DKF – course Copenhagen 01.2005
Cyclododecane – New ideas for application
Leonie Saltzmann – Hans Hangleiter
Introduction
10 years ago E and E Jägers and I first mentioned, the possibilities of using volatile solids for means of conservation application, in public. To my great delight this idea was picked up and advanced by colleagues all over the world.
The basics are well known now so that the function of these substances does not have to be discussed here today.
Especially the abilities in hydrophobizing, sealing and as a protective cover have been discussed in detail and used successfully.
In 1998 (Restauro 7/1998) I mentioned the possibilities in using CCD-laminations as an adhesive connection considering as example the reinstallation of a wall painting stacco.
This property of CCD as a binder, as an adhesive or more precise as an adhesive promoter will be presented by Mrs. Saltzmann and me on examples of some preservation projects.
A general problem is creating a connection of solid CCD to another material. The common adhesives such as adhesive tapes or dispersions do either not attach to CCD at all or they are not reversible without leaving residue. I will do without naming materials unsuitable for this purpose.
Rigid, dimensionally stable laminations and supports
Adhesive promotion
The experience that a two component PU-foam creates an excellently adhesing, very durable connection to CCD is used by us for years for a rigid, dimensionally stable, completely reversible lamination.
The adhesive-pull-strength of a CCD-coating could be tested and proved in two tests.
Promoted by a dense CCD-film a PU-block was to be poured on a brick. The stability of the connection between CCD and PU-foam was to be tested.
Experiment
| BRICK 01 | BRICK 02 |
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| To create conditions as authentic as possible a brick was coated with melted CCD in several layers. |
The second brick was first coated with a single layer of CCD onto which a thin polypropylene fleece was laminated. |
The melted CCD was mixed with 10% petrol ether (boiling range 100-140°C)
After coating the added solvent was given 12 hours to evaporate so that the CCD film could gain maximum strength.
A polystyrene mould was put on the brick and filled with the still liquid PU-foam. A tag was embedded in the foam to be able to hang the brick up for further testing.
BRICK 02
Testing the maximum capacity of the adhesion
The brick was hung up with the PU block so that the CCD layer was bearing the full weight of the brick (3,5kg).
Additional bricks of the same size were attached to the first one by one. At a total of 6 bricks the connection still did not break. The connection was finally forced to break by hand.
A measurable load of 21 kg on an area of a little less than 2dm² was still far from maximum capacity.
Controlling the connection showed, that no PU foam had penetrated the CCD coating and created a direct adhesion between brick and foam.
BRICK 01
Testing the maximum capacity of the adhesion
This brick was also hung up with the PU-block so that the CCD layer was bearing the full weight of the brick (3,5kg).
Additional bricks of the same size were attached to the first one by one. At a total of 12 bricks the connection did not break. The connection was forced down by hand but did not break. Finally the tags could not bear the weight anymore and broke. A measurable load of 42 kg per 2dm² was far from maximum capacity.
Gronau
For a stacco of a painted segment of a half timbered house it was necessary to find a method that would preserve the very sensitive, poudery paint and the intact structure of the surface, with a suitable lamination.
The reason for this stacco done a few years ago was the planned controlled demolition of the house.
The combination of a rigid, dimensionally stable protection of the painted surface with a CCD lamination seemed to be a suitable concept.
01 To avoid an adhesion between lamination layers and the wooden framework the beams were covered with a paste made of wet loam.
02 During the transference the softly bound paint and the top layer of plaster were to be consolidated temporarily. For this reason the front was drained with a saturated solution of CCD in petrol ether (boiling range 100-140°C).
03 The paint layer was laminated with melted cyclododecane (about 80°C) and cotton gauze. 10 % petrol ether was added to the CCD.
04 The reinforced lamination was covered with a second layer of melted CCD. A 12 hour break was held.
05 The dimensionally stability was supposed to be created by the combination of the CCD layers and two different layers of PU-foam.
A wooden frame work was connected to the surrounding framework of the building.
It was supposed to hold the casing for the two-component PU-foam.
