Blisters or Bubbles

Other than being used to pack solid dose medication, blisters or bubble packs, as they are often known, may find further applications in pharmaceutical packaging. These may be as a protective overwrap against physical damage, to prevent ingress or egress, to aid display or to act as a tamper-evident/tamper-resistant feature (i.e. packs which are not involved with the solid dosage form). 

Layer separation, blistering or bubbles in container Adhesive layer too cold, did not flow around structure. Adhesive too hot to stick to adjacent layer Adhesive layer cooled too fast Moisture in materials Adjust temperature of adhesive material up or down. Raise mold temperature to prevent fast cool down Dry materials... 

Bleb bleb (1607) n. A blister or bubble on the face of a spinning jet, interrupting the extrusion of the filament. 

Air pockets or bubbles are left on the surface of all concrete. Good vibration and placing techniques will reduce their number but not eliminate them. Many air pockets have a small opening on the surface in relation to their size. Paints will not penetrate into such holes, with the result that air or solvent is trapped and subsequent expansion will cause the coating to blister. In addition, some air pockets are covered with a thin layer of cement that also has no strength and will cause loss of adhesion. 

Materials have been mixed with a high-speed mixer, entrapping air in the resin. After the surface has been troweled in place and finished, air bleeds out as blisters or tiny bubbles. A paddle mixer moving at more than 350 rpm can cause this. 

Establishments primarily engaged in manufacturing unsupported plastics film and sheet, from purchased resins or from resins produced in the same plant. Establishments primarily engaged in manufacturing plastics film and sheet for blister and bubble-formed packaging are classified in Industry 3089. 

Hydrogen reaction embrittlement is a phenomenon in which the hydrogen chemically reacts widi a constituent of the metal to form a new microstructural element or phase such as a hydride or gas bubbles ( blistering ), e.g., methane gas if combined with carbon, or steam if combined widi oxygen. These reactions usually occur at higher temperatures. They result in the formation of blisters or expansions from which cracks may start to weaken the metal. 

Stones opaque particles of rock or batch material embedded in the glass Cords thin string of inhomogeneity Seed or blister elongated bubble (-0.5mm)... 

If the hole is simply coated with solder mask and the solder mask is not developed from the hole, the air trapped in these small holes may expand and create a bubble or blister, or may erupt, exposing the copper in the hole to potentially corrosive chemistries. These holes should be developed cleanly so that they receive the final finish, should be protected before solder mask application with an inert final finish or be completely plugged. 

Blase,/, bubble, bleb blister, vesicle cavity (Metal.) blowhole bladder bladder-shaped vessel, as the body of a retort or still still. Blaae-. blowing, blast, -apparat, m. still blast apparatus, -balg, m. bellows, -lampe, /. blast lamp. 

Fein-arbeit, /. fine or delicate work (Metal.) refining, -aufspaltung, /. fine separation, -bau, m. fine structure, -bewegung, /. (Micros., etc.) slow motion, fine adjustment, feinblasig, a. having minute bubbles or blisters. Fein-blech, n. (Metal.) thin plate, sheet. 

The copper product is known as blister copper because of the appearance of air bubbles in the solidified metal. In the hydrometallurgical process, soluble Cu2+ ions are formed by the action of sulfuric acid on the ores. Then the metal is obtained by reducing these ions in aqueous solution either electrolytically or chemically, by using an inexpensive reducing agent that has a more negative standard potential than that of copper, such as hydrogen or iron (see Section 14.3) ... 

Faults in the Glass.—Notwithstanding a]l the precautions that may he taken, air-bubbles frequently remain, and generally exist in great number when the fining process has been obstructed by too great difficulty of fusion in the glass. They aro technically termed seed, blibe, or blister. 

You may wonder what the source of these bubbles or blisters may be. Blisters are caused by one of two things-water or air. If the substrate is at all porous, it contains air. Or there may be some water inside the concrete, too deep to see. When the hot asphalt is applied, the heat, transmitted into the concrete, causes the air to expand or the water to vaporize. In either case, it tries to escape, and in doing so, causes bubbles. An alternative possible source is the kettle. If a few drops of rain get into the kettle, and the pot tender has not stirred it all out, some foam may have gotten into the pail the mechanic has just used-and as this hot material is spread, a bubble formed. If the pot is stirred with a power mixer, or even vigorously by hand, the surface can trap air which can get into the applied hot asphalt membrane in the same manner. A few random blisters can be repaired without too much trouble-but if there are more than one per square foot this problem should be corrected before proceeding. 

Where the bubbles are caused by air or water in the substrate, another application of hot asphalt will again expand the water or air in the substrate and again cause blisters. Repeated applications will continue to cause blisters as long as water or air is present. It is, therefore, a waste of time to apply more hot material before removing the source of the trouble. The best procedure is to dry the area thoroughly with heat or with a dessicant or both. If time does not permit, and there is not a great deal of moisture or air present, it may be possible to seal the surface with a concrete sealer, such as an amide-hardened epoxy, and then apply the primer and hot asphalt over this. 

Where moisture (or air) in the substrate is so extensive that it appears impossible to eliminate it, or where it is fed from a subsurface source, a satisfactory membrane can sometimes be attained by ignoring the blisters in the first thin layer of hot asphalt, and then laying over this layer a 6 to 12 mil thick pinhole-free, plasticized PVC sheet, lapping all edges 2" or more, and rolling out all wrinkles and air bubbles, then laying another Vs" thick layer of hot asphalt on top of it. The use of visqueen and other stiffer plastic sheets yields mixed results due to poor bond to both asphalt and mortar, and the difficulty of working out air pockets and wrinkles. 

Application of the hot asphalt on a floor (or other horizontal flat surface) is by pouring the material on the surface and spreading it with a squeegee-usually wood, and approximately 18 in. long. Observe workmanship carefully to be certain the mechanic is providing a glassy, smooth and pinhole and bubble (or blister) free surface. If there are bubbles or blisters in the membrane, the job must be stopped until they have been removed and the membrane repaired. (See the section on Asphalt for procedure.)... 

Also check all curing areas (brick joints, monolithics, etc.) for the appearance of bubbles or blisters. An occasional blister is to be expected. If there are many, the matter should be brought at once to the attention of the designer for a decision on action to be taken. 

Part A. Appearing after application arid while the material is still soft and before it has hardened. Bubbles or blisters are small some may break, leaving small indentations... 

Part B. Appearing weeks after cure has taken place. Bubbles or blisters are thick-skinned and usually rather large... 

Alternatively, damage to the outer layers (epicuticle) may be revealed by means Allwbrden reaction [20]. When wool fibres are immersed in chlorine or bromine water, bubbles or blisters known as Allworden sacs are formed on the surface. Damage to the fibre surface may show up by lessening the size of or eliminating altogether, the blisters. This test is particularly useful when damage caused by alkali treatment is severe. 

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