coats and now it is all down to care and cleanliness. When you purchase your synthetic enamel you should also get a pack of tack rags. These are sticky dusters you wipe over the parts to remove dust immediately before you start painting. You also need small containers for paint,  I use yoghurt tubs. NEVER put your paint brush into the main tin of paint as you will contaminate it. Tekaloid covers remarkably well so you will find you can do quite a lot of painting with just a quarter filled yoghurt tub. You will always find your brushes will contain dust so you need to clean them again before you put them into the gloss. I do this using two jam jars filled with paraffin, labelled 1 and 2 , used in that order. The brushes may look clean but you will find the paraffin goes cloudy after a few sessions. Squeeze the excess paraffin off the bristles before painting.
The synthetic enamel must be applied quite thinly or you will get runs. You need to apply the brush lightly to the surface and draw it slowly across the surface in one direction. If you have seen coachlining applied by brush you will know what I mean. You will get a feel for how far to spread the paint. When the brush feels like it won?t glide along the surface but would rather stick to it you know it?s time to refill the brush. You will generally get total coverage with one coat but you need to apply at least two coats. It takes a long time for the paint to dry so your parts need to be left somewhere dust free. I often hang them from wire hooks in an empty wardrobe.
Synthetic enamel is not as hard as cellulose or two pack paint so greater care is required when you re-assemble the bike. Obviously it is easy to touch up though so chips and scratches can be rectified.

Offline a10gf

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Re: Brush Painting
« Reply #1 on: 12.11. 2006 18:30 »
Excellent info, thank you for taking the time to write it all down and make it available.


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Offline dpaddock

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Re: Brush Painting
« Reply #2 on: 30.11. 2006 00:15 »
Darn good stuff, fido!
Another source for info is Radco's tome, "The Vintage Motrorcyclist's Workshop", but it has nothing to add to fido's reply.
'57 Spitfire