California Glass Expert Performs a Failure Analysis of Sparkling Liquor Bottle Failures

A bottling line for sparkling drinks was suffering from a high rate of  bottle failures on the bottling line. In addition, several bottles failed on the shelf after bottling. Read Consulting was asked to perform a glass failure analysis to determine the cause of failure of three bottles that had failed "on the shelf". Two of the three bottles were from the same mold cavity, and both failed at the exact same height from the base (2 1/4"). The third bottle failed at 2 1/2" above the base. All three failure origins were the same. All three failures started on the outside of the bottle. All three had "crack arrest lines " near the origin. In addition, All three had no visible mechanical damage to the bottle exterior at the origin.  The presence of the crack arrest line confirms a delayed failure. These factors indicate that the failures are caused by defects caused by the bottle manufacturing process. This is a manufacturing defect that must be corrected by the bottle manufacturer.

Glass Experts Examine Interior Wall of Champagne Bottles

The gas in champagne and most other sparkling wines results from the addition of a small amount of sugar after fermentation has ended. After the sugar addition, bottle is capped. The sugar reacts with remnant yeast and converts to alcohol and carbon dioxide. Because the bottle is sealed, the CO2 gas enters the wine as a dissolved gas. The conversion of the sugar leaves residue particles in the wine that make it cloudy. When the sugar was added a small amount of clay was also added. The clay combines with the fermentation residue and help with precipitation (i.e. drag it out of solution). In a process called "riddling" the particles are encouraged to deposit in the bottle neck just under the cap. This deposit forms a plug that is then frozen and removed before the bottle is corked.

 In this case the particles were attaching themselves to the interior bottle surface (photo upper left). The wine bottling experts at Read Consulting were asked to  determine the cause of the problem. The problem was intermittent, and it had two potential causes. One hypothesis was that there were ridges on the interior wall that were "catching" the particles as they fell toward the cap. This hypothesis is not likely because the bottles are blow molded, and they should have a smoothe interior wall. Another possible cause was a new coating that was being sprayed on the bottle interior. There were horizontal ridges visible on the bottle; however, it was not possible to determine if these ridges were on the interior or exterior wall. The glass experts at Read Consulting cut a panel from the bottle and examined both surfaces microscopically. The ridges that were visible were on the exterior wall; thus, they were not responsible for the "sticking" particles. After the interior spray coating was eliminated, and the problem was resolved. The manufacturing defect is the interior spray caoting.
 

 

Glass Experts Examine Hotel Window Defect

 The glass experts at Read Consulting performed a window defect analysis on defective windows at a hotel. The windows began to appear dirty, and no amount of cleaning could remove the "dirt". When initially installed, the insulated glass (I.G.) windows appeared normal. However, over time they began to appear perpetually dirty. Using a microscope to look through the glass from surface 1, it appeared that surface #2 was heavily scratched. The window was disassembled and surface #2 was examined directly with a microscope. The defect was found to be in the Low-E coating on surface #2. This is a manufacturing defect and not the fault of the building owners. Product liability rests solely with the manufacturer.

Glass Expert Performs Glass Bottle Failure Analysis

Read Consulting failure analysis lab was asked to determine the cause of failure of a small glass cosmetic bottle that had failed in on the filling line as the cap was being tightened. A glass failure analysis was performed using a low power microscope. The root cause of the failure was a chill check on the bottle neck. This damage  occurred during bottle manufacturing. The bottling company will work with the bottle manufacturer to eliminate this manufacturing defect.

CA Glass Expert Performs Bottle Failure Analysis

Overview of Assembled Bottle 8X Mag.

View of Origin on Bottle 40X Mag.

View of Origin on Neck 40X Mag.

California glass expert was asked perform a glass failure analysis on numerous small cosmetic bottles. These bottles all failed where the neck intersected the shoulder of the bottle. Microscopic photos of a representative failure are given above. The glass fracture originates on the outside of the bottle and progresses inward before going around the bottle. These glass failures were found in the filling line, and the bottle manufacturer was notified. The root cause of these failures was determined to be a check (chill check?) in the neck where it intersects the bottle shoulder. This is a manufacturing defect that affects product liability.

Northern California Failure Expert Witness Describes Tubing Failure

An interesting failure of steel tubing was observed when 1 3/4" diameter A513 Type 5 steel tubing was being bent in a tubing bender. In this case the tube was clamped into the bender in the wrong location. At this time the clamp bolt had made an indentation (nick) in the pipe surface. The pipe was released and moved. The "nick" ended up on the tensile surface (i.e. convex side of the bend) during bending. As the tubing was being formed it broke in a ductile manner. A513 Type 5 steel is work hardened and therefore has little ductility, and it cannot survive bending if the surface has been damaged. The appropriate tubing should have been made of C 1020 mild steel. Upper left is a photograph of the nick on the convex side of the bend. The failure is interesting because it is a progressive failure that was caused by non-cyclic stresses (i.e. it is not metal fatigue). In addition, there are faint crack arrest lines that show the progression of the ductile failure. The failure surface almost looks like metal fatigue. This fsailure did not occur when C 1020 tubing was treated in the same manner. This failure was the result of improper material selection. It is not the result of a manufacturing defect.