06 The casing was made of PU-boards cut into stripes and sealed to the sides with foam rubber. The stacked stripes allowed a controlled, step by step filling of the area. The temperature of the reaction of the two components could be controlled easily.
| 1 loam layer 2 CCD melt 3 soft foam and PU foam 4 foam hard board |
We used an elastic casing out of stripes in order to compensate the end pressure of the foam. If a stiff casing is used and filled in layers each layer of foam will press the casing a little further away from the painting. This will cause damages as the pressure will rise the higher the casing is filled. Plaster and paint will follow and be deformed. The stripes are able to compensate the deformation, as every layer works like the first one no uncontrolled pressure can build up. The foam rubber as a seal to the sides is very easy to handle and connects perfectly to PU-foam.
07 After finishing the lamination on the front, the segment’s filling could be removed from the back. The segment was removed except for the CCD consolidated top layer, so that this part could be taken out easily with the whole rigid lamination.
08 The painted segment was mounted onto a PU support. To avoid contact between PU-foam and the original loam plaster a thin layer of loam was applied.
09 The foam lamination was taken down mechanically. A saw was used to reduce the thick foam.
Afterwards the remaining foam was thinned with an oscillating cutter down to 1 or 2 mm.This thin layer could be penetrated with petrol ether so that the further uncovering of the original surface could be done dissolving the CCD layer.
10 The sublimation of the remaining CCD-residues was increased considerably with a heater.
Further developments
The results of this project were so convincing that the method was used on other objects especially for transmitting wall paintings. As the mechanical removal of the PU block is not very efficient, we will present an interesting development considering the salvage of archeological findings as example.
Heidenheim
Roman wallpainting
In 1992 at the excavation site of a Roman settlement in Heidenheim, fragments of painted roman plaster were found. The fragments seem to belong to a half-timbered wall. In 1992 the plasterpieces were not uncovered, but salvaged in a block excavation divided in 3 pieces, each measuring about 80x120x50 cm.
Between 1992 and 2004 the blocks were stored in the central archeological depot of Baden Württemberg in Rastatt.
The blocks consisted of very hard, dried loam soil with embedded fragments.
The fragments lay in different positions, some with the painted surface showing, others were upside down or standing upright.
The wall that used to carry the plaster probably collapsed completely causing the fragments to spread on the floor. The original position of and the connection between the fragments could not be allocated easily.
Aim and task
Fragments on the blocks’ surfaces showed traces of red and yellow paint. To be able to evaluate the quality and context of the painting the plaster fragments were to be uncovered.
Two problems occurred in this context
First there was a technical problem with the fragile fragments embedded in the much harder loam. A consolidation before uncovering the fragments was not possible. Silic acid esters as a consolidant would have consolidated the soil and dirt surrounding the fragments as well, attaching it permanently to the lime bound plaster of the fragments.
A consolidation with artificial resin would have caused even more difficulties.
The second problem was caused by the loam soil which had to be moistened in order to soften it, otherwise the plaster pieces could not have been moved or handled at all. Water as a solvent would have weakened the fragile fragments even more.
Detailed documentation
Even though there were only traces of colour to be seen in the beginning, a detailed documentation was essential for reconstruction and also for the preservation of the finding. The exact position of the pieces inside the block and the connection to other pieces had to be recorded precisely. It would have cost a great amount of time, if the pieces had to be numbered individually and registered in a plan.
Concept
The blocks were to be taken apart in layers of plaster pieces, to maintain the connection and the precise position of the fragments to one another. This means, that an entire layer of plaster pieces was supposed to be lifted without being divided. Only the surrounding loam was taken away. The size of the area that was to be salvaged was only restricted by the endurance of the used materials and the technical possibilities to handle big measures and weights.
After the salvage, the following options were necessary:
All fragments had to be preserved in the finding position without structural changes. The salvaged layer had to be placed on the working table in the restorers lab.
All fragments had to be cleaned and consolidated in the finding position. The salvaged layer had to be placed on the working table in the restorers lab.
