The "Strappo" technique explained here is ideal for frescoes on small bricks,support boards, or studio walls. I have used this method to successfully remove works off of large panels, but I would recommend practicing on throw-away pieces first and small. Professional restorers do use some of these principals when removing historical pieces and transferring them to new a support surface. It is a very complicated process and involves numerous tools and materials of a higher quality not mentioned here. Please do not think this information is a "How To Formula" for removing frescoes of historical value and especially ones of a large size. Removing a fresco which has been painted to the exact diminisions of an entire wall is much more difficult than removing one from a frame or studio wall where you can easily get at all of the edges.It takes teams of skilled professionals and much planning! This method may also remove the sinopia painted on the "Arriccio" or paint which has seeped through to the "Intonicco."Just use the same process as for removing the "Velo." There is a wonderful museum in Pisa which displays the wonderful sinopia found underneath the surfaces or early frescoes.
Plywood or fiberglass
(don't use partical board or cheap wood)
"Vernice Gomma Lacca" (cow bone glue-"Cola Di Bue")shellac varnish.Dry Form.
Water (distilled preferable)
Double Boiler (large lobster pot and a smaller pot)
2" Thin Packing Tape (kind that rips easily.light tan)
"Colla Freddo" (cold glue) boat or marine glue...("Caseina")
2" to 3" House Painting Brush(ample bristles,soft)
2 Large Plastic Mixing Bowl
Cotton Gauze Cloth (#1 Bolt and #2 Bolt)(Like Linen)
Sifter (one which has a canvas bottom to strain liquid materials)
One Dull, Thin Spackling Knife (kind painters use to patch holes or glaze window sills)
Thick Clear Piece Of Plastic (a little bit larger than the fresco)
Sharp Razor Blade
Directions For Strappo:
* Clear a large table to work on. Make sure the work area is clean and free of dust. Prepare as many
things in advance as possible. Be prepared!!!!!
* First select a board that will be used as the support for your fresco. It should be flat and not warped. The size may be slightly larger than the
fresco or the exact dimensions. If you make it a little bit larger, it will mean that the support board and canvas will extend beyond the diminsions of the
fresco. If you use a board to the exact dimension or a hair smaller, any excess canvas and possibly pigment will be trimmed off using a sharp razor blade.
* Cut two identical pieces of cotton gauze which exceed the diminsions on all sides of the fresco by about four to five inches. Do not make it too small!
The cotton gauze used is a #1 and #2. The gauze which has larger openings is used for the "Strappo" and the finer gauze is glued down to the panel support. When finished,one should have two identical pieces of gauze.
One piece from the #1 material and one piece from the #2 material.
* "Colla Di Bue" comes in a dry form. First it must be soaked in water for one hour in a large, plastic mixing bowl. After soaking, strain the mixture
into a second plastic mixing bowl. Use a sifter which has a canvas bottom. The glue may be soaked in a small amount of water. After one hour stir and mix the solution. It should be the consistency of watery syrup (thin and liquidy).Do not know a given ratio...most glue packets come with directions in Italian.Always start on the lesser side and add water until the consistency is achieved. Next remove the mixture and pore it into the double boiler.A large pot is filled with water. Then a second pot is fastened in a way which allows the bottom to rest halfway in the water.The smaller pot will hold the glue as it comes to a boil.
* Brush on the "Colla Di Bue" over the surface of the fresco. Make sure all areas are covered with an ample amount of glue. Place the gauze over the fresco. Stretch it out and try to pull out any wrinkles or bubbled areas (pull on opposite sides of the fabric to do this). Next reapply ample amounts of "Cola Di Bue" on top of the gauze. Make sure there are no dry areas left.Essentially the gauze has glue attaching it to the fresco and glue on top to completely seal it. This provides strength to lift every little piece of pigment or calce. Let it dry in a humid climate for 7 days or in a dry climate for one day.
Transferring The fresco:
* Once the fresco is dry, (use both hands and even pressure) slowly pull the gauze material back. Do not pull hard or at an extreme angel. Be gentle!!!!
After the fresco is off, tape the removed fresco down on a work table. Make sure the canvas side faces down. Take a flat,dull putty knife and slowly scrape off any sand or calce. Be sure to keep the blade at a low angel. Moving it in very small circles prevents pulling up any section of pigment. Work tough spots slowly and from all angels. Tips On Taping.....Lay the
fresco canvas-side down. Carefully place the support board on top of the fresco. Move it until you have the pigment completely covered by the board (like cropping a photo or framing an image). Use this as a guide to tape around the perimeter of the board.Continue with the tape until you reach the outer edges of the canvas.The last pieces of tape should cover 1 inch of your canvas and 1 inch of work table.Now clean the sand and calce off of the fresco (this is literally the backside of the pigment). When finished cleaning, I carefully pull up the fresco and canvas(leave tape attached) and place tape on the reverse side exactly in the same places. This way there is no tackiness to the tape and chance of it sticking to something, during the gluing process.
* Take a second piece of "Fine" cotton gauze and cut it to the same diminsions. Using the support board as a measure again, place sections of tape around the perimeter of the support board...like a frame. Cover the same areas with tape on the reverse side.
* Mix the "Colla Freddo." The mixture is two parts water to one part "Colla Freddo." First fill a plastic mixing bowl with the measured amount of distilled water. Add the "Colla Freddo" and mix with a wisk. Add a bit of lime to the mixture. Once completely dissolved, let the glue stand for Ten Minutes exactly!!! Occasionally stir it...especially if clumps rise to the top of the mixture. It should be the consistency of buttermilk or eggnog. After the ten minutes is up, strain the glue using a canvas based sifter(the canvas on this type of sifter is as thin as nylon pantyhose). This glue is only good for one day!!!!
