Full Answer
What is pinholing in coatings?
Pin-holing refers to a small, sunken area that forms on a coating film after a bubble ruptures. Pinholes are typically larger and less abundant across a coating's surface than solvent pops. They are tiny holes or groups of holes in the finish, or in putty or primer which are the result of: Trapped solvents. Air. Moisture.
What does pinhole mean?
- Definition from Corrosionpedia Definition - What does Pinhole mean? A pinhole is a pore-like penetration that is present in paints and coatings due to the entrapment of moisture, air, solvents or other fluids.
What is a pinhole occluder?
A pinhole occluder is an opaque disk with one or more small holes through it, used by ophthalmologists, orthoptists and optometrists to test visual acuity. The occluder is a simple way to focus light, as in a pinhole camera, temporarily removing the effects of refractive errors such as myopia.
What is pinhole corrosion?
What Does Pinhole Mean? A pinhole is a pore-like penetration that is present in paints and coatings due to the entrapment of moisture, air, solvents or other fluids. The presence of pinholes increases the corrosion rate experienced on a surface due to the moisture pockets that cause crevice corrosion, pitting and increased redox reactions.
What Does Pin-Holing Mean?
What causes pin holes in epoxy?
Can you inspect a surface before applying topcoat?
What if you just cannot solve a pinhole problem?
The cause is likely a combination of thick glaze layer and gas-producing particles in the body. Bodies containing ball clays and bentonites often have particles in the +150 and even +100 mesh sizes. The presence of such particles is often sporadic, thus it is possible to produce defect-free ware for a time. But at some point problems will be encountered. Companies in large production need to have fast firing schedules, so they either have to filter press or wet process these bodies to remove the particles. Or, they need to switch to more expensive bodies containing only kaolins and highly processed plasticizers. But potters have the freedom to use drop-and-hold or slow-cool firing schedules, that single factor can solve even serious pinholing issues.
How can you best tell if a base glaze is prone to pinholing with your body?
Testing for pinholes and dimples is often best done using a transparent glaze over a large surface and looking at the surface in the light. In this case, an open bowl is used. Heavy pieces like this are difficult to fire evenly and encourage under fired areas where pinholes are more likely to appear.
Why is this cone 10 oxidation iron-brown glaze pinholing?
The glaze is simply insufficiently melted. In cone 10 reduction the iron acts as a flux and it melts very very well , so there are no pinholes. But here it simply does not have enough fluidity to heal the disruptions caused as gases escaping from the body below bubble up through it.
What is an oversize particle?
Oversize particle is a fact of life in bodies made from refined materials and used by potters and hobbyists. Industrial manufacturers (e.g. tile, tableware, sanitaryware) commonly process the materials further, slurrying them and screening or ball milling; this is done to guarantee defect-free glazed surfaces.
What is the difference between Plainsman M340 and M340?
The difference is a slow-cool firing. Both mugs are Plainsman M340 and have a black engobe inside and partway down on the outside. Both were dip-glazed with the GA6-B amber transparent and fired to cone 6. The one on the right was fired using the PLC6DS drop-and-hold schedule. That eliminated any blisters, but some pinholes remained. The one on the left was fired using the C6DHSC slow-cool schedule. That differs in one way: It cools at 150F/hr from 2100F to 1400F (as opposed to a free-fall). It is amazing how much this improves the brilliance and surface quality (not fully indicated by this photo, the mug on the left is much better).
What is bisque fired to cone 06?
Second, the body was only bisque fired to cone 06 and it is a raw brown burning stoneware with lots of coarser particles that generate gases as they are heated. Third, the glaze contains zircopax, it stiffens the melt and makes it less able to heal disruptions in the surface.
Why is reduction gas firing so popular?
Reduction gas firing is known to produce much fewer glaze defects, the reason is often that the kiln, because of its mass, cools much slower. Some glaze chemistries are much more prone to pinholing. For example, high Al 2 O 3 and ZrO 3 stiffen the glaze melt making it less able to heal defects.
What is a pitted lid?
Pinholing (aka pitting) is the appearance of small holes or corroded areas on the undersides of the metal lids of your home canned foods.
Why does my lid pinhol?
Pinholing may also be caused by too little headspace, letting acidic food come in very close contact with the lid underside above it:
Why do salmon have black spots on the lid?
The black spots found on the underside of the lid from home canned salmon ….. result from the interaction between the food (fish) and the containers (metal in the cans or metal in lids of glass jars). These are black iron sulfide deposits that are caused by the high processing (canning) temperatures breaking up the sulfur compounds in the fish proteins, which then combine with iron. The deposits are more commonly found in the head-space of cans or jars, but can become mixed in with the product as well.
Is salmon safe to eat?
The black sulfide deposits are not harmful; they are just unattractive. The salmon is safe to eat. The recommendation is to eat all the canned salmon within a year of canning. Do not try to store the salmon for years because the can will continue to break down over extended storage. Eventually tiny pinholes will form in the can and cause the can to lose its vacuum seal.
Is Tattler lid made of metal?
Note: Tattler Lids are unaffected by the pinholing issue as they are not made of metal.
Do cans have enamel?