The concept for the salvage was based on the following details
01 Softening the hard loam without using water.
Due to a discovery still lacking a scientific explanation it is possible to soften the dried loam with alcohol. Pure ethanol makes the loam soil soft and crumbly so it can be reduced mechanically. Unlike water it does not make the clay sticky and smeary. Using other solvents such as acetone or petrol ether (boiling range 100-140°C) for moistening does not show comparable results. Several tests were made by adding water to the ethanol. The clay will still soften when water is added but it will become stickier as more water is added. The low percentage of water contained in spirit had no notable effect and could therefore be tolerated.
02 Producing a non permanent film of cyclododecane as an adhesive promoter.
CCD will reach best adhesion if it is spread evenly on the object, slightly penetrating the surface. To create an even coating it is essential to use CCD at a high temperature (80°C) (the cooler the material gets the less it penetrates). Adding about 10% of petrol ether (boiling range 100-140°C) makes it much easier to apply cyclododecane as the material spreads better and does not harden as fast.
Due to the solvent added, the cold and hardened CCD-coating is rather soft. It will harden as the solvent evaporates. Therefore it is necessary to wait at least 12 hours for full firmness.
Dense fabric as reinforcement is unsuitable or at least very difficult to use. Experience has shown that the same adhesive tensile strength is much harder to create with a dense fabric compared to a loosely woven one. Best results were made with cotton gauze (one mesh measuring about 1mm), other suitable materials are fleeces made of polyethylene and polyamide, or light cotton fabric. It is essential to work with very hot CCD!
03 Create a drainage system, to enable the complete dissolving of the CCD-connection layer between the PU-foam and the object.
The CCD cover is only for an expanded salvage of fragments. For further work, the connection had to be solved as fast as possible. To enable the solvent to dissolve large areas from the inside, a drainage system was built in during the lamination of the object. About every 10 cm drain channels were build in between two layers of reinforcing fabric of the lamination.
04 Creating a dimensionally stable mounting block of PU-foam to connect the fragments with the CCD-lamination.
We used a two component Polyurethane foam with sealed porosity and a specific weight of 50kg/m³. This material has sufficient physical properties such as steadfastness and dimentional stability. Depending on size and thickness of the PU-block additional armoring was necessary. The armoring was helpful to stabilize and to attach girths for lifting the PU-mounting block. Due to the combination of PU-foam and armoring it is possible to salvage very large areas in one block.
In this step the ability to attach to CCD and the resistance to cyclic hydrocarbons of the PU-foam were essential.
As the reaction of the two PU-components is exothermal it was important to work with small amounts, letting each amount cool down before the next one was added. This helped to keep the temperature below 60°C, below the melting point of cyclododecane.
As an alternative to PU-foam, two component Epoxy resin foam could also be used. (this product was introduced to us by David Singleton and Eric Miller). Our tests showed an excellent adhesion of this material to CCD.
05 Fast dissolving of the CCD adhesive promoter between plaster fragments and PU-mounting block in a bath of solvent.
This method aimed on the one hand on salvaging fragments in their original position and on the other hand returning them to their original condition in a short time and with little effort. This was the reason the CCD film was dissolved in a solvent bath. This bath only split the connection between fragments and foam but did not remove the CCD completely from the fragments. Depending on the concentration of cyclododecane in the bath and the porosity of the salvaged object, the residue can have consolidating effects. The sublimation of the residue took place in a few days, depending on the temperature. The time for sublimation should be taken into consideration. To keep the consolidating effect as little as possible the solvent could be changed once or twice. When dissolving the CCD in the bath, temperature had to be controlled. At 20°C one part CCD solves in one part petrol ether (boiling range 100-140°C). At 10°C solubilty is much lower and the compensation of concentration through the drainage channel system slows down.
Implementation
Large connected fragments were only visible from the back. All loose material was removed and loose fragments covering the surface were numbered, photographed, registered in a plan and removed.
Softening the loam
The loam soil was soaked with ethanol. Enough alcohol was poured on the surface to provide several centimeters of soil to be moistened thoroughly. This was essential for the following steps, as the connection between loam and fragment had to split easily during the salvage.
