Removing Adhesive Tape From Sketches Using Eucalyptus Oil

The bulk of this topic has been copied directly from a post on anime-beta created by Sensei. The original can be found here. Given that anime-beta can go through occasional periods of down-time, it may be prudent to duplicate some of the valuable knowledge stored there. This is part of that effort.

WARNING: DO NOT USE THIS PROCESS TO REMOVE TAPE FROM CELS!

You will need:

A bottle of purified, steam-distilled eucalyptus oil.
- You want the straight stuff, not diluted in any way. Small bottles are sold in the aromatherapy sections of health stores, or you can get larger bottles at online sites like Lucky Vitamin for about the same price. Keep in mind that eucalyptus oil is poisonous if swallowed by children and can cause dermatitis if accidentally spilled on the skin in quantity. It might be a good idea to keep the big bottle locked up and use a smaller bottle for your work and refill it periodically.
A supply of cotton swabs.
- Use the kinds with paper sticks as the eucalyptus oil may dissolve the plastic ones.
A box of facial tissues.
- The "hypoallergenic" kind with no added lotion, fragrance, or aloe vera.
A small craft knife, the less sharp the better.
A plain cardboard surface. (Something without anything printed on it.)
A well ventilated space to work with good light.
- A garage with the door open or a well ventilated room (with the windows open) will probably work. Euclyptus oil has a very strong odor.
A stack of sketches with yucky tape on them.
- Some is yuckier than others: frosted tape is often the most stable, yellow-colored tape the most likely to cause trouble. If you hold the sketch up to the light and see that the part covered by tape is more translucent than the rest of the paper, that's an early sign of damage and a warning to get the tape off asap. (It's worth noting that the Library of Congress considers all forms of adhesive tape potentially dangerous to paper collectables, including allegedly acid-free scrapbooker's tape.)

This is the strategy that has been reported to work:

Wash your hands, before and frequently during the process, as dirt and oils from your skin can also cause damage down the road. Some collectors use inexpensive throw-away cotton gloves during this process.
Put the sketch down on the cardboard base, tape side up. Use one of the swabs to dab eucalyptus oil all around the edges of the tape. (Do this for no more than 4 inches of tape at a time, as the oil evaporates quickly).
Turn the sketch over and saturate the paper directly under the tape with the eucalyptus oil. Don’t be cheap – the more you use, the cleaner the tape will come off.
Turn the sketch over again and use the craft knife to get under one end of the tape and slide the blade between the tape and the paper. It should separate from the paper smoothly but reluctantly. When you get enough of the end up, you could grab it with your fingers and peel it the rest of the way. Go slowly and watch out that the paper doesn't start peeling up with the tape. (This happens more often with thin yellow or pink paper than on thicker paper.) If you see a peel starting, stop, turn the sketch over, apply more eucalyptus oil, and start again from the other end. For thin paper, stick with the craft knife and go more slowly.
When the tape is off, soak the swab again in the eucalyptus oil and flood the area where the tape used to be. It's the adhesive, not the tape, that causes the damage, so you want to saturate the area to soften as much of the remaining adhesive as you can. You will often see the adhesive "resist" the oil and leave a dry spot underneath. When you see the oil soaking evenly through the area, that's a sign that you are removing the worst of the glop.
Take a paper tissue and rub the place carefully, looking to see that the adhesive is coming up. It is generally best to wipe in a single direction at a time. When you’re done, the paper should look “flat,” not “shiny.” This can take more time than you think. You will likely need to add more eucalyptus oil after the first effort to get up all of the stickiness. Change tissues regularly.
Let the sketch dry out thoroughly. Overnight is best.
Put the tape, used swab, and tissues in a trash bag and put them outside, unless you're very attached to the smell of eucalyptus.
Bag the sketch to keep now-separate pieces together and prevent any damage that remaining adhesive might cause to sketches stored next to it.

A few warnings:

AGAIN: DO NOT USE THIS PROCESS TO REMOVE TAPE FROM CELS!
Eucalyptus oil does not lift graphite or printed ink on layout paper. It does lift anything that has been photocopied. So if you use it on copy layouts, be very, very cautious and expect some degree of smudging or image loss.
Eucalyptus oil also does lift some colored pencil marks. Use caution if your sketch is done in colored pencil and test an inconspicuous part before going ahead.
Eucalyptus oil will melt/damage plastics. Do not use a plastic container or applicator of any kind.

Other info:

This method has been used successfully to remove tape from watercolor backgrounds and did not shift or lift the colors on the items tested. However, this may not be universally true and caution is recommended in such cases. Also, the eucalyptus oil can move dirt embedded in the paper around the tape as it soaked through the paper, so that when it dries, there are a series of "tide marks" around where it is used. Careful blotting with a cotton ball soaked in the oil may be necessary to redistribute the dirt and soften this "ring around the tape spot." (One library site suggests filling a tray with the solvent and soaking the whole sketch in it to avoid such "tide marks.")'

A note from Sensei (the original author):

This is no more than a record of my personal experience with the process, checked with a number of online librarians' sites dealing with the same issue. For that reason, I'd be happy to be challenged or corrected on any of the procedures mentioned. My only priority, as I've said elsewhere, is to try to ensure that the art objects that I collect remain in at least the same physical condition in which I received them. This is a challenge, as most forms of animation art suffer from what paper collectors refer to as "inherent vice," or the tendency to deteriorate over time due to the very substance from which they are made. Yet they are unique records of a creative process, and once they are defaced, they are defaced for eternity. It's important for serious collectors to confront this issue and find some safe, responsible way to check this deterioration.