Pinholes: Most pinholes are caused by air bubbles, or by dust and other impurities created by exposure to air, storage in paper containers, or storage for too long. Sometimes old and impure enamel makes murky, white spots. Run tests before starting work with any enamel you question. Enamels may be washed to remove impurities but if the enamel is too old and proves to be cloudy, use it for the back only. To remove Pinholes that do occur in any fired enamel, grind them out with an electrically driven diamond or carbide point or by hand with a sharp tool. Holding the enamel under running water, rub the flawed areas with a carborundum stone. Give the areas a final glass brush scrub and rinse. Apply a soft fusing, ground enamel of matching color with Klyr-Fire, dry and fire; it may take several firings to heal the scars. If very shallow pinholes appear in a first coat, the coat may have been too thin. Clean the pre-fired, opaque or transparent surface as usual, apply Klyr-Fire, and dust on an even, thin layer of flux or a transparent. Fire this until smooth. If there are small dark pits, the copper may be exposed by the thin coat; and if there are many, it may be advisable to apply transparents evenly and fire for a trout-skin pattern. Hairline cracks around edges: These may be caused by cooling the enamel too suddenly or by bringing the enamel down too hard when turning it after firing. Some transparents, particularly chartreuse, may crack if they are applied too thickly; these may need counter-enamel. To repair hairline cracks, try re-firing the piece with careful cooling. Shallow cracks on the surface: Work that was too cold when it was placed in the hot kiln - work that was fired when the kiln temperature was too low - or work that was removed from the kiln too soon may develop shallow cracks. Try re-firing, warming the work first. Cracks underneath the top coat: Perhaps incompatible enamels have been used, such as too hard over soft, with unequal fusing. Before using enamels of greatly differing requirements together, run tests if you wish to control results. Cracks with enamel flaking off: The metal was probably not clean enough. Remove the flakes of enamel. Use Carborundum stone on the edges of the bare areas, then brush with a fiber-glass stick under running water; dry the work well. Build up the patches in thin layers of dry enamel held on with sprays of diluted Klyr-Fire. Fire the patches when the layers are quite dry. Flakes sometimes may be replaced, if they are clean on the back, with soft, liquid flux as an adhesive. Dry well before firing. Enamel popping off: This shows the need for counter enamel. Bare spots: The work may have been fired damp, causing steam to move the enamel. Bubbling, crawling and curling back: Such flaws in the enamel may be caused by unclean metal or metal which still has a residue of acid on its surface. Also, if firescale is used as a pattern the top coat of enamel will pull back if the firescale is too thick or if it has not been scrubbed. Blisters: Enamel may blister if impure copper was used. If blisters are glassy, they may have been caused by an impure adhesive, or one brushed on too thickly, resulting in air bubbles. Sometimes there is dust in the adhesive or on the brush. You can try to break the blisters with a sharp tool and mend the enamel as described under Pinholes. Little can be done, however, about blisters caused by impurities in the copper. Dark, thin areas: An enamel was applied unevenly, or fired too long or too high. Sometimes firing on a coat of flux develops a design or the areas may be covered with opaques. Stain under enamel: An uneven coating of adhesive was painted on prior to dusting.Also copper will sometimes stain through fissures that open and close when a higher-fusing transparent enamel is fired over a softer-fusing transparent. Cloudiness: This may be caused by using impure enamels or by under firing transparents. Dark edges: The enamel was too thin - File, polish and reapply enamel to the areas; re-fire.