Uncovering the object
The loam had to be removed from the fragment’s surface as far as possible. In heavily soiled areas the loam was reduced with a spatula and afterwards taken of with a stiff brush.
Drying of the surface
All fragments that were to be lifted had to be dried with a heat gun before applying the cyclododecane, because the CCD would not connect to a wet surface.
Picking the area and constructing a frame
The area that was to be salvaged was fenced with a wooden frame. The fence should keep CCD and PU-foam from soiling the surrounding area.
Choosing the fragments for salvaging
Before applying the CCD lamination, all fragments that were not to be lifted had to be covered with sand or “Perlite”, produced from a naturally occurring siliceous rock, that when heated to a suitable point in its softening range, it expands from four to twenty times its original volume.
Lamination with gauze reinforcement
The fragments were covered with stripes of cotton gauze on which molten CCD was brushed carefully. This procedure was done twice. 10 % petrol ether (boiling range 100-140°C) was added to the melted CCD to make it supple. The CCD had to be heated to about 80°C in a water bath. The gauze had to be attached firmly to the surface of the fragments following the contours carefully.
The gauze was attached thoroughly to the wooden frame.
Installation of the drainage channel system
A mat of randomly oriented fierr (thickness 1cm) was cut into stripes of about 2 cm and spread on the CCD-lamination evenly. If necessary the stripes were fixed temporarily with CCD and gauze. Care had to be taken, that the stripes built channels from one side to the other being open towards the frame.
Lamination with cotton fabric
On top of the drainage channel system a light cotton fabric (more dense than the gauze) was applied. This worked as a barrier layer between foam and object. This layer had to be applied with great care. Closing all holes to the frame or the layers below was essential for the success of the salvation.
Additonal CCD-coating
A second coating of CCD was added to keep any foam from penetrating towards the plaster fragments. The CCD should not be as hot for this coating, as it builds up a thicker film when used with lower temperature.
Drying
It was necessary to let the lamination rest for about 12 hours so that the coating could gain its full strength.
Creating a PU mounting block with a wooden reeinforcement
The inside of the frame was filled with PU-foam in several portions. For reinforcement and to simplify the lifting, a wooden grid with straps was embedded in the foam. After the foam had hardened it was leveled on top to make it stand secure when turned.
Lift and turn
The complete package could be lifted from the block easily, turned and even be transported. The chosen fragments (and no others) were attached to it securely. The loam on and between the fragments was crumbly and could be brushed of easily.
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Uncovering of the second layer
After lifting the first layer, the loam underneath was still drained with alcohol. This circumstance simplified the uncovering of the second layer of plaster fragments. The moist and crumbly loam could be brushed of. When it was necessary to dig deeper some more alcohol was added.
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Preperation and salvage of the next layers.
From each of the three blocks two connected layers of fragments could be salvaged. Underneath large pieces of a lime-plaster-floor were found.
Cleaning of the painted surface
Before consolidating the fragments the surface had to be cleaned from the remaining loam and dirt. It was helpful having the fragments fixed temporarily on the PU-block.
Consolidation of the plaster
A partial consolidation of the plaster was carried out. As the fragment were still attached to the PU-foam block with CCD it was important to pick a material which would not interfere with PU-foam or CCD. In this case the crumbly edges were stabilized with syton X30. After drying, the sensitive parts were consolidated with silic acid ester Motema 28 from Fa. Interacryl.
Dissolving the CCD
Preparation
The CCD layers had to be dissolved in a bath of petrol ether (boiling range 100-140°C). Depending on, which side of the fragments should be visible, a counter mould had to be made. For the mould the back of the fragments was covered with two layers of polyethylene foil. Undercutting parts were filled between the two foil layers. Wet cotton was very helpful here. On the foil a second PU-block was created. The block was taken off, cut even and replaced so that the package could be turned.
Solvent bath
The drainage system had to be controlled and cut free.
A bath was made of wood and polyethylene foil around the block. The package was weighed down with a bag of sand to keep it from floating and then covered with solvent. It took about 10 hours for the CCD to dissolve completely. It was necessary to let the solvent out of the bath before taking of the weight.
