ASTM D cross h Designation: D — 08 Standard Test Methods for Measuring Adhesion by Tape Test1 This standard is issued under the xed designation D ; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon e indicates an editorial change since the last revision or reapproval. This standard has been approved for use by agencies of the Department of Defense. NOTE 1—This test method has been reported being used to measure adhesion of organic coatings on soft substrates for example, wood and plastic.
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However, the method has not been supported by any standard or reliably verified recommendations for its application. Its applicability is overestimated, and its unrestricted use without adequate knowledge and sufficient understanding can lead to non-comparable, non-reproducible and, in many cases, incorrect and severely biased results and assessments.
The main application strategy exploits repeated peeling in the same place on a surface in order to eliminate the effect of the natural decrease in the detached material from the subsurface layers, which might be incorrectly interpreted as a consolidation effect.
There is a discussion of factors influencing the performance of the peeling test method, and examples of peeling measurements on various natural and artificial stones are presented.
In situ testing of the surface cohesion of brittle and quasi-brittle heterogeneous materials suffers from a lack of suitable non-destructive methods.
One of the methods recommended for this purpose is the so-called Scotch Tape test or peeling test. The Scotch Tape test method was originally suggested and used for testing the adhesion of a coating or paint layer to a substrate, and it is defined as a method for evaluating the adhesion of a coating to a substrate.
Pressure - sensitive tape is applied to an area of the coating which is sometimes cross - hatched with scratched lines. The method was probably introduced into the field of conservation for testing the cohesion qualities of historic materials, mainly stone and renders, by Mora and Torraca in the s [ 2 ].
However, no standards or reliably verified recommendations are available for this type of application in conservation practice. Unrestricted use without adequate knowledge and sufficient understanding can lead to non-comparable and non-reproducible as well as in many cases incorrect and severely biased results and assessments.
A study of the basic performance characteristics and features of application of the so-called peeling test method on quasi brittle composites was therefore carried out within the research programme of the STONECORE project. This paper presents an introduction to the peeling test procedures, and proposes recommendations for performing peeling tests on historic stone surfaces and for evaluating the results that are obtained.
There are few systematic literature references on the application of peeling tests in conservation. In most of the works, only a general or superficial description of the measurement procedure has been found, and a detailed description of the peeling test application is mostly missing, e.
In general, the cohesion of a surface layer is roughly assessed by measuring the amount of material stuck to a flexible adhesive tape which was attached to the surface and then removed.
Dei and Baglioni with their collaborators used the method for testing the consolidation effect on a calcareous stone called Pietra di Nanto [ 4 ]. The weight of the piece of Scotch Tape was calculated as an average of 10 pieces. Peeling should be done with a rapid and constant action. Tiano et al. However, the literature results indicated that the results are very dependent on the quality of the adhesive layer, the roughness of the tested surface, the flexural stiffness of the tape, and to a minor extent on the attaching pressure and the speed of detachment [ 6 ].
There are also differences in the valuation of the amount of peeled off material. Some authors use weighing, while others rely on optical evaluation of the tape area covered by the released material, e. They therefore applied a better defined protocol, which is discussed in a later paper for plasters and mortars [ 8 ]. Improved techniques used for testing other than bulk materials, e. The method is based on the Scotch Tape test, and improves it in such a way as to obtain a quantitative result.
For this, a test strip was proposed which contains several regions with adhesives of different strengths. When performing the Scotch Tape test with this test strip, the adhesive can be identified at which adhesion fails and can then be correlated to the adhesive strength.
This approach is hardly applicable for problems of mortar and stone assessment, of course, mainly because the surface roughness is much higher and much more irregular. Unlike in the field of conservation, in surface coating and in the paint and steel production industries peeling tests have been standardized. This system measures the amount of residual dirt on a metal surface. This standardized peeling test is used to check the quality of surfaces, e.
In the second step, the amount of surface residual dirt is evaluated by measuring the reflectivity grey tone. The dirt pulled off by the tape is an indicator of the quality of the metal surface. The measurement is based on the reflectivity of the laminated test strip. For this, a special grey-tone sensor was developed. The grey-tone is determined inside the instrument by a green light source and a photodiode.
In principle, this method could be used for inspecting sufficiently smooth cultural heritage surfaces very fine stone monuments and painted surfaces. This standard is referred to by Daniele et al.
Unfortunately, they do not describe the testing protocol in detail, and it is difficult to assess the mode and correctness of the application. The ASTM D method covers procedures for assessing the adhesion of coating films to metallic substrates by applying and removing pressure-sensitive tape over cuts made in the film.
Naturally, it was developed with metal as a substrate and its application for other substrates has not been tested and validated. However, some hints from the test procedure are worth mentioning here. Permacell 99 tape. Because of the variability in adhesion strength from batch to batch and with time, it is essential that tape from the same batch be used when tests are to be run in different laboratories.
If this is not possible, the test method should be used only for ranking a series of test coatings. The test should be carried out on an area free of blemishes and minor surface imperfections. For tests in the field, ensure that the surface is clean and dry. Extremes of temperature and relative humidity may affect the adhesion of the tape.
On each day of testing, before starting the tests, remove two complete laps of the pressure-sensitive tape from the roll and discard. Place the tape on the surface and smooth it into place with your finger, and then rub firmly with the eraser on the end of a pencil. The colour under the transparent tape is a useful indication of when good contact has been made. Inspect the tested area.