Failure Analysis of Glass Pot: Visions Cookware

A failure analysis  was performed on a broken 5 quart stove top glass pot. The origin was determined with optical microscopy, and the broken pot was assembled to show how cracking proceeded. The re-assembled pot is shown upside down in the upper left photograph. The failure originated at a preexisting "chip" on the interior at the top rim of the pot. In this case, the the Wallner lines indicated that, initially, the crack grew as a result of bending forces. Although the user had claimed that there was no impact involved in the failure event. The physical evidence indicates that this pot had been "bumped" on the outside near the top rim. It is important to realize that table top glass cook ware is just as fragile as normal annealed glass. It just has a much lower thermal coefficient of expansion. A large pot such as the one in this investigation is heavy, and a minor "bump" to the pot can generate high enough forces to cause failure and potential injury to one holding the pot. It is not unusual to have chips on the inner rim of such a pot due to the fact stainless steel spoons can be used to stir the contents. This failure analysis eliminated the possibility of a product defect or a manufacturing defect.

Porcelain Toilet Tank Failure Analysis

A failure analysis was performed on a toilet tank that had caused water damage to a residence. This failure initiated at a hold down bolt hole. This tank was 14 years old. Originally it was proposed that thus porcelain failure was the result of a manufacturing defect. The root cause failure analysis shows that the tank was subjected to forces that were transfered to the porcelain through the hold down bolts. This toilet tank failed as a result of undue forces. It is not the result of a product defect.

Failure Analysis Expert Examines a Broken Champagne Bottle

A California failure analysis expert witness was asked to perform a glass failure analysis on a champagne bottle that had failed "spotnaeously". Because champagne is under pressure and in glass, there are warnings not to use a cork screw to remove the cork. However, there are cases where the cork is stuck and people will use a tool to extract the cork. The danger is that the tool can damage the inner wall of the bottle neck and initiate a crack that will cause bottle failure. In the present case, a tool was used to pry the cork out and it caused "chatter" damage on the inner wall of the neck very near the top. This damage initiate a crack that finally caused bottle failure. Upper left is a 20X photomicrograph of the damage to the neck inner wall. Upper right is a 20X photomicrograph of the failure origin on the fracture surface. Again, because a champagne bottle is under pressure, one should never use a tool to remove a stubborn cork. There was no manufacturing defect; this bottle failed as a result of handling damage.

Glass Fracture, Califirnia Glass ExpertPerforms Bottle Failure Analysis

California failure analysis expert witness was asked to perform a detailed failure analysis of a broken wine bottle. Glass fractography was used to determine the root cause failure mode. The failure originated at damage caused by the prop on the cork screw. The fact that there were two damage sites on opposite sides of the bottle and that the cork was only partially removed, indicates that the force to remove the cork was excessive. The donward force on the prongs crushed the top of the bottle at two places and initiated a crack that was driven by the force needed to move the cork. This failure was not the result of a bottle manufacturing defect; it was caused by the high forces needed to move the cork and the type of cork screw used. Upper left is a photograph of the two pieces of the bottle neck. Upper right is a 20X photomicrograph of the failure origin and the initial part of the crack. The arrows show the initial travel direction of the crack. Also, visible is the "crush point" at the beginning of the failure.

Glass Expert Examines a Tempered Glass Window Failure

California failure analysis expert uses glass fractography to perform a glass failure analysis on a tempered glass window failure. The glass fracture analysis showed that the window failure was a result of heating the glass in the center. Due to the heat, the center of the window expanded. This created additional tensile stress on the window edges. Although the window edge was ground and chamfered, there was enough residual damage at the edge that the thermal stresses were able to cause window failure. Upper left shows the failure initiation site on the edge of the window. Upper right is a 40X photo micrograph of the origin on one of the fracture surfaces. The glass fracture analysis showed that the glass failure initiated on the window's edge face and propogated inward until the tensile center of the tempered glass window was reached. At this point the residual tempering stresses caused the entire window to self destruct into small "cubic" pieces. This may be a manufacturing defect because of the severity of the edge damage.

Failure Analysis of Failed Plastic Chair

Plastic Failure Analysis Expert performs a failure analysis on a plastic "lawn chair" that collapsed when someone sat in it. The right arm separated from the seat. Upper left is a photograph of the subject chair with the separated leg. Fractography, top center photograph, indicates that the failure was progressive (i.e. a fatigue failure). Examination of exemplar chairs at the site showed identical small cracks where the leg joins the side of the seat. All the chairs examined had this manufacturing defect, and these will eventually show fatigue faikure. This is a product defect (design defect) that must be corrected to improve the performance of the chair. Otherwise, this is a product liability that exposes the manufacturer.

Glass Expert Performs Beer Bottle Failure Analysis

Glass failure analysis expert witness performs a failure analysis on a broken beer bottle. According to the witness the bottle "explosion" occured as the bottle was being set down. The glass expert examined the failed bottle and the failure analysis showed that the bottle failure resulted from damage to tbe knurl on the bottom of the bottle. The bottle must have hit a hard object when being placed down. The upper left photograph is of the re-assembled bottom of the bottle. The crack comes up from the bottom. Thus the origin is contained in the heel of the bottle. Upper right is a 40X photomicrograph of the portion of the heel containing the failure origin. The failure originated at a chip in the knurl on the bottom of the bottle. This is not a manufacturing defect. It is a result of damage caused by the user.

