Cavitating Blender

December 1, 2015 5:18 AM

How do I keep my blender from cavitating when making thicker things?

I have an inherited Oster Classic VIII blender which I use for soups and such. When I use it to make thicker things, it inevitably cavitates and spins merrily while the food remains above an air pocket unblended.

I've been recently having frozen bananas and berries blended together and that only works if I add some milk and vanilla to loosen it up and guide some of the frozen stuff into the blades with a wooden spoon until it's ground up enough to run itself through.

I'd prefer to use no milk at all, but I'd also prefer to not pick out wood chips from my breakfast. Is there a better technique? Better blender? Food processor? Dropping the banana