Cans are now coated with an enamel lining that prevents much of this interaction from happening. But, the enamel lining formula was changed in the past few years and there has been a significant increase in the reports of sulfide deposits in fish products, as well as other products that use these type of enamel coated cans.
What are pinhole cameras made of?
There's so many pinhole cameras out there nowadays. — Michael Ruiz, Fox News, 19 Feb. 2021 Rudimentary devices often made out of household objects like shoeboxes and aluminum foil, pinhole cameras consist of film and a light-proof box with a very small hole.
What does a pinhole in a bedsheet look like?
The water was leaking through a pinhole in the pipe. pinholes in a bedsheet will look like stars if you shine a light from behind it. Recent Examples on the Web When the eclipse begins, put your eye up to the second hole, while holding the box so that the sun is shining into the pinhole in the aluminum foil.
What is pinhooking a yearling to a juvenile?
Yearling to juvenile pinhooking involves a lot of patience, you need to know how to develop speed in a juvenile so that when it comes time for the sale, they show it then. A good showing at a 2 yo in training sale will yield higher profits. These are considered “race ready” two-year olds in training.
What is the next level of pinhooking?
The next level of pinhooking as discussed in the previous paragraph would be purchasing a yearling which would involve a much higher investment than a weanling purchase , the development in this area of pinhooking is much different and is also termed yearling to juvenile pinhooking.
How to calculate profitability of pinhooked juveniles?
A pinhooked juvenile is considered profitable if its net 2-year-old price price minus a 5% sale company commission exceeds the yearling sale price plus $20,000 for expenses such as breaking, training, and general upkeep. The rate of return is the percent difference between the net 2-year-old price and the yearling costs.
What is pinhooking?
Pinhooking what exactly is it and why do people do it? The game of horse auctions/ breeding sales is not always as straightforward as horses just being sold for profit. It often will involve a buyer/investor who spot horses based on pedigree and confirmation for future development. This is the profession of pinhooking.
Is pinhooking dangerous?
The risks of pinhooking can be volatile. Injuries, horses not developing the right way and having a less than ideal stature and last but not certainly least not performing exceptionally well at the breezing show. Several things are looked at in a breezing show such as, reach, fluid stride, confirmation, good radiographs and fast blazing breeze times.
Where did the term "pinhooking" originate?
The term “pinhooking” originated in the old Kentucky tobacco industry . Farmers would sell younger tobacco plants and speculators would purchase the younger crop to continue to cultivate themselves. After the plant matured to the next stage, the speculator would sell it for profit.
What Does Pinhole Mean?
A pinhole is a pore-like penetration that is present in paints and coatings due to the entrapment of moisture, air, solvents or other fluids. The presence of pinholes increases the corrosion rate experienced on a surface due to the moisture pockets that cause crevice corrosion, pitting and increased redox reactions.
How can pinholes be prevented?
Pinholes are a coating defect (holiday) can be prevented by the use of surface tension reducing agents to transport air bubbles to the surface of a coating.
What is a pinhole in a firewall?
In computer networking, a firewall pinhole is a port that is not protected by a firewall to allow a particular application to gain access to a service on a host in the network protected by the firewall. Leaving ports open in firewall configurations exposes the protected system to potentially malicious abuse.
Why do firewalls close pinholes?
Firewalls sometimes automatically close pinholes after a period of time (typically a few minutes) to minimize the security exposure. Applications that require a pinhole to be kept open often need to generate artificial traffic through the pinhole in order to cause the firewall to restart its timer.
Can a pinhole be created manually?
Pinholes can be created manually or programmatically. They can be temporary, created dynamically for a specific duration such as for a dynamic connection, or permanent, such as for signaling functions.
Why is the pinhole occluder used?
This can be used to distinguish visual defects caused by refractive error, which improve when the occluder is used, from other problems, which do not. The pinhole occluder can also be used in testing visual acuity in mydriatic patients.
What is an occluder in optics?
Pinhole (optics) A pinhole occluder is an opaque disk with one or more small holes through it , used by ophthalmologists, orthoptists and optometrists to test visual acuity. The occluder is a simple way to focus light, as in a pinhole camera, temporarily removing the effects of refractive errors such as myopia.
How does looking through a tiny hole work?
Squinting and looking through a tiny hole made with a finger works similarly to a pinhole occluder, by blocking light through the outer parts of the eye's lens. An improvised pinhole has a similar but better effect.
What Does Pin-Holing Mean?
Pin-holing refers to a small, sunken area that forms on a coating film after a bubble ruptures. Pinholes are typically larger and less abundant across a coating's surface than solvent pops.
What causes pin holes in epoxy?
Pin-holing are tiny holes in the finish caused by surface porosity or other imperfections in the substrate. It is an occurrence of small holes which provide a path of exposure to the substrate from improper spray atomization or segregation of the resin from the pigment in the coating. For example, in thin film epoxy coatings, excessive heat can cause similar effects by foaming the resin.
Can you inspect a surface before applying topcoat?
Coating applicators have several options for minimizing the formation of pinholes. They can inspect the surface and correct porosity or surface imperfections in the substrate before applying the topcoat. After thorough drying of the affected area, it must be sanded completely smooth, and undercoats reapplied as necessary and refinished depending on the system.