In the commentary on this standard it is stated that there is at the present time no test that can precisely assess the actual physical strength of an adhesive bond. Nevertheless, it is possible to obtain an indication of relative adhesion performance. If the peel angle and the rate vary, the force required to remove the tape can change dramatically. These effects are related, as they reflect certain rheological properties of the backing and the adhesive that are molecular in origin.
This standard suggests four different methods, two of which exploit tape testing. Rub ten times with moderate pressure using the covered eraser, in order to remove all bubbles and prevent scratching.
Remove the tape from the surface and adhere it to the sheet by rubbing with the eraser. Label the specimens using a black china marker. All tapes from other measurements are then cut using a razor to a unified size ready for evaluation. Then the tapes with the peeled off particles are evaluated by reflectance measurements, and the results are rated from 0 to Under diffused light, compare the tape on the black velvet with Photographic Reference Standard No.
Although none of the reported standardized methods was developed for testing mortars and stones, their background, knowledge and experience are exploited in a further recommendation for a peeling test for quasi-brittle materials. The method can be used for making a relative assessment of consolidation effects in individual cases, if an exact methodology and procedure are conserved see the next paragraph.
Examples of such an application are found in the literature, e. Similarly, useful results on stones were achieved with the peeling test on Carrara Marble weathered samples treated with bio-reinforcing agents inducing new calcite precipitation [ 5 ].
A clear reinforcement effect is observed when material removed from treated and untreated weathered marble surfaces is compared Fig. Results of peeling tests on weathered and consolidated Carrara Marble [ 5 ]. The quality of the adhesive layer applied to the tape used for the peeling test is one of the most important parameters influencing the amount of detached material.
Some theoretical considerations are widely discussed in a paper by Chiche et al. They review the fact that in peel tests the applied force necessary for removing a homogeneous adhesive tape from a homogeneous substrate is not constant, and they support the standard approach of removing the impact of force fluctuations in a conventional peel test 7 by statistical treatment of a quantity of measured data. The same approach, i. Thus it is recommended to test the cohesion quality at several tested points over a relatively small area.
It seems to retain this as a recommended testing parameter. The rate effect on the peeling of adhesive tapes from a substrate was also studied in [ 6 ]. Two tapes with different adhesives were tested translucent Scotch 3M and transparent Scotch 3M. However, current standard test methods no longer identify a specific tape.
Differences in the tapes that are used can lead to different results, as small changes in backing stiffness and adhesive rheology cause large changes in the tension area.
The tape test is also operator sensitive. In the standard design it was made as simple as possible to perform, requiring a minimum of specialized equipment and materials that must meet certain specifications. The accuracy and precision depend largely on the ability of the operator to perform the test in a consistent manner.
Key steps that directly reflect the importance of operator skill include the angle and the rate of tape removal. The flatness of the tested surface has a substantial influence on the peeling force, due to variations in the area to which a tape may adhere.
This effect is twofold. Firstly, a larger adhesion area causes a higher probability of touching releasable particles of the surface material. Secondly, the surface of sharp grains protruding from the surface may be so small that the peeling force is not sufficient to peel off individual grains even from rather weak matrices.
In some cases, it is not possible to glue a tape to the surface at all. An application of this kind is described in the next example. Peeling testing is defined as a method for making a quantified assessment of the adhesion of a surface or near-to-surface layer to a substrate. Pressure-sensitive tape is applied to the investigated area and the amount of material detached from the surface after peeling the tape off is measured.
In the conservation field it is assumed that this amount corresponds to the cohesion characteristics of the substrate. Therefore, the peeling test is used for evaluating surface degradation or consolidation effects after strengthening interventions. Various series of tests aimed at studying the basic features of stone when peeling off the surface material have been performed and evaluated at ITAM.
The main doubts about the Scotch Tape method lie in the fact that the loosened particles on the tested surface do not represent the cohesion characteristics of the tested material. Therefore, if we repeat the peeling in the same place we will observe a decrease in the released material and thus we see an apparent consolidation effect, which is, however, false.
Obviously, we have the same problem when checking consolidation treatment effects on degraded historic materials or on deteriorated materials of any age. During the tests, the peeling test is repeated several times on the same surface area.
A brief guide to adhesion testing
Historical Version s - view previous versions of standard. More D Because the substrate and its surface preparation or lack thereof have a drastic effect on the adhesion of coatings, a method to evaluate adhesion of a coating to different substrates or surface treatments, or of different coatings to the same substrate, is of considerable usefulness in the industry. The intra- and inter-laboratory precision of this test method is similar to other test methods for coated substrates for example, Test Method D and Test Method D , and is insensitive to all but large differences in adhesion. Limiting the range of rankings from 0 to 5 reflects the inability of this test method to make fine distinctions between levels of adhesion. Users shall not use intermediate values for ranking adhesion tests within this method.
Nitto (Permacel) P-99 Polyester/Fiber Packaging Tape [Discontinued]
Good adhesion is critical to the integrity and long-term performance of a coating. Poor adhesion can result in failure, corrosion and contamination of surfaces or contents. How can this be achieved quickly and effectively? Testing adhesive integrity can be undertaken using two basic methods. The first is to use a knife to cut through the coating down the substrate in the shape of an X or several parallel cross cuts.