This week's focus was on tape removal.
We were given sample sheets made from three different types of paper. Each sheet had eleven types of media drawn on the paper and the same nine tapes applied to them before having been artificially aged in an oven.*
The three papers consisted of: a heavy weight drawing paper, a medium weight writing paper, a low weight mechanical wood pulp paper.
The eleven types of media that had been placed on the papers were:
1. Highlighter
2. water color pencil (blue)
3. ball point pen
4. copy pencil (before aging, the marks looked like that of a graphite pencil. Turned purple after aging)
5. roller pen
6. permanent marker
7. fountain pen
8. color pencil (not water soluble)
9. aniline violet copy pencil
10. graphite pencil
11. fine graphic lining pen
The nine tapes that had been placed on the papers were:
1. framers tape (with an opaque filter)
2. transparent tape with translucent carrier (likely acrylic?)/ a typical clear office tape
3. Filmoplast P90 (Neschen)
4. PH7 - 70 (pH neutral white tape), used in framing
5. Scotch Magic Tape #810 (acrylic adhesive)
6. Crepe tape
7. Scotch removable tape #811
8. Linen tape (actually with cotton) (Neschen)
Some observations could be made about the materials on the paper even before any practical testing was used. Some media was more likely to to bleed into some of the tapes; particularly, the two copy pencils and permanent markers. Some tapes were also more likely to allow media to bleed into them. This, we learned, was more likely to be seen in acrylic adhesives.
After lecture, Monday was spent using a variety of mechanical methods to remove tape carriers from the sample papers. Pure mechanical removal proved difficult all all tapes and papers with the exception of the Scotch removable tape. Various methods of heat application were attempted: heated air pens, small handheld irons, and heating our work spatulas. Of the ones tried, I found that heating my metal spatula on the iron and then working from the center of the tape to the edge worked the best for me. Each paper type had its disadvantages. The thicker drawing paper was sturdy but also soft which allowed for many paper fibers to stick to the tape during removal. The thinner papers were difficult due to the possibility of tearing into the paper substrate during tape removal.
Tuesday was spent looking at removal of the adhesive (as opposed to the carrier). We looked into using cellulose powder and Magic Rub erasers to remove adhesive left on the papers. Solvents and their application methods were also looked into. Some of these methods included solvent chambers**, clay poultices***, and gels****.
Practical Application
Wednesday we were given objects which had tape carriers and adhesive staining on them to treat and test adhesive removal methods on. The objects had water sensitive media on which limited the treatment options. After testing various methods it was found that a clay poultice made with Fuller's Earth and a solvent of 48% ethanol : 52% heptane was the most successful in removing the adhesive stains within the paper.
The Process:
(Safety note: Fuller's Earth is very fine and should not be breathed in. Recommended to use a protective mask with filters. These solvents also require the use of a fume hood and proper ventilation.)
A mixture of Fuller's Earth and the ethanol:heptane solution was mixed in a sealable container (amount of solvent used in the mix also controls how 'wet' the mixture is and creating a drier mix can help prevent tidelines from forming from the treatment)
A poultice was created with these layers: 1. A mylar sheet was placed on the table, 2. A layer of dry Fuller's Earth was placed on the mylar, 3. The object with the area of adhesive was placed on the fuller's earth layer, 4. A layer of wet Fuller's Earth and Solvent mixture was placed on the area with adhesive stain, 5. Place a layer of dry Fuller's Earth over the wet mixture to enclose the adhesive and solvent mixture, 6. Place a mylar sheet on top of this and weigh down the edges with weights.
This poultice was left for 30 minutes before the top mylar was switched out to a mylar sheet with a slit cut into it. This allows the solvent to migrate upwards. Weigh down like before and allow to sit for another 30 minutes. This means the solvent mixture will be in contact with the adhesive for an hour total.
When removing the poultice, the Fuller's Earth will have to be brushed off and the item will need some vacuuming to remove the earth.
This process was sometimes repeated a second time to get better results on some of the adhesive stains.
Positive Results:
The results were very dramatic and the areas where the paper had become transparent from the adhesive became more opaque again after treatment.
Negative Results:
It is impossible to completely remove all residue of the Fuller's Earth from the object afterwards. The fine grains of the clay fill areas of the paper and might be part of the reason why the paper regains its opaque quality after the treatment. The areas which have been treated with the Fuller's Earth has a physically different feel from that of the rest of the paper after the treatment. If the solvent-clay mixture is too wet and the paper is dirty, the process can create tidelines which will have to be treated afterwards.
*parameters for 'aging': ~90C for ~32 hours in a gas oven, a bowl of water was also in the oven to keep up the humidity), alternatively heated and then frozen in freezer.
**solvent cambers: The solvent chambers we used were pre-made for us but they were created using gypsum mixed with the solvent of choice. When used to remove carriers, the carrier should be scored so that the solvents can more evenly interact with the adhesive underneath.
***poultices: different clays were looked at including diatomaceous earth, fuller's earth, attapulgus clay, luvos earth.
****gels: Agar gels were used and soaked in the solvent of choice
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