Jerrys Old Engines in South Africa

Finishing your etched Brass spec. plate.

I have been asked by a few people how to best finish off an etched brass spec. plate so here are a few recommendations.

I supply the plates unfinished, ie. the etching mask is removed with steel wool and the plate is cut and ground to size - I do not buff or polish the plates - the reason will become clear later. The plate is shiny at this stage but will probably be tarnished by the time it reaches you. I also do not drill holes in the plate.

(Please note that the pictures in this article were mostly taken with a digital camera and electronic flash. As any photographer will understand, this is not the best way to photograph a small shiny object and results in less than perfect pictures. What is needed is a mini studio setup with soft (preferably "bounced") lighting but I'm not in a position to do that right now so just make the best of them as they are :-)

1) Using a power buffing wheel (cloth):
    The use of a power buffing wheel is probably the easiest and most popular method and results in a nice "old" look to the plate but care must be taken not to actually buff away fine detail which can happen very quickly as the power buff actually removes surface brass when too much pressure is applied.

     Note: DO NOT use a power buff if you intend painting the background of the plate - explanation later.

    If you imagine looking at a cross section cutaway of an etched brass plate the top edges of the letters and other raised details on the plate have sharp square corners (edges) when supplied. Vigorous buffing will round these corners off and this is what creates what I described as a nice "old" look. The plate looks like generations of apprentices spent many hours polishing the plate with brass polish and a rag. On many engines this will result in the most authentic looking plate.

    I use a brick of fine buffing soap (I have no idea what this is called in other countries but it is just a block of abrasive impregnated gunk that you hold against the cloth buffing wheel - some of the abrasive transfers to the wheel and helps in the polishing process) to polish the plate and then finish off (by hand) with a liquid brass polish and cloth (and maybe an old toothbrush) to get the final polish (and remove any residue left by the buffing wheel).

    Many people then give the plate a coat of clear varnish or lacquer to prevent it tarnishing. I personally do not do this as I believe that nothing looks as good as a freshly polished piece of brass and prefer to hand polish my plates before going to a show. The choice is yours.

TIP: I'm sure that most of you are experienced in the use of a cloth buffing wheel - this is for those people who are not.
    a) Buff a little at a time and experiment with the amount of pressure you apply - stop often and inspect the result - you do not want to go too far and destroy parts of the plate.
    b) Do not always buff in the same direction - turn the plate around on the wheel to get an even result all round.
    c) Keep a bucket of cold water at hand to dip the plate into - it can get pretty hot and burn your fingers.
    d) Avoid trying to hold the plate in a cloth - safety officers may disagree with this but your fingers work better and are more sensitive especially if you respect them and work carefully. A loose cloth or piece of rag can be caught in a fast spinning buffing wheel and can make spectacular blood coloured patterns all over your workshop. These are difficult to clean when you consider that you will only be able to do it after the stitches are removed and the bloody patterns have had some time to harden :-). Sissys can use gloves!

(I take no responsibility for whatever method you use. I'm not trying to teach you how to use your equipment sensibly - that's your responsibility.)

        This picture of a Wolseley plate shows the result of this method. Notice how the sharp edges ot the letters and other raised parts are "rounded off" or "smoothed" by the buff. The result is a plate that looks old.


Wolseley Brass plate




2) Using steel wool:
    If you do not have a buffing wheel you could just clean the plate with steel wool and then polish by hand using a liquid brass polish and a cloth. I prefer steel wool to sandpaper for this.
    This method results in a "new" looking plate as the "edges" of the letters remain sharp.
    Again, it's your choice to give it a coat of clear varnish or not.

Here is an example of a plate done this way - note that the edges of the letters are still sharp:

Etched Brass plate



3) Painting the background of the Brass Spec. Plate:
    Many of these plates originally had the background painted, usually black but I've seen other colours. Reproducing this is easy and here is my method :

    As I mentioned earlier - DO NOT apply a power buff to the plate if you intend painting the background - you actually want to keep the edges of the letters sharp for this method.

    a) Clean the plate thoroughly using a lacquer thinners and small brush - try to get any dirt out from the valleys between the letters and other detail. You could also use a degreaser or even a good dishwasing liguid instead of the lacquer thinners. Make sure the plate is absolutely dry before the next step.

    b)  Using an ordinary aerosol can (rattle can) give the plate a coat of the desired colour - no primer is necessary. I prefer to use a lacquer paint (Duco) as opposed to an enamel paint but either will work. The lacquer just dries faster and seems to dry "all the way through" whereas the enamel based paints form a skin first and the paint below the skin takes longer to harden. and this causes problems with the next step. Apply a second coat if necessary.