* (Two people work best and most efficient) Paint the glue on the cleaned pigment-side of the fresco(this is literally the reverse side of the pigment). Get all areas painted with a generous amount of glue. Let this sit for ten minutes, while it gets tacky. Near the five minute mark, paint the board surface with the glue and place over the support board the previously prepared fine cotton gauze canvas. Since this gauze has already been taped, one should be able to line it up within the perimeters of the tape. Immediately paint the top surface of this fine, cotton gauze with the glue in every possible area inside of the taped perimeter (painting top side of gauze.. board is underneath gauze...board,glue,gauze,glue). It is important to stretch out all wrinkles or folds. Do this quickly and with four sets of hands. Remember this is a strong glue and will hold immediately. When I lay this canvas down on the board, I have an assistant hold two corners and myself the others. We then lay it down like we're making a bed. It is important to move quickly and get the wrinkles out. At the ten minute mark, take all four corners of the fresco and place the glued-side down on top of the tacky cotton gauze (the piece which is glued to the board support). Pull any wrinkles out and stretch the fresco to meet the edges of the board evenly. Make sure you frame it on the board quickly and exact because the glue will set up and it is hard to move it more than a few centimeters. Quickly place the plastic on top of the fresco and use the flat part of your hand to smooth out any bubbles. Make sure you push
bubbles to the edge. Make sure to start in the center and work your way out. Do not leave any little area untouched...even if it looks like it is stretched out perfectly. Stretching the fresco tight and getting the air out is essential to achieve a good transfer!!!!!
* Leave the plastic on top of the fresco. Place a board the same size on top of the fresco. On top of this place a heavy weight. It is good to use
something which will displace weight evenly...like a nice wide terra-cotta brick. Sand bags are used on larger works. Let this sit for two hours and
then remove the weight.
* Allow the fresco to dry for one week. Be sure to lay the fresco flat and somewhere it will not be moved.
Completing The Transfer:
* Set up a work area where a good source of hot tap water exists and a good size sink. Have an old house painting brush available (2 1/2" to 3") (make sure bristles are soft and not gunked up), a medium size bowl for hot water, paper towels, and an old white towel (sometimes it is nice to have a dry
towel handy to set the base of the fresco down on)
* Remember too much water will cause glue under the fresco to separate from the board and fresco. Do everything in moderation and focused attention.
* Hold the fresco upright over a sink, bathtub, or shower. Do Not let the fresco rest in the bottom of the sink or area where water collects. This will
cause an area to get water-logged. Take a brush and dip it into a bowl of hot water. Apply amounts of water completely across the top of the fresco (side
to side). Start about one inch below the edge. Work the moisture near the top.Reapply hot water with the brush and work it in circles. You will begin to feel the canvas loosen. Have an assistant try to pick up an edge which is loose and peeled back. Do no force
it up. The canvas will begin to fall on its own. The assistant should hold the canvas and help guide it down. Now that the canvas is moving, keep the
hot water applied to the edge which is just below the loosed canvas...always working across.. side to side. Keep the brush moving in circles and bringing
water as needed. Eventually the whole canvas will slide off. Once the canvas is off, Use a softer brush (4" water color brush) to work isolated spots on
the fresco surface which still have glue immulsion. Gently work directly on the fresco surface; work spots all over the fresco and do not work just one spot at a
time. This will cause a worn mark. Remember the glue dissolves and if you wait and reapply water, the glue will eventually dissolve. After all of the trouble spots are gone, take the entire fresco and give it a rinse in luke warm water. Do this quickly and do not overdo it!!!!!
* note... If you have a small water heater or a low temperature for hot water (a big problem in Italy), a person may want to consider keeping water
at a boil on the stove. Periodically remove a pot full to have ready to replace a luke warm pot of water.
* After the canvas has been removed, allow the fresco to dry upright. Do not leave it in direct sunlight or in an environment where the heat is strong.
Touch Ups and Wax:
* Some areas of the fresco pigment may not have transferred successfully or there may be areas where the artist wishes to add additional information to
the existing pigment. Retouch the fresco using the yoke of an egg and a dash of vinegar (just a little bit). Mix the colors with the yoke and some distilled water if necessary. The colors will dry as they appear when mixed. Let the paints dry for 1/2 an hour to one hour.
* If the fresco is dry, one may apply wax to the surface of the fresco. Use a soft cotton rag when doing this and apply it gently. Be sure to spread it out completely and make sure to get it in all areas. One coat may do or possibly two light coats...depends on how dry the surface is.I personally wait two days before waxing the surface, if I have done in-painting.
* Let the wax-coated fresco dry for at least two hours and then buff it gently with a clean, soft cotton rag.
* Last, trim the excess canvas off carefully. Take the cut right to the very edge of the panel.
* If any of the edges are slightly peeled up, use the "Colla Freddo" to glue down these areas. Cover with plastic and place a small amount of weight on
this surface for a few hours. Be careful not to put too much weight because the fresco pigment is not protected any more and there is only plastic over
it. Textured surfaces transfer and you may snap off a nice raised up section
Building A frame:
* I design my frames before I begin painting the fresco. All of the construction,sanding,staining, or painting is completed ahead of schedule. Once I am ready to place the stretched fresco in its new home, I only have to carefully assemble to pieces around the work. It is not wise to take the chance of dripping or dropping a tool on the surface of your fresco. IT IS VERY DELICATE!!!!. My frames never allow anything to rest on the fresco. The frame pieces rest flush up against the work. A snug fit and anchoring devices from behind work best. I like to have no visible screws or hardware visible.