Category Archive: Medical Grade

Filters: A Key Tool in the Fight Against Covid-19

For over 4,000 years, the evolution of the filter has been directly linked to the improvement of human health and life expectancy. The first great civilizations, like the ancient Egyptians, used sand and gravel as filter media to improve the taste and appearance of water. Today, filters have become an essential component to our entire way of life. They are found in countless industries, manufacturing facilities, processes, and in many cases, the end products themselves. More importantly, filters are enabling the tools and devices that are essential to defeating this invisible enemy and returning the world to some semblance of normalcy.


Since the onset of this pandemic, our society has gained a new appreciation for respirators, ventilators, and vaccines, as well as the vital role they play in saving lives and preventing future outbreaks. Like everything else in our modern industrial society, these life-saving tools all rely on specialized filter media and advanced filtration technology to function. It is obvious how filters are utilized in equipment like respirators and ventilators, but when it comes to vaccines the use of filter technology is not immediately apparent.

How are filters used for making vaccines?

Covid 19 Vaccine

A successful vaccine is the result of complex scientific processes that include the concentration of proteins and enzymes, blood plasma purification, virus and bacteria concentration and removal, as well as cell harvesting, clarification and washing. These procedures are all enabled by specialized filters and equipment.

Some common methods used in bioprocessing include membrane filtration, tangential flow filtration, centrifugation, and depth filtration. Implementing the proper filtration technology can have a positive effect on yield, product consistency, and overall efficiency of the entire operation.

What types of filters are used?

Hollow Fiber Filters

Hollow fiber filters possess excellent filtration performance and are commonly used in dialysis, water purification, reverse osmosis, separation of components from biological fluids, and cell culture devices to name a few.

Cartridge Tangential Flow Filter

Tangential flow filtration (TFF) systems are used extensively in the production of vaccines and other pharmaceutical drugs. They can be used to remove virus particles from solutions, clarify cell lysates, harvest and retain cells, and they can concentrate and desalt sample solutions ranging in volume from a few milliliters up to thousands of liters.

Hepa Filter Small

HEPA (High Efficiency Particulate Air) filter works by forcing air through a fine mesh that traps harmful particles such as dust mites, pollen, pet dander, smoke, and even airborne viruses. HEPA filters are used in applications where contamination control is required, such as the manufacturing of semiconductors, disk drives, medical devices, food and pharmaceutical products, as well as in homes, vehicles, and hospitals.

How is Hapco involved in the filtration and ultrafiltration industry?

Hapco has been custom formulating adhesives, sealants, and potting compounds for some of the world’s largest filter manufacturers for over 40 years. Our materials and processing equipment are a key component to manufacturing a wide variety of specialized filters. As a preferred supplier to corporations like MilliporeSigma, Pall Life Sciences, and Koch Membranes, we take pride in our ability to provide customers with the highest quality polymers and the most reliable processing equipment available.

BPA Free

As we look to a post-pandemic future, our chemists are developing new formulations and processing methods to meet the needs of filter manufacturers around the world. We are currently conducting in-house testing on Filter-bond™ R-3590: a new epoxy formulation for the filtration market that is both Bisphenol-A (BPA) and nonylphenol-free.

What other Hapco products are used to manufacture filters?

Filter Bond 2020 Cover

The Filter-bond™ series was first developed in the 1980’s for various filtration and ultrafiltration applications. It includes formulations that do not contain aromatic amines or carcinogenic or mutagenic materials, systems that can be used to pot moist membrane material in place without foaming, and systems that are easily trimmed when used for pre-potting filters. Filter-bond™ includes a line of flexible and rigid materials to meet a wide variety of filtration applications. All Filter-bond™ products are compatible with Hapco’s MiniFIL and RapidFIL dispensing machines, which are used for potting or encapsulating various filter media.

Final Thoughts

Filters are one of mankind’s greatest achievements and a major reason our life expectancy has increased dramatically over the past 200 years. They clean the air we breathe, the water we drink, the fuel that moves us forward, and the medicine that keeps us healthy. Without them, there is simply no way to manufacture the life-saving and preventative drugs that offer us a light at the end of this tunnel.


Fun Fact: Hippocrates (460-370BC) was the first major proponent of water filtration in recorded history. He advised people to first boil, then filter water through two sewn together pieces of cloth which eventually came to be known as a Hippocrates’ Sleeve.

Casting a 2-Part Mold in 1 Day

8:00AM – 10:30AM

Step 1

Use some clay to raise the part from the parting board and orient the part to maximize the flow of material and minimize the amount of air that could get trapped.

Step 2

Build up a mound of clay underneath the part, leaving room for the gate and vent. The angle from the clay to the board should be greater than 90º to make de-molding easier.

Step 2 - Top View

Make sure there is a complete seal between the edge of the part and the clay to avoid undercuts.

Step 3

Using Greast-It™ Wax P or another wax release agent, wax and buff the parting board and registration buttons. This will help seal it and act as a buffer between the board and the Grease-It™ Two.(PVA spray release)

Spraying PVA Release

Using a Spray Gun, evenly coat the part and board with Grease-It™ Two. This is a Polyvinyl Alcohol which forms a thin film that polyurethanes or epoxies won’t stick to. It is water soluble and can be easily washed off with soapy water.

Drying Release Between Coats

Using a household hair dryer, dry the release agent in-between coats to speed up the process and ensure a smooth, even coating. Generally, 2-3 coats should be applied.

Framed Parting Board & Pattern

After releasing the part, create a frame around it and mount it to the parting board. This should be at least .5” from the part on all sides but no more than 2” to minimize cost and shrinkage. Make sure to seal the edges where material may leak from using hot glue, clay, or wax.

Back Plate

We are filling this particular mold through a backplate that will be permanently attached to the rubber once it’s cured. Drill vent holes roughly 1 1/2” apart all over the top and add one larger hole that will be used as the fill port.

Secure Mold

Secure the mold frame and parting board to a flat surface or a vibrating cart. This will allow the air to rise to the top more easily.

MiniFIL Dispenser

For this straight casting application, we are using Hapco’s

MINIFIL™ dispenser. This meter mix machine is necessary to save time and money and eliminate the measuring, manual mixing, and mess associated with casting urethane rubbers and plastics. This particular mold will be cast using Hapco’s Steralloy™ 2036-5.

Noon – 5PM

Demold & Clean Mold

Using a slightly rounded filleting tool, remove the clay from the pattern. Be careful not to gouge or stab the mold because it is still very soft.

Surface Close-up

When all of the clay is removed and the part is clean, add another piece of half round wax to the top of the other half.  Use clay or wax to connect the gate and vent to the part.

Spray PVA on Mold Half

Using a spray gun, evenly coat this half of the mold with Grease-It™ Two

.  Use a hair dryer in-between coats to speed up the process and ensure a smooth, even coating. Repeat this process 2-3 more times.

Tape Frame

TIP: Apply tape to the top of the frame and then remove it after the second half is cured. This will create a tighter seal between the two halves of the finished mold.

Final Prep

Cut and drill a second backplate and screw it onto the frame. Seal around the seam line of the two halves using tape, hot glue, clay or wax.

Ready For Filling

Secure the mold box to a vibrating table using clamps or straps to make sure the mold doesn’t vibrate off of it during the filling process. Again, we are using Hapco’s MINIFIL™ dispenser. This half of the mold will also be cast using Hapco’s Steralloy™ 2036-5.

Finished Two-Part Mold

In just one day we have created a two part mold using Hapco’s Steralloy™ 2036-5. This material is considered food grade and very soft with a

durometer of 35A. It’s 5 minute gel time allowed us to get the job done fast.