Uncovering
The package could be lifted and the covering PU-mould and, depending on which side was up, the fabric could be taken off. After the solvent had evaporated, white CCD residue covered the fragments but it sublimated fast.
Burial complex of Quin Shihuang in Lintong, China
Salvage concept for stone armor
We developed this concept during summer 2003 for the Chinese – German partnership project between the Museum of the Terracotta Warriors and Horses in Lintong and the Bavarian State Department of Historical Monuments in Munich. Each of the original sets of stone armor is made from about 600 individual small limestone plates which are connected to one another with cast bronze wires.
The task was the salvaging of an armor for study and presentation reasons. The development of our concept was performed with two mock-ups, the first done in our lab and the second one in Munich on a copy of an original piece.
This concept has two essentials:
First the options for big area salvaging in one piece and secondly the option to reverse all bindings necessary for the salvaging process, without leaving residues, in order to continue conservation shortly after the salvage.
In 2004 the colleagues from the Munich lab performed the concept in China on an original fragment of armor. The procedure was very successful. Even the fragile cast bronze wires were salvaged without taking any damage.
Details of this Project will be published soon by Sandra Bucher (Bavarian State Department of Historical Monuments in Munich)
Volatile lamination with controlable sublimation
Laminations with CCD have been very successful in situations in which a completely reversible temporary covering for only a short period of time was necessary. But so far it had been a problem to secure an object with an reversible lamination for a longer time.
The sublimation of CCD can be stopped by a vapor-sealed covering.
This problem concerns especially large objects like wall paintings and architecture.
In summer 2003 we were commissioned with the restoration of a wall painting on the facade of the Orangerie in Bronnbach –Main Tauber Kreis.
For the preservation of the painting measuring about 100m² a temporary lamination was necessary to stabilize the plaster during the entire construction work on the wooden construction. It was essential to stabilize the thin fragile plaster and to keep the painting from being soiled. For the construction work, a time of 6 months was planned. (Kaschierung 01, Kaschierung 02)
The facade of the building faces south, it is crowned with a painting of 22m length and 4,3m height. The picture was painted in lime technique on a lime bound plaster. To connect the plaster to the wooden construction of the south facade a net of split twigs was attached. The wooden construction carrying the painted plaster was fixed on the buildings roof framing. Water and wood worm had damaged the entire construction in such extend that work on the roof and the back of the picture were inevitable.
The painting had to be secured from the front with a CCD lamination and a supportive device for the time of construction. As the work was going to need at least 6 months the lamination had to be covered.
To obtain a durable lamination on the south facade, a vapor sealed layer had to be added to the CCD-lamination.
Requirements for the lamination
The CCD-layer secures and protects the sensitive and weakly bound surface of the painting
This layer had to be covered by a vapor-stopping foil to prevent the CCD from evaporating before time.
The adhesive should not get its binding by evaporation of the solvents, as the CCD-layer is mostly vapor-sealed as well.
The cover has to be taken off easily without damaging the painting below.
The choice of adhesive
The adhesive used was the same two-component-PU-foam used on other objects as dimensionally stable mounting block. Even though the properties of the foam were not 100% suitable for this use, we chose it because it was at this point the only material known to us that attached to CCD without containing solvents.
Components of the lamination
First a dense film of CCD was applicated onto the painting. For this film 10% petrol ether (boiling range 100-140°C) (boiling range 100-140°C) were added to the melted material. This first layer worked as a barrier film.
Next a fleece reinforcement was fixed with a thin CCD melt. The fleece was made of polypropylene (used for covering plants in winter, can be bought in DIY superstore) To keep this CCD-layer rather thin and the connection weak, much solvent, about 30%, was added. It was essential to have the fleece connected only slightly as it was to be taken down with PU-adhesive and foil after construction was done. Before continuing with the next layer the solvent had to have 12 hours time to evaporate.
The top layer was to be made of tin foil. It was attached to the CCD with two-component-PU-foam. The soft material was spread thin on pieces of foil with a spatula. The foil was then pressed on the prepared CCD lamination.
After construction was finished the top two layers could be removed. Fleece could be taken down with PU-foam and tin foil.
