A lab stirrer is a device used for mixing, blending and agitating liquids in laboratory containers. Many different types of lab stirrers exist, from magnetic stirrers to overhead stirrers, and there are different mechanisms and designs for each type.
A magnetic stirrer uses a rotating magnetic bar or plate to generate a rotating magnetic field. This rotating field causes a stir bar, which is often made from ferrite or other magnetic materials, to move inside the container, stirring the contents.
An overhead stirrer is a device used to agitate viscous material in a large container. It features an adjustable pallet drive and a shaft-mounted impeller that rotates at a adjustable speed. This motor-driven impeller pushes liquid, creating a vortex which moves the liquid downward and then back up through the container, creating a stirring effect.
Other stirrers, such as heating mantles, hot plates, and vibrating stirrers, use a variety of mechanisms to create the stirring action. Heating mantles use heated belts, hot plates use heating elements, and vibrating stirrers use a combination of an oscillating motor and a stir bar to create a counter rotary movement.
No matter the type of stirrer being used, the main purpose is to keep the liquid moving, facilitating its mix with other liquids and allowing for more homogenous mixtures. Stirrers are very useful tools for chemists, biologists, and other laboratory technicians.
What is a stir plate in chemistry?
A stir plate in chemistry is a laboratory instrument which is used to spin and agitate small amounts of liquid contained in a vessel, usually a beaker or flask. Stirring the liquid helps to evenly mix the contents, prevent settling, and keep the temperature more even.
This is especially useful for sensitive experiments, such as when working with delicate living organisms like bacteria or yeast culture. Stir plates typically contain one or two small electric motors and a removable platform that the vessel can be set on.
The motors generate rotating magnets that cause the platform to spin and the liquids in the vessel to be agitated. Stir plates are widely used in microbiology, biochemistry, and molecular biology labs.
What is the purpose of a stir bar?
A stir bar, also known as a stirring paddle or stir bar, is designed to be placed in a container where liquid or solid needs to be mixed or dissolved together. The stir bar operates by creating a swirl or vortex within the container, which helps to mix the contents.
Stir bars are commonly used in laboratories to mix solutions, or to quickly break down powders like salt, sugar, or other seasonings in liquids. Additionally, they are used to stir paint, making sure that any clumps of pigment or other particles are broken down and distributed evenly.
Stir bars are also useful for extracting flavors from herbs, spices, and other ingredients. Stir bars are used in many home and industrial settings and come in a variety of shapes, sizes, and materials to meet any stirring requirement.
How do you use a hot plate stirrer?
Using a hot plate stirrer is a relatively simple process. First, make sure the hot plate stirrer is plugged into a power outlet and set to the desired temperature. Place the desired vessel on the hot plate, ensuring it is securely and safely attached.
Add the appropriate chemical components to the vessel and place the stir bar onto the hot plate. For best results, ensure the stir bar is fully submerged in the liquid.
Once ready, turn on the hot plate and the magnetic stirrer will begin to rotate, stirring the components in the vessel. Adjust the speed and temperature as needed. When done stirring, turn the hot plate to 0, the magnetic stirrer will shut down and stop stirring.
Finally, remove the vessel and stir bar from the hot plate, safely dispose of any chemicals, and unplug the hot plate.
What are stir bars made out of?
Stir bars are usually made out of a variety of materials, including plastic, stainless steel, and PTFE (polytetrafluoroethylene). PTFE is the most commonly used material and is sometimes referred to as Teflon.
Stir bars are typically hollow or solid and can come in a variety of shapes and sizes to fit different applications. As plastic is not very durable, it is generally not used for extended stirring operations.
Stainless steel is a more robust and reliable material but can be more expensive than PTFE. There are also specialty types of stir bars available that are ideal for more intensive applications. These include fused quartz, glass, and diamond-coated.
As stir bars may come in contact with various chemicals, it is important to choose the right type for an application to ensure safety and desired performance.
How often should you stir your liquid culture?
It is recommended to stir your liquid culture medium at least once every 24-48 hours. Stirring helps to evenly distribute the nutrients in the medium, thereby ensuring a uniform nutrient concentration throughout the growth medium.
