Why is My Rosin Black? Expert Tips on Low Temp Rosin Pressing

“Why is my rosin so dark? Am I using the right temperature? How do I press clear rosin?”

As a master squisher who’s processed hundreds of pounds of flower into award-winning, golden rosin, Paul Lopez knows the answers to these questions. And, fortunately for you, he’s willing to share his knowledge with the world!

So, we asked him to spill all the secrets he’s learned at the Hard Knocks University of Experimentation. And while Paul can’t stand over your shoulder as you’re solving your dark rosin mystery, his step-by-step tips can help improve your rosin clarity— and the market value of your end product.

Rosin Clarity Step #1: Check the Quality of Your Plant Material

The old maxim applies: garbage in, garbage out. It’s impossible to press fire-quality rosin with lousy marijuana. The cannabinoid content of trichromes drops with time, light and oxidization, and air-volatile terpenes are even more affected by age. So, the time to press rosin for the best clarity—or best overall quality—is soon after the cure is complete.

“The fresher and the higher-quality product you have, the better it’s going to do,” says Paul. “It all depends on the grower and how fresh it is. I like to press four or five days after it’s been picked off the plant.”

For even better results, try using bubble hash made with fresh frozen material. Because the buds are flash frozen, all the trichromes and terpenes remain intact. “When you’re doing fresh frozen (bubble hash), you tend to get your best clarity out of it,” says Paul.

If you’re a commercial grower or working closely with a commercial grower, you’ll have some control over the age of the material you press. If you’re a small scale do-it-yourselfer buying flower by the ounce, you may not be so lucky. Try to find fresh material and get to know whoever’s sourcing your bud.

Rosin Clarity Step #2: Turn Down the Temperature

“When people get black rosin coming off their plates it’s because their product is very old or their temperature is too high, and they’re burning it off. Or they leave it on the plate for way too long,” says Paul.

There are no hard-and-fast rules for the best temperature for rosin clarity, and professional rosin producers all seem to be a little tired of the eternal question: ‘what temp, bro?’ But there are some guidelines for what temperatures to try first. Basically, start a little low for the best clarity.

“I start at my normal temperature—like 190°F. If I notice it took over a few minutes for the bag to start leaking out rosin and the return was really small, I know I need to jack my heat up. I’m going to check it and compare them, side-by-side. I’ll look at the colors and even weigh them to know the returns. So if that product didn’t like it at low heat, I’m going to put my temperature 10-15 degrees higher and run another ounce.”

Rosin Clarity Step #3: Experiment

Rosin pressing is an art. For the best rosin clarity, it’s important to adjust to how the plant material is behaving— even if it’s the same strain. “Even if you grew Silver OG and I grew Silver OG, and you brought me yours, and we did mine side-by-side, they’d both turn out different,” says Paul.

“Adjusting temperature is the trickiest, and it’s important just to get hands-on. Every strain is different. They’re never pressed at the same temperature. That’s the hardest part: having enough material to allow yourself to practice and learn it for yourself.”

Paul has tinkered with pressure too. Many moons ago, Paul learned rosin pressing using hair straighteners and YouTube videos. Then, he bought a t-shirt press. A 1-ton press followed and, eventually, 5-ton and 15-ton units too.

“Then I started using Triminator’s 25-ton TRP Stack rosin press. I like the higher pressure, and you can always control it to get lower pressures if you want,” says Paul.

Some rosin producers find that screen size affects product clarity, with smaller micron screens producing lighter rosin. Because the larger particles are darker than the cannabinoid-rich trichromes, a smaller screen may improve your rosin clarity. The tradeoff for a tighter screen, however, is a slightly lower yield.

Rosin Clarity Step #4: Change How You Press

To get the best rosin color, Paul romances the oil out of his herb with a fine touch rather than one big, brutal smash. Achieving a uniform temperature through the top, middle, and bottom of the bag is key for a smooth, even flow. That’s hard to pull off when you press too quickly.

“People crank down their plates really hard and fast, and you start burning your rosin,” says Paul. “You should go slower, let it pre-heat for a moment and let the bag get ‘wet.’ ‘Wet’ is what we call it. Then you start applying more pressure slowly as it goes.”

This gradual buildup to the final squeeze yields lighter colored rosin. Relative to a quicker, higher-temp smash, the oils from the top and bottom are less likely to turn dark during the time it takes for the middle-most material to melt and flow.

Some new rosin pressers may be concerned that the oil is sitting on the plate too long and scorching. Sure heat degrades terpenes, but the benefits of a slower squish outweigh the drawbacks. You’ll get more yield and better results by letting the material heat up a little before the grand finale, full-pressure squeeze. Plus, your product will never get hotter than the temperature on the rosin press temperature you’re using.

Even and consistent heat influences both rosin quality and yield quantity. That’s why we design the platens of Triminator’s rosin with full-length heating elements. Our design creates maximum heat uniformity—and the best-colored rosin possible.

Rosin Clarity Step #5: Did We Say Check the Quality of Your Plant Material?

“Really, I’m not joking. It’s the answer to almost everything,” says Paul. “The whole key to making rosin is having high-quality, fresh, clean material.” Pez Bros achieves a 70-90% yield (by weight) when pressing bubble hash, a 50-70% yield using kief, and yields ranging from 10 to 15% when pressing flower.

You might think that pressing kief or hash would give you better rosin clarity, but Paul says that isn’t necessarily the case. Yield increases with more potent input material, but the color of the rosin may stay the same.

“I’ve done flower rosins that come out looking white or light gold. It all depends on the grower and how fresh it is,” says Paul. “I can sit here all day and tell you about it, but you have to experiment lots and do it yourself. If you don’t have access to a bunch of product, that’s a problem. For people doing this as a hobby, they gotta spend a bunch of money to get good at pressing.” Check out Paul pressing some rosin on the TRP Stack.

So, unfortunately, the best advice to help you figure out why your rosin is so dark doesn’t lend any easy answers. Beyond the book learning of temperature tactics and pressing power lies the reality that you need a large quantity of killer bud that you’re willing to make mistakes with. That’s not something available to just everyone. But for those of you in a legal state with access to a good product supply, patience and a low temp rosin press should get you the golden dabs you’re after.