Difficulties with the method
The operation was very successful, the CCD secured the painting for the entire construction time and evaporated completely after the top layers were taken down.
The method was connected with difficulties anyway. Applying the foam to the aluminum segments caused several problems. First of all the foam hardened rapidly only leaving a few minutes for application. This time could be stretched a little by cooling the two components and the mixture of both with iced water.
Secondly it was necessary to spread the material thin and evenly on the foil. Areas with a thick layer of foam would have increased in volume and turned very stiff. Removing these areas after construction could have lead to a loss of paint. The thin and even spreading of foam was especially hard on warm days.
Taking off the fleece, foam and foil worked perfectly in most areas. In some parts though several difficulties occurred. There were parts with a very weak layer of paint underneath, here the package could not be torn down but had to be drained with petrol ether (boiling range 100-140°C) to solute the connecting CCD after peeling off the tin foil.
Another problem was caused by the fleece layer which in some areas would not come off as easily as planned. Fibers and sometimes little pieces of foam remained on the lower CCD layer and had to be removed with petrol ether (boiling range 100-140°C) as well. This problem could have been caused by adding the solvent to a large amount of CCD and working with it for a long time. The solvent evaporated from the melted material causing the concentration of CCD to rise over time. To avoid this problem only small amounts of melted CCD should be mixed with the solvent.
Resumee
The results of the method were satisfying as we cant thik of a more gentle protective lamination than one made of CCD at this point. Inspite the good results the covering of the CCD with tin foil is very complicated and should be simplified.
Further testing
After the project in Bronnbach was finished we continued the search for a more suitable adhesive. Two very interesting alternatives were found.
Honey as adhesive for the vapor seal
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In one of our tests we tried honey as adhesive. The adhesive power is strong enough to attach tin foil to CCD. The honey stays in it wet and sticky state during the entire time the lamination is covered.
One problem occured when we heated our testing area to increase the sublimation of the surrounding CCD. The honey melted and ran out under the foil. This problem was solved by adding highly disperse silic acid (Aerosil) to the heated honey. The honey does not turn liquid at temperatures of 60°C (melting point of CCD).
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A cover attached with honey has several advantages compared to one attached with PU-foam.
Honey is cheap, can be bought everywhere and is completely harmless. It is much easier to work with as it does not consist of two components that will harden. The foil can be taken of the lamination easily and remains can be washed of with water. To avoid soiling the surrounding areas CCD spray should be used to seal them before the tin foil is taken off.
To find out if the honey covered lamination can be used on the outside of buildings we attached tin foil with the honey aerosil mixture to a car. After one hour on the autobahn in rain with a speed of about 140kmh the attached foil was still in good conditon on the car.
Elastic PU-coating as adhesive for the vapor seal
Other tests were made with an elastic 2-component-PU-material (PU-coating). This material builds up a clear, resistant and elastic film which adheres well to solid CCD.
In the test following aspects had to be tested:
The connection of the PU-coating to vorious CCD-surfaces
The vapor sealing properties of the PU-coating itself
Methods and modes of application
To prove these properties following Tests were chosen:
01 Adhesion of tin foil directly to the dense CCD-layer
02 Adhesion of tin foil on a loosly bound fleece layer
03 Adhesion of tin foil on a loosly bound gauze layer
(The loosly bound layers contain 3parts of petrol ether on 7 parts CCD)04 Coating with PU-coating directly to the dense CCD-layer
05 Adhesion of polypropylen fleece with PU-coating to the dense CCD-layer
06 Adhesion of cotton gauze with PU-coating to the dense CCD-layer
Method of application
Test boards
As test surface we used boards of fiber enforced concrete (Fermacell) about 10mm thick. The boards take up water well, comparable to lime bound plaster.
The layers of CCD were comparable to those used in the example described above.