It also helps aerate the medium, providing oxygen for the bacteria to breathe. Additionally, stirring helps to reduce settling of components, which can lead to localized zones of higher or lower nutrient concentration.
Stirring should be done gently so as to not damage any fragile bacterial colonies, which could adversely impact growth. Finally, it is important to not over-stir the medium; overly vigorous stirring can reduce the effectiveness of the oxygen aeration, and can also cause turbulence that could potentially dislodge bacterial colonies.
How do you make stir bars?
One way is to purchase metal rods, such as brass or aluminum, and cut them to the desired length with a hacksaw. Once cut to the desired length, the metal rods can be bent into a stir bar shape (or other desired shape) with a hammer and a vise.
After shaping the rod, holes can be drilled into the metal to allow for a screwdriver or other tool to easily attach the stir bar to a stirrer. After drilling the holes, the metal should be cleaned with a wire brush to remove burrs or sharp edges.
Finally, a clear or colored coating can be applied to the metal to increase its corrosion resistance.
Why do you need a stir plate for yeast starter?
A stir plate is a laboratory tool used to create a more optimal environment for optimal yeast growth. In the process of making beer, yeast starters are used to propagate a large amount of active yeast to provide the most efficient fermentation.
Using a stir plate helps to create the most ideal environment for yeast starter growth as it increases the rate of oxygen incorporation into the wort, which is essential for yeast growth and fermentation.
Furthermore, a stir plate helps to mix up cold and hot spots which could form in the wort, allowing for a more even distribution of nutrients, which is needed for a healthy yeast starter. Additionally, stirring the starter can help to reduce the chance of contamination from wild yeast and bacteria.
A stir plate also helps to keep the yeast in suspension, which ensures that all of the cells can access the sugar in the wort needed for fermentation. Overall, a stir plate provides the optimal environment for yeast propagation, helping to make a healthier and better tasting beer.
How long should yeast starter sit on stir plate?
The amount of time a yeast starter should sit on a stir plate can vary depending on the strain of yeast used and the brewer’s desired level of attenuation, but generally speaking, a good rule of thumb is to let a starter sit on the stir plate for between 24 and 48 hours.
During this time, the yeast will begin to multiply rapidly, and the starter will become more and more active. This activity is important for the fermentation process and helps the yeast produce the desired flavors and aromas in the finished product.
After the desired level of activity has been reached, the starter should be harvested, cooled and pitched into the fermenter to begin the fermentation process. While 48 hours is typically enough for most strains, some brewers may opt to let their starter sit up to 72 hours depending on the desired flavor and aroma.
Should you stir your yeast?
Yes, you should stir your yeast. Stirring your yeast is an important step when making bread because it helps to evenly distribute it in the dough. When you stir yeast, it helps to incorporate air into the dough, allowing it to rise more evenly.
Additionally, stirring yeast can help to activate it and get it ready for rising. When yeast is not activated, it may not work as efficiently and can prevent your dough from rising properly. It is also important to stir yeast quickly, as too much agitation can lead to the yeast being killed, preventing your dough from rising.
To achieve the best results, always be sure to stir your yeast thoroughly with a wire whisk or wooden spoon in a circular motion.
Should I stir during fermentation?
No, generally speaking it is not recommended to stir during fermentation. It can cause oxidation of the mixture, as well as introduce yeast and bacteria that could affect the flavor of the beer. Introducing oxygen during fermentation can also lead to off-flavors, so it is best to avoid stirring.
Additionally, stirring can cause the beer to foam up, which can lead to a messy hassle. If the beer is left undisturbed during fermentation, it is possible to achieve a clearer beer as the yeast and other sediment will settle to the bottom.
Additionally, the flavors of the beer will be much more consistent and balanced without any agitation. Generally speaking, it is best to leave the beer untouched during the fermentation process.
Do you aerate before or after pitching yeast?
The answer to this question depends on what kind of beer you are brewing. For many beers, it is generally best to aerate before pitching yeast in order to ensure adequate oxygen levels for yeast growth, health, and fermentation.
