How To Use a Pre-Press Mold
Cannabis enthusiast and student of the art of solventless extraction
Pre-press molds allow extractors to quickly and conveniently compress cannabis material in preparation for rosin extraction. Compacting starting material eliminates gaps and inconsistencies throughout the flower, sift, or bubble hash within a rosin filter bag, allowing for an even flow of rosin as pressure is applied during extraction. If the cannabis material contains pockets of empty space, these mini chasms will collect and hold the freshly-squeezed rosin and prevent it from flowing through the filter bag and onto the parchment paper for collection.
Simply packing cannabis by hand into rosin filter bags isn’t enough to fully remove the rosin-stealing nooks and crannies within the material. A rosin pre-press mold is the perfect solution to this problem.
Pre-presses are composed of three parts including an upper plate, lower plate, and a free floating sidewall. The best pre-presses are made with 100% aluminum, making them highly durable and easy to clean and maintain. Pre-press molds are generally rectangular, resembling a shoebox shape but on a much smaller scale. The molds are designed with different dimensions to fit different size rosin filter bags, ranging anywhere from 2x4 inches to 4x7 inches with a 1.5-inch height.
Cylindrical-shaped pre-press molds are also available for pressing bottle tech style, in which rosin bags are positioned vertically in between heated press plates rather than horizontally in the traditional way. These cylindrical pre-presses, also known as pollen presses, allow for cannabis material to be pressed into puck-like shapes, which we recommend for pressing flower rosin. Pollen presses are tube-shaped with a top on either end, and function the same way as rectangular pre-press molds. You can learn more about this approach in our article How To Press Bottle Tech.
Regardless of which style you’re using to press rosin, whether it’s bottle tech for flower, or pillow tech (traditional horizontal orientation) for pressing dry sift and bubble hash, pre-press molds make it easy to prepare starting material for consistent results at the press.
Read more about the benefits of pre-pressing cannabis in 3 Reasons Why You Need a Pre-Press Mold.
Pre-Pressing within a Filter Bag or without a Filter Bag?
There are two approaches to loading material into a pre-press mold.
One way is to load the cannabis material into a rosin filter bag before placing it into the mold for compression. With this approach, the cannabis is placed in the filter bag, then the loaded filter bag is placed into the pre-press mold. When pre-pressing dry sift or hash, loading the material into a filter bag before placing it into the mold is ideal. Be sure to fill in the corners of the bag and pack the material tightly. Read more in our article about How To Pack Rosin Bags.
The other way is to place the cannabis directly into the pre-press mold, compress the material, then load into a rosin filter bag. Cannabis flowers will generally maintain their form once they’re pre-pressed in the mold, so they can be handled relatively easily for loading into the bag. Pre-pressing flowers without a filter bag produces better results than pre-pressing sift or hash without a filter bag. We only recommend pre-pressing sift and hash after it’s already been loaded into a filter bag. But with flower, some extractors prefer to pre-press the material, then put it inside a filter bag afterwards for extraction.
Loading either dry sift, bubble hash, or flower into a filter bag prior to pre-pressing has its advantages, one of which is to minimize any excess space between the material and the inside edges of the filter bag. Pre-pressing cannabis inside a filter bag allows the material to spread out evenly and fill the entire space within the bag. Pre-pressing material loaded into a filter bag presses the material flush against the entire surface area.
When material is pre-pressed outside of a rosin bag, then placed into a bag after it’s already come out of the mold, there can be gaps between the edges of the filter and the edges of the material. During extraction, these gaps lead to folds of nylon filter material that can trap rosin.
Pairing Your Rosin Filter Bags with the Right Size Pre Press Mold
Your pre-press mold should match the general shape and size of the rosin filter bags you’re using. If the mold doesn’t match the exact size of the filter bag, keep in mind that it’s better to use a pre-press mold that’s larger than the filter bag, than the other way around. You don’t want to use a pre-press mold that has smaller dimensions than your rosin bag, but it’s okay to put a rosin bag into a larger pre-press mold.
For example, 2x4 inch pre-press molds are the ideal choice for 2x4 inch rosin filter bags. 2x4 inch pre-press molds also work well for smaller bags like 1.25x4, 1.5x4, and 1.75x4 inch filter bags.
That said, rosin filter bags are usually not filled all the way to the top with cannabis, so after loading with the desired amount of cannabis, the excess nylon material at the top of the bag is cut away. So the dimensions of the actual material, not necessarily the full filter bag, is what guides your decision.
In this case, filling 2.5x4.5 inch rosin filter bags only half way with cannabis means that the dimensions of the material is 2.5x2.5 inches inside the rosin bag. Therefore, the 2.5x2.5 inch pre-press molds match perfectly.
Likewise, bubble hash is often pressed in longer filter bags like 2x9 inches, but not filled all the way to the very top. So 2x9 inch pre-press molds are the best choice.
Applying Pressure
Now that you've loaded the pre-press mold, it's time to apply some pressure. Place the mold on a table or countertop and put your hands, palms down, on either end of the mold. Lean over the mold with arms extended and press down with the full weight of your upper body for 30 seconds to a minute. You want to apply enough pressure to fully compact the material.
You can also place the loaded pre press mold into a clamp or vice grips, which is easier than pushing into it with your body weight.
Tips and Tricks
It’s important to maintain cleanliness on the inside of pre-press molds to ensure contaminants don’t make their way into your rosin. Any dust, debris, or plant material that’s inside the pre-press mold is likely to get stuck on the outside of the filter bag, and then get stuck inside your rosin as it flows out during extraction.
Clean pre-press molds after each use, especially when loading flower directly into the mold without a filter bag. Use ISO alcohol to remove any stubborn cannabis oil that may get smeared and stuck onto the aluminum.
Another trick is to use pieces of parchment paper to cover the top and bottom of the material, in between the upper plate and the lower plate and the material itself. This will help keep the inside of the pre-press a lot cleaner.
Conclusion
Pre-pressing cannabis flowers, dry sift, and kief is a key step in the process of preparing material for extraction. Pre-pressing minimizes empty space between the material and the edges of the filter bag, eliminates large gaps and inconsistencies throughout the material, and primes the trichomes for the full pressure of extraction.
Aluminum molds made specifically to match the dimensions of rosin filter bags provide the most effective means to pre-press cannabis. They are a great investment and well worth the cost to help ensure you'll get the most from your material with every extraction.
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FREQUENTLY ASKED QUESTIONS
What is a pre-press mold?
A pre-press mold is an apparatus designed for lightly pressing cannabis material in preparation for full heat and pressure during rosin extraction.
What is a pre-press mold made of?
The best pre-press molds like these from The Press Club are made with 100% aluminum.
What are the benefits of using a pre-press mold?
The main benefit is that pre-pressing material helps evenly distribute material inside the rosin filter bag, press the material flush against the sides of the bag, and minimize any gaps within the mass of cannabis material.
Do you have to use a pre-press mold?
No, but pre-pressing cannabis material helps facilitate an even flow of rosin during extraction for the maximum yield on your parchment paper.
How do you clean a pre-press mold?
Using ISO alcohol with a clean towel or cotton swab is a great way to clean pre-press molds.
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