Boards with a base layer without reeinforcement:
Hot melted CCD was brushed on the board three times with about 10% of petrol ether (as above) added
Boards with additional fleece reeinforcement on the base layer:
Thin Polypropylenfleece was attached to the base layer with diluted CCD (3parts of petrol ether to 7 parts of CCD)
Boards with additional gauze reeinforcement on the base layer:
Cotton gauze was attached to the base layer with diluted CCD (3parts of petrol ether to 7 parts of CCD)
Coating the tin foil with PU-coating
We colored component A with pigments to make possible residue on the CCD visible.
The PU-coating was mixed, spread evenly on the piece of tin foil with a plastic spatula and attached to the CCD film. Coating fleece and cotton gauze was done the same way. The PU-coating was spread on the CCD layer with the spatula as well.
Results of the testing
Right after the adhesive had hardened first judgements were made.
After a few hours of waiting needed for the material to harden (the time nescessary depends on the temperature, the warmer the faster) the tests could be removed.
It was easy to take off the package of PU coating and tin foil from the dense base layer, little residue, very well visible due to the pigment added, remained on the CCD.
Taking off coating and tin foil from the fleece and gauze lamination is not quite as easy as the coating penetrates the porous CCD layer and connects mechanically.
Colored residue remains on the surface. If the fleece / gauze layer was taken of as well, it came down easily and not a trace of PU coating could be found on the CCD-base-layer underneath. It makes no difference if fleece or gauze are used.
After sublimation of the uncovered cyclododecan another judgement was made. Sublimation was enhanced by high temperatures close to a heater.
Coatings without tin foil
All PU-coatings not covered with tin foil came off by themselves after a few days. This showed clearly that CCD can volatize through the PU-layer, wich means that CCD vapor can go through this coating. It could also be seen that the residue of colored PU-coating mentioned above fell off as well or could be removed easily with a vacuum cleaner.
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Coatings with tin foil
After the CCD had sublimed completely from the uncovered areas, no changes could be seen in the CCD lamination under the coated areas. As far as visible the PU-vapor-seal worked perfectly.
Further testing
The tests described were done with a fast hardening PU-material, further test were made with a slower working type. The handling of this material is easier and led to new ways of application.
The tin foil pieces were coated with the colored material and the start of the reaction was waited for. From this point on the coating stayed adhesive enough for a good connection fo about an hour. The test made this way could be removed after a day easily without leaving any residue.
About final results we will in form soon.
CCD-fleece
In a room fitted whith large scale wall paintings climate measurements were to be made.
This included measuring the surface temperatures in the painted areas.
The sensors had to be attached whith direct contact to the paintings. CCD was the prefered adhesive due to its known abilities. Our reqierments made it hard for us to use CCD in the tradional form of application. On the one hand CCD is not suitable for connecting two items and on the other hand only very few adhesives attach to CCD-films. (See controlable lamination).
To enable us to use CCD for attaching items to a wall we created adhesive CCD-patch which attaches when heated. This patch is made of a fleece (cotton or synthetics) drained in CCD and laminated whith aluminium. Instead of tinfoil a paper laminated whith aluminum was used because it sticks better to cyclododecan.
The prepared fleece patch can be cut into pieces and be attached to the wall by heating it whith a hot iron or a heatable putty knife. It is helpful using a hostaphan foil when ironing and reducing CCD residue on the aluminium mechanically.
A thin layer of polystyrene can be attached to the aluminium surface with 2 sided tape which woks as a separating layer. Items such as measuring unit can be fixed on the patch with 2 sided tape. For the sensor the CCD patch can be used like adhesive tape (see picture on top right).
To remove the items without risk and to take the sublimation blocker off the patch, the polystyrene layer can be diveded with a little saw. The remaining polystyrene and the laminated paper can be pulled of the CCD drained patch. As soon as the cyclododecan is in contact whith air the sublimation starts.
After a few weeks the fleece patch would fall off by itself. If the process should be quickened the fleece can be drained whith benzine until it comes off easily.
The CCD-patch can also be used as a temporary label, i.e. to labele plaster fragments temporarily. Another possible use for CCD patches could be for lables, as they are used to create corrected plans of buildings. The lables used today are very often attached with glue, remaining on historic buildings in nasty spots for many years.
For this use CCD has the great advantage of attaching even on crumbly and uneven surfaces perfectly.