This can be done by pouring the cooled wort into a bucket or carboy and gently splashing the wort around to help increase the oxygen levels. For beers such as Lagers, however, oxygen levels are kept low, and it is better to avoid aeration prior to pitching yeast.
This is best done by using an oxygen-free environment when transferring the cooled wort to a fermenter, such as using a sanitized stainless-steel auto-siphon and tubing, or by transferring the wort with CO2.
In either case, once the yeast is pitched it is important to give it a good stir in order to help the yeast distribute and absorb oxygen.
What happens if you Stir the yeast?
Stirring the yeast helps to rehydrate it and activate the live organisms that make it perform its desired leavening action. Without stirring, the hydrated yeast could form clumps or pockets, resulting in inconsistent results.
When stirring, it’s important to be gentle to avoid damaging the yeast cells. Yeast should be stirred for about a minute to ensure the yeast cells are evenly dispersed throughout the mixture. Once the yeast has been rehydrated, you can use it immediately or let it sit for a few minutes.
If you’re using active dry yeast, you should let it sit for five minutes before using it, to give it enough time to reactivate and become foamy. Once your mixture is ready, you can measure it out into different containers or recipes as needed.
How do you add dry yeast to wort?
Before adding the dry yeast to the wort, you need to make sure that the wort is cool and between 65-72°F (18-22°C). If the wort is too hot, it can kill the yeast, affecting the fermentation process. When the wort reaches the right temperature, you can add the dry yeast directly to the surface of the wort.
Gently stir the yeast in to ensure that it is completely dispersed in the liquid. Once the yeast is completely dissolved, cover the fermenter with a lid and the fermentation process can begin. After the fermentation is completed, the yeast should be removed from the fermenter using a strainer or siphoning.
What happens when yeast is added to wort?
When yeast is added to wort, the yeast feeds on the sugars in the wort and creates carbon dioxide and alcohol. This is known as the fermentation process, which is an essential part of the beer brewing process.
During fermentation, yeast also releases flavor compounds that give beer its unique flavor. Additionally, during the fermentation process, the yeast settles out and the beer is typically clarified with filtration or fining substances like isinglass or gelatin.
This helps to create a clean, smooth, drinkable final product. Once fermentation is complete, the yeast is then removed from the beer, leaving behind a delicious and alcoholic beverage that is great to enjoy with friends.
How do I know when my yeast starter is done?
You can tell when your yeast starter is done when you notice increased airlock activity, a strong yeasty aroma, and a foamy head. Additionally, the gravity of the starter should begin to drop (which may be difficult to detect when working with small starters) and you should begin to see evidence of sediment in the starter.
If the starter is over 6-7 days old, a dark layer of liquid at the bottom may form indicating the starter is finished. Finally, you could take a hydrometer reading of the starter and compare that to the OG of your wort to ensure fermentation is complete.
What can I use for a magnetic stir bar?
A magnetic stir bar (or commonly known as a flea or stir bar) is a type of small solid used in a wide range of scientific and laboratory applications. Magnetic stir bars are typically cylindrical in shape and can range from a few millimeters in length, to up to several centimeters in length.
The main purpose of a magnetic stir bar is to agitate and stir solutions inside a flask or beaker when placed in a magnetic field.
Magnetic stir bars are usually made of a ferromagnetic material such as stainless steel, and will contain a magnet at one end. The magnets are usually oriented so that the poles of one magnet can be attracted to the other magnet when placed inside a magnetic stirrer.
When placed inside a stirring device, the magnetic force between the stir bar and the stirring device will cause the stir bar to rapidly rotate, which in turn agitates the contents of the container.
Due to their small size, magnetic stir bars make it possible to quickly mix, stir or heat small amounts of liquids without the need for complicated mixing or stirring equipment. Magnetic stir bars are most commonly used in laboratories for tasks such as mixing reagents for reactions, mixing media for cultures and dissolving solid compounds in liquid solutions.
They are also commonly used in classrooms for illustrating features like Brownian motion, since the rapid movement of the stirred particles is easily visible. However, magnetic stir bars can also be used in situations outside the lab or classroom, such as stirring paint or food.