Nickel Sulfide Particles in Tempered Glass

Glass failure analysis expert witness performs a failure analysis on a tempered glass window. The failure was initiated by a nickel sulfide, NiS particle. The glass failure analysis expert was able to retrieve both halves of the failure origin. One side of the failure origin contained the protruding NiS particle. On the other side of the failure origin there was a hole out of which the NiS particle had pulled out when the two halves of the failure origin were separated. Above are two photographs of the two halves of the failure origin retrieved during the failure analysis. These photomicrographs were taken at 100X magnification using Nomarski interference contrast optics. This is a manufacturing defect. The NiS entered the glass during the melting operation.

Glass Expert Performs a Bottle Failure Analysis

A California Glass failure analysis expert witness was asked to examine a failed wine bottle. A portion of the bottle top broke off midway down the cork as the cork was being removed. The root cause failure analysis revealed that the bottle had received a impact to the side. The distinct Wallner lines (see the photomicrograph above) located near the origin demonstrate that the impact was severe. The interaction of the crack front with the vibrations generated by the impact caused very visible Wallner lines. There was no manufacturing defect associated with this failure. When and how the impact occured cannot be determined from this failure analysis.

Glass Expert Analyzes WIndow Damage

Glass failure analysis expert analyzes scratched windows on new construction. There have been numerous occasions where a glass expert has been brought in the determine the cause of window scratching. This is often on new construction that has a stucco exterior. Post construction window claening is critical because of adhered construction materials. Removal of these materials is difficult because of their adhesion. Therefore, cleaning crews should not use blades to remove debris. In many cases abrasive debris such as stucco or cement can be captured by the blade and scratch the glass as the blade is being drawn across the surface. Abrasives can also be captured by dry cloths and pads and can also cause window scratching. The photographs above show the resulting window scratches. Upper left is a sample of cloth related window scratching, and upper right is a sample of metal blade related window scratches. These are window cleaning related and are not manufacturing defects. Only experienced window cleaners should be assigned to clean windows on new construction.

Glass Expert Performs Bottle Failure Analysis

A glass failure expert witness performs a failure analysis on a failed cosmetic bottle. As received, the top of the bottle had broken off. Upper left is a photograph of 'as receceived' failed bottle. Approximately one half of the bottle finish had broken off. Read Consulting performed a glass failure analysis to determine if this failure was a manufacturing defect, or it failed as a result of shipping damage. The upper right photomicrograph is 30X view of the failure origin. The failure initiated at a bruise (small impact damage) on the top of the finish. Three of nine bottles from the same molding cavity also had damage to the top of the finish. In this shipping lot there were over thirty five bottles from other cavities, and none of these showed damage. Thus, the glass failure analysis expert witness believes that this product defect occured during manufacturing. However, both the shipping methods and the manufacturing proceedures will be reviewed for product liability improvement.

GLass Expert Discusses Chill Cracks

Glass failure analysis expert witness discusses a common glass bottle manufacturing defect. After the bottle has been formed it is removed hot from the clam shell tool. If it encounters any localized cooling at this stage, it can form a manufacturing defect called a "chill crack". Thermal shock cause the cooled area to shrink, and this causes localized tensile stresses. This event can create a small crack that can cause later failure of the bottle. Above are two photos of the same chill crack. Upper left is a 20X photomicrograph, and upper right is a 40X photomicrograph. To start, this crack is less than 0.1" long, and it has grown to be approximately 0.7" long. The bottling line has had numerous failures from this lot of bottles, and the cause has been traced back to this type of chill crack.

Cosmetic Bottle Failure Analysis

Glass failure analysis expert witness performs failure analysis on a broken small cosmetic bottle. This bottle failure occured when it was being capped on the line. The objective of the analysis was to determine the cause of the failure and to advise the bottle manufacturer. The bottle broke into two pieces, and these are shown in the upper left photograph. Upper right is a 20X photomicrograph of the failure origin. This failure originated as a result of a "chill crack" which is a manufacturing defect formed when, exiting the clam shell tool, the hot bottle touched an unprotected metal tool. The cold spot created a chill crack that eventually caused the bottle failure. The manufacturer is presently correcting the manufacturing problem. In the meantime, only bottles from another supplier are being used.

Champagne Bottle Glass Failure Analysis

Glass failure expert performed a complete glass failure analysis on numerous champagne bottles that had failed in the riddling process. These bottles are used for riddling and they are made from a large amount of re-cycled glass. Several of these bottle failures initiated at a site that had a piece of unmelted cullet (Note: Cullet is ground glass that is re-melted). The photographs above show one such failure from two vantages. The "lump" of unmelted cullet was larger in diameter than the thickness of the glass (0.120"). The bottle manufactrurer was made aware of the manufacturing process problem and is in the process of fixing it. This is a manufacturing defect that could potentially become a product liability.