    It is important that the paint is totally dry before the next step. I've had the best results after leaving the paint to dry for up to a week but you can speed it up by drying the paint under a lamp or even on a hot surface outdoors under the sun.

    c)  This step involves using fine sandpaper to remove the paint from the top of the letters and other raised portions of the etched brass plate. There are many methods of doing this and again, I'm sure that most of you are familiar with the process - this is for those of you who have not done it before.

    Many people like to lay the sandpaper on a sheet of glass and then rub the plate over this to remove the paint from only the raised portions.

    My method is slightly different and I prefer to make what I call a "sanding stick". I cut a strip of smooth surfaced material
about 6 mm thick x 150mm long x  25mm wide ("Perspex" or "Plexiglas" in my case but a piece of hardwood or steel would work just as well). I then attach a piece of smooth waterpaper (600 grit minimum if you want a nice finish) to this strip using double sided tape. I use the very thin double sided tape (like "Sellotape") not the foam backed type. You could use an adhesive but be careful not to get any lumps in it - you want to finish with a nice flat sandpaper surface. You could even just wrap the sandpaper around the "stick" and hold it there as you work but I prefer to stick it down.
   
   d) Now lay the etched brass plate on the edge of a flat surface like your workbench (face up) and using the above described "stick of sandpaper"  proceed to sand the paint off the top surface of the letters and other raised portions of the brass plate. This can be done either wet or dry.

    Notice that I said "
lay the etched brass plate on the edge of a flat surface like your workbench". This is beacuse you need to keep the "sanding stick" level and parallel to the plate for the best result. This way your hand (the one that's holding the one end of the stick) can be clear of the table. Avoid the temptation to put more pressure on the front of the "sanding stick" to get a quicker result. Work the sandpaper evenly over the whole area of the plate and the letters and other raised parts of the plate will miraculously start to appear in beautiful polished brass. A warm feeling of satisfaction and achievement will engulf your entire being as this happens and you will have the urge to run and find someone to show your masterpiece to !!
   
    A few tips:
    1)The finer the sandpaper you use - the better will be the end result but will require more patience and energy. Coarser sandpaper strips the paint very quickly but also scratches the brass.
    2) Avoid the (very real) temptation to put extra pressure onto any part of the "sanding stick" - you will scratch the paint below.
    3) If your paint is not dry "right through" the sandpapering will pick up little balls of the softer paint underneath and totally screw everything up.
    3) Once finished you can hand polish with a brass polish and cloth - if your paint is totally dry the brass polish will remove any scuff marks that you got onto the paint by ignoring point 2 above.
    4) Again your choice - you could give it a coat of clear varnish to preserve it for posterity!

Here is an example of a plate done this way - Please excuse the poor quality of the photograph - all that shiny brass is difficult to photograph with an ordinary flash - it needs softer light and I'm too tired right now to set that up!

Le Roi plate




3) Painting the background of the Brass Spec. Plate - Alternative method:
    Another method of painting the background is as used by engravers. I do not recommend this method and will explain later.
    This method entails painting an engraved plate as in steps a) and b) above but instead of waiting for the paint to dry and harden the following is done.

    A disc (or rectangle) of approximately 50mm (2") round or square is cut from something like "Perspex", "Plexiglas", steel or hardwood. This is placed onto a piece of cloth and the corners of the cloth are pulled up and around the back of the disc and twisted tight. This results in the face of the disc being covered with a taut piece of cloth without any creases in it.

    This is then dipped into thinners and dabbed dry just so that the cloth is impregnated with thinners but not "dripping wet".

    This is then rubbed over the plate (as was done with the sandpaper in the previous method) and removes the paint from the high spots.

    Why I do not recommend this method for Etched brass spec. plates:

    1) Engraving (more often than not) consists of the letters being engraved out of the background material. Etching (again more often than not) consists of the background being etched away to leave the letters standing proud of the surface. It can be seen that the actual "surface area" of paint filling the engraved letters is very small compared to the "surface area" of paint filling the background on etched plates.
     Using the above method on engraving works fine because the paint surface area is so small that you cannot see the "wrinkles" and other damage caused to the paint surface by the thinners. When the background is etched and filled with paint the thinners actually damages the paint finish and you do not get that "
warm feeling of satisfaction and achievement that engulfs your entire being" :-)

Here is an example of an engraved plate that would work well using the above method. The letters are engraved away leaving the brass proud. (Obviously this one has not been painted).

Engraved plate


I hope that this page is of use to you - feel free to contact me using the address below if you need more information.

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