Martin O'Brien writes:

Groop:

A very good client of mine spilled a cola (Coke or Pepsi) on his
antique (late 19th early 20th cen.) office desk.  The desk has a
leather top.  It's a nice faded green (cross between lime and
olive) with beautiful embossed gilding around the edges.  The
cola has left its mark.  In the area it spilled, it appears to have
changed the color from green to cola (light brown) color.  The color
really seems to have penetrated, almost like a dye would penetrate.

Being an antique, I hate to replace the leather.  Before doing so,
I want to exhaust all possible treatment options.

What are your suggestions for removing the stain.  Might I be
able to refinish the leather?

~~~~~

Martin O'Brien updates:

Groop:

Many thanks to all of you for the wonderful replies to my cola
stained leather top.  After a great phone conversation with Greg
Williams, I began using an airbrush with very thin shellac and
pigments (both Mohawk and Mixol) on some scrap leather.

So far, it shows some promise. I go back to the disaster site this
Monday evening armed with chemicals, airbrush and tiny compressor.

~~~~~

As promised, here are the results:  Thanks to your replies and a

phone consult with Greg Williams, I used wood touch-up

techniques to cover up the offending stain on the leather desk top.

Cola really does a number on leather.  See before and after fotos.
 

I cleaned the leather surface with naptha.  Let the surface dry.  I

then sealed the surface with padded on shellac.  I then used an

airbrush to spray on pigmented color.  I used Mixol (UTC) and

very thin shellac in the airbrush (Paasche VL).    The leather was

green, but the cola stain was dark brown so I had to mix a very

bright green in order to be able to color the leather without

making it look too painted.  I used very little green Mixol, but

lots of white and almost as much yellow.  The resulting color was

a very yellow green.  The color did not match at all in it's liquid

state.  It only matched after it was applied over the brown stain. 

This took me many many tries to get the color just right.  After I

appled the this color layer, I went tapped over color with a

damp shellac pad so as to strike-out or high light certain areas so

that the color was broken looking like the remaining undamaged

(but worn) areas of the leather.  I discovered during the process,

that this leather is very resistant to denatured alcohol.  I was able

to undo/reverse some of my first improper color matches.  I

sealed the color in with shellac applied via pad.
 

In the end, the repair was not invisible, but less noticeable than

before.  I got word the following day that the owner approved

the work so I went back the following nite and applied a coat of

paste wax.  The cleaning crew/maintenance company assured me

that they only use dry microfiber dust cloths with no liquid or

aerosol dusting agents.  So I don't have to worry about the wax

being buggered by another polish.
 

Between 4 separate on-site visits, research/consultation, in-shop

color experimentation on scrap leather and actual on-site work, I

clocked 9 hours and charged for every one of them.  Whether

this large corporate maintenance company decides to pay it or

not is a different story.
 

This was a learning experience and I appreciate Groop's help.

I could not have done it without youse.
 

MartinO
NC