1804 brass finish

Waumbek · Apr 4, 2020

Hi, I'm trying to come up with an appropriate finish for the brass elements in replicating one of Jefferson's initial copy machines circa 1804. The problem is that so many similar gadgets and scientific instruments dating from the period have been polished within an inch of their life over the years. It's consequently very hard to get a sense of their initial appearance. I do not think it was the buffed brass finish we're used to seeing these days. I suspect it may have been what you'd get from a fine steel wool and wax today, but I'm just not sure. Any suggestions would be much appreciated.

rivett608 · Apr 4, 2020

A lot of stuff from that period was polished with pumice which would very similar to fine steel wool. I use those 4 colored foam polishing sticks women use on their fingernails. Then it was lacquered and there is a slight yellowish/amber color to the lacquer, there was a company in the U.K. that still sold it about 10 years ago. I can’t remember the name of it. It is very tricky to apply because you are suppose to warm the brass and brush it on. I think Holtzapffel describes doing this in one of his books.

I collect early scientific instruments and have a number from that period with their original finish. It does have that special look to it that new stuff lacks.

MrStretch · Apr 4, 2020

One can make gold tinted lacquer by making tinctures of tumeric and dragon's blood and mixing them in regular lacquer dissolved in denatured alcohol. Use some gum elemi as well and a very fine sable hair brush.

RCPDesigns · Apr 4, 2020

MrStretch said:
One can make gold tinted lacquer by making tinctures of tumeric and dragon's blood and mixing them in regular lacquer dissolved in denatured alcohol. Use some gum elemi as well and a very fine sable hair brush.

Indeed.. this works well but catching dragons, much less acquiring their blood, has become difficult of late.

Waumbek · Apr 4, 2020

Many thanks

rivett608 said:
A lot of stuff from that period was polished with pumice which would very similar to fine steel wool. I use those 4 colored foam polishing sticks women use on their fingernails. Then it was lacquered and there is a slight yellowish/amber color to the lacquer, there was a company in the U.K. that still sold it about 10 years ago. I can’t remember the name of it. It is very tricky to apply because you are suppose to warm the brass and brush it on. I think Holtzapffel describes doing this in one of his books.

I collect early scientific instruments and have a number from that period with their original finish. It does have that special look to it that new stuff lacks.

Many thanks. It sounds like superfine steel wool wouldn't be that far off then. I might try and fine some pumice. It would also be interesting to try and find foam polishing sticks somewhere about....

Waumbek · Apr 4, 2020

As regards the dragon blood: after working on this project for a number of years its just another thing for the to do list!

ptauser · Apr 4, 2020

I have had some success with household scouring powder (Ajax or Vim here in uk.) For flat surfaces I lay sheet of wet-and -dry emery paper upside down on a flat surface, apply powder with a little water ( to the smooth side) and rub item in a figure of eight movement.
Dave.

L Vanice · Apr 4, 2020

One key to getting good results is to assure you maintain flat surfaces, with no rounding of corners. I used a hand sanding tool with a foam rubber pad and a strip of fine abrasive cloth on a thing I made around 1954. It wrecked an otherwise not too bad effort for an 8th grader. Ever since, I have been careful to put the abrasive paper or cloth on a flat surface, either glued down or loose, depending on the size of the work.

I wonder if some of the old instruments were coated with orange shellac rather than tinted lacquer.

Larry

MrStretch · Apr 5, 2020

The purpose for gold tinted lacquer is to imitate the appearance of cementation brass. Cementation brass became technologically obsolete in the 2nd quarter of the 18th century but was produced throughout the century for furniture mounts and clock spandrels because it looks gold plated.
Speaking of color, clock and instrument makers back in day used something called 'best' brass which was 69/29/1/1 copper/zinc/lead/tin, so yellow like cartridge brass. Modern 'yellow' brasses like 360 are noticeably pink when conpared 70/30 cartridge brass. Besides pouring your own brass, one can use gentle heat from a spirit lamp to turn pink brass yellower.

MrStretch · Apr 5, 2020

For traditional looking finishes it helps to think about the tools that were available as well as the power of traditional hand skills. Scrapers, swiss pattern files, burnishers and leather buffs when used properly will give you square edges and nice looking finishes. Burnishing is especially useful.

enginebill · Apr 5, 2020

rivett608 said:
A lot of stuff from that period was polished with pumice which would very similar to fine steel wool. I use those 4 colored foam polishing sticks women use on their fingernails. Then it was lacquered and there is a slight yellowish/amber color to the lacquer, there was a company in the U.K. that still sold it about 10 years ago. I can’t remember the name of it. It is very tricky to apply because you are suppose to warm the brass and brush it on. I think Holtzapffel describes doing this in one of his books.

I collect early scientific instruments and have a number from that period with their original finish. It does have that special look to it that new stuff lacks.

I would love to see some pictures of the finish on your original instruments.

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