ASTM C712:14(R2021) pdf free download – Standard Test Method for Bubbling of One-Part, Elastomeric, Solvent-Release Type Sealants.
4. Significance and Use
4.1 The type and amount of solvent used in these sealants can sometimes give rise to surface bubbling and blistering problems. The substrate used, whether porous or flonporOuS. will also have an effect. Although blistering is often caused by misapplication, this test method is useful in differentiating between a sealant that develops an acceptably smooth surface and one that may have blistering tendencies.
5. Apparatus
5.1 Plates, thin aluminum, approximately 3 in. (76 mm) wide by 5 in. (127 mm) long by 0.012 in. (0.30 mm) thick.
5.2 Blocks, prepare cement mortar, as described in Terminology C719 to the following size: approximately 2 in. (51 mm) wide by 4 in. (102 mm) long by I in. (25 mm) thick.
Note 1—Other substrates such as brick, cast stone, marble, stainless steel. etc., may he specifIed either in place of the standard materials specified in 5.1 and 5.2 or in addition to them.
5.3 Frame, flat, rectangular, of I/j (3.2-mm) steel or brass, with an opening of I in. by 3¾ in. (25 mm by 95 mm) and outside dimensions of approximately 2 in. by 43/4 in. (51 mm by 121 mm).
5.4 Spatula, steel, with knife edge.
5.5 Oven, forced-draft type, having a temperature controlled at 122 ± 3.6 °F (50 ± 2 °C).
6. Test Specimen
6.1 Take the test specimen from a previously unopened container as received from the sealant manufacturer.
7. Procedure
7.1 Prepare three test specimens on each substrate as follows: Center the frame on the test substrate and carefully fill it with compound. avoiding air pockets. Strike off the surface of the compound flush with the frame, to a uniform thickness of ½ in. (3.2 mm). With the spatula, cut all around the outside edge of the compound and lift the frame straight up and off.
7.2 Condition the specimens for 48 h at standard conditions.
7.3 Place the specimens in the oven at 122 ± 3.6 °F (50 ± 2 °C) for 72 h.
7.4 After heat exposure. allow the specimens to cool at
73.4 ± 3.6 °F (23 ± 2 °C) ftr 1 h.
7.5 Examine each specimen for surface gas bubbles and blisters.
8. Report
8. 1 For each substrate, report the total surface area covered by the bubbles or blisters. estimated to the nearest 0.1 in.2 (65 mm2). The area of bubble formation may be estimated by superimposing on the specimen a glass or clear plate Riled into ½-in. (13-mm) squares.