“If the intention is to accurately restore an engine, then the original quality of painting should be followed.” — Peter Rooke
If the decision has been made to paint an engine, the first task is to decide on the type of finish. Depending on the manufacturer of an engine, the standard of paint finish will vary, both in the quality of paint used and the preparation of the castings and parts. Otto engines had a good finish to justify their expense, whereas the cheaper Amanco just had paint applied on rough castings. Lining or pinstriping was also present on some engines, although in some cases, this was for “show” or demonstration engines rather than normal production.
If the intention is to accurately restore an engine, then the original quality of the painting should be followed. To get a flawless finish, a high standard of preparation is essential, particularly the cleaning and priming of the casting. Alternatively, if the engine still has vestiges of paint and has not been ravaged by rust, then it would be entirely appropriate to leave it “as is.” This is very much a personal decision.
Preserving old finish
There are many suggestions for preserving the old finish and patina of an engine. The original manuals mentioned wiping the paintwork down with a lightly oiled rag and this is still the best way.
Do not use WD-40. While this will remove any water, it will not prevent rust; a thin lubricating oil works best or use one of the special anti-rust treatments.
Some people clean the engine and then apply a thin coat of a mixture of 50% boiled linseed oil and 50% mineral spirit. While this gives the engine a luster, it can be particularly difficult to remove, especially from any pitting caused by rust.
Repainting
Whatever the standard of paint finish to be applied, the first step is to thoroughly clean all rust and loose material from the castings and other parts. This can be achieved by glass beading or sanding and scraping. For small delicate parts, electrolysis can be used.
Once the parts are clean and any repairs have been carried out, they should be primed to prevent further rusting, and if you just want a standard finish, then paint can be applied without any further preparation.
For a high-quality finish, the first step is to fill all imperfections in the castings and this can be easily done using a standard epoxy filler. Caution will have to be exercised where parts become extremely hot, e.g. exhaust fittings, when the filler used should be capable of withstanding extreme temperatures. To get a perfect finish, it will take at least two, perhaps more, coats of filler to get all the larger pin holes and indentations relatively smooth, sanding the filler down between each coat.
Care must be taken to match the primer to the top coat so there is no chemical reaction between the paints either when they are applied or over a period of time.
If a brush is being used to apply the top coat or a filler primer, then the finish from the epoxy filler will not have to be perfect. First, apply a thin wash coat of primer, then next apply a filler primer or mix your own. Stir some decorator powder filler in a small container along with some of the primer until it forms a thin, creamy paste. Do not make this paste too thick or it will leave deep brush marks that will then require more sanding down. It is best to keep it thin and apply several coats, building it up to cover the imperfections.
After building up the primer layer, smooth it down with progressively finer wet-and-dry sandpaper until you are satisfied with the finish.
It is best to repaint the engine and all parts separately before assembling the engine. Otherwise, a good paint job will be spoiled if it needs to be stripped later. Paint will have formed a seal between the parts and, in trying to break this seal when disassembling the engine again, there is the danger that some of the paint from the surrounding area will be pulled away. Furthermore, bolt threads and nuts will be painted over, making stripping difficult. It is best to paint parts separately and assemble them once the paint has thoroughly hardened. At this point, give any nuts and bolts a thin coat of paint to match. In the event of any accidents, grazes can be touched up.
Once the primer layer has been applied and finished, the top coat can be painted. This can be sprayed, if you have the equipment or hand brushed. The latter is best as it is simpler for small parts and engines, given the time it takes to clean up equipment, and you generally need two or more spray coats to equal one coat brushed.
The choice of paint is very important. It must be fuel resistant as there is nothing worse than spending hours painting an engine, only to find later that the paint peels when splashed with fuel. Stick to paint that you know works, and take your time to identify the correct shade. The local auto paint shop will usually be most helpful in mixing up paint, sometimes color matching for you.
Unless you have filtered air-breathing equipment, do not spray 2-pack paint as it is extremely toxic.
General rules about painting
It is important that the conditions are completely right for painting, with the ideal temperature around 68 degrees F and relative humidity 60-65% in a well-ventilated area. A 15-degree F drop in temperature can double paint drying time, making the paint more difficult to brush out and giving more time for dust to be attracted. On the other hand, heat or brilliant sunshine can cause blistering and patchiness.
The temperature applies to the casting as well as the air. If the casting has not warmed up to the air temperature, the paint will take longer to dry and will also become thicker and more difficult to brush out.
If there is too much moisture in the atmosphere from mist or condensation, then the paint will be discolored and there will be a loss of gloss.
Ensure your working environment is ready for the task. Allow all dust to settle for several hours and ensure that no dust will be raised while the paint is drying. It is not worth trying to finish sanding the cart while the paint on the engine is drying in the corner! If conditions are right, paint in the evening, then close up the workshop until the morning.
Once satisfied that there is no airborne dust, gently wipe down the engine with a clean cloth, then use a tack cloth to remove all remaining traces of dust. A tack cloth is a coated cloth that holds dust and other particles yet does not leave any residue on the surface to be painted.
Follow the manufacturer’s instructions for the paint to be used. While thinning improves brush ability, dilute it no more than allowed with the correct thinners.
Always use good quality brushes that have been thoroughly cleaned, and first work the bristles by hand to remove all traces of dust and loose bristles.
All cloths for wiping should be clean, as a lot of problems in painting can be traced back to dirt or oil on the cleaning cloth.
Make sure that you have plenty of time to finish the job, as you will always find that if you are working up to a deadline, you always hit a problem then spoil the job while rushing to correct it!
After thoroughly stirring the paint, pour some into a clean container with a lid to use when painting the engine and reseal the original paint can. Working in this way keeps the original paint in pristine condition and reduces the risk of contaminating it with dirt, brush bristles, etc. The lip on the original can is also kept clean, ensuring a good airtight fit to help preserve the paint. Turning the can upside down for a minute after replacing the lid also helps with sealing.
Ensure that the paint is thoroughly dry and hard before touching or moving painted items, and carefully follow the manufacturer’s drying times, allowing extra time if temperatures are low.
After each coat, wipe lightly with 400 grit or finer wet-and-dry sandpaper to remove any imperfections, taking care not to cut through the primer layer and expose bare metal.
After the final coat, any remaining imperfections can be removed with very fine abrasive then polished to a finish. While the paint might appear dry on the surface, it will still be soft underneath and will scratch and mark easily. It is, therefore, best to apply some fine abrasive to remove the major marks, then leave it for a further day or two before removing the last scratches and polishing. It is important that clean dusters are used in this finishing process as it is easy to scratch the surface with one small speck of dirt.
If you have a major blemish or mark, then use 600 grit wet-and-dry paper to smooth it out before touching up with paint. Thin the layer of paint toward the edge of the repaint, applying more than one coat if necessary. When the paint, is thoroughly dry, cut the edges in to blend with the existing paint first using a fine abrasive then polish.
Clean brushes thoroughly after use, and dispose of any dirty thinners and waste cloths so they will not be a fire risk or damage the environment.
Once the paint has dried and hardened, apply a wax polish and buff it up to provide a protective layer. It is easier to do this to the engine casing before assembly.
Caution: While paint might be dry to the touch, it could take several days for it to dry thoroughly and also be fully fuel resistant. Do not rush a paint job.
Lining and pinstriping
Lining out an engine enhances its appearance and adds that extra something to a restoration. However, care must be taken not to overdo it and also keep in mind how the engine might have looked when it left the factory.
While some old photographs show lining, this might not be standard as the engine in question might have been given a high finish for a show or advertising purposes. Generally, production engines like the IHC M had no factory pinstriping as standard.
To pinstripe requires a steady hand and eye, the right brush, and practice. A water-based marker pen, a similar color to the pinstripe, can be used to mark out a line before painting. If the line drawn is not right, it can easily be wiped away with a cloth and then re-drawn. Alternatively, an artists’ colored pencil can be used, a light or dark shade the opposite of the engine paint color.
A professional pinstripe brush has long bristles to hold the paint while completing a line in a single pass. Mix the paint color required and put some on your palette, which can be a sheet of paper from a glossy magazine. Fully load the brush with paint by wiping it across the palette and paint over the line drawn with the marker pen in a single steady stroke. In the case of a flywheel, keep your hand steady and slowly rotate the wheel.
Transfers and decals
To complete the repainting of your engine, any transfers will need to be replaced.
Reproduction transfers are available from specialists for a lot of engines, either made from vinyl-type or water-transferable materials. The vinyl type needs a completely smooth surface to stick to as it will not follow indentations in the surface, unlike water-based transfers.
Water-transfer decals are, as the name suggests, moistened then applied, being finished when dry by applying a coat of clear lacquer or varnish to fix and protect it.
Some decals need to be clear varnished on the underside to fix in position, and then, when the varnish has set, a damp sponge is used to remove a top layer of protecting paper. When thoroughly dry, a top coat of varnish must then be applied to fix it.
It is now also possible to make your own water-transfer decals by using a computer to scan and print an image onto special transfer paper. While good results can be obtained, this method will not provide quite the metallic gold or silver effect of professionally produced transfers.
To make your own water-type transfers, scan the image to be printed into your computer. Next, use a photographic touch-up program such as Photoshop to repair any defects in the image and, if necessary, enhance the colors. After printing on the special paper, allow it to thoroughly dry, normally for 30 minutes. Finally, it needs to be sprayed with a clear acrylic varnish (three or four thin coats) to protect and waterproof the ink.
Carefully cut out the transfer using a craft knife or scissors and soak it in water to apply it in accordance with the instructions. Sometimes it helps to mark out the position where the transfer is to be placed using masking tape and pencil reference lines.
Painting letters
Occasionally, letters or words will need to be painted on the engine or cart. If you have access to a sign writer this is not a problem but there is another way for the rest of us!
Use your computer to print out the word(s) required in the typeface and size you need. Create a stencil by cutting out the letters using a craft knife, taking care to leave tabs to support the center parts of letters like “O.”
Fix the stencil in position with masking tape and then spray or hand brush the required color. The best way is to use a stubby-bristled brush lightly dipped in the paint and applied with a stippling action, angling the brush so that the edge of the template is hit first to force it down against the engine or wood before the paint touches the open part. By lightly charging the brush the possibility of paint runs is diminished, although several coats will be needed.
When enough paint has been applied to reach the correct depth of color, and it has thoroughly dried, peel off the template and touch up the masked areas from the tabs with a small paintbrush.
Paint chips
No matter how careful you are, there will be occasions when your new paint finish is scratched or chipped. With major damage, there might be no option but to sand the damaged area smooth and repaint it.
For minor damage, it might be possible to use a small artist’s paintbrush and fill the scratch or hole with paint. Do this using several layers of paint, not one thick one, so the paint dries better. Apply repeated coats to build the paint up until it is slightly higher than the original paint and leave it to dry thoroughly.
Fold a small piece of 400-grit wet-and-dry paper so that it is triangular and you have three corners. Wet the new paint and then use these pointed ends to sand the new paint until it is almost level with the original. Take care not to sand the original paintwork or you will soon find that you have a bigger area to repaint.
Keep the area to be sanded wet and clean occasionally. If the new paint starts to get soft, it has not cured thoroughly, so leave the repair for a few more days so that it can harden before starting to sand it again.
Sand the paint until it is nearly flush with the original, then change to a finer paper, again taking care not to touch the original paint. Finish off with 1,000-grit wet-and-dry, feathering the edges of the repair into the old paint or use an automobile paint abrasive.
A touch of wax polish will buff up the new dull paint to match the original finish. With this type of repair, the secret is to take your time and not rush it. Allow the paint to dry thoroughly, not just touch dry.
This is an excerpt from Gas Engine Restoration: A Practical Guide for Beginners and Experienced Collectors. Author Peter Rooke is a regular contributor to Gas Engine Magazine and wrote a follow-up book titled More Gas Engine Restoration: Restoration Techniques and Tips for Beginners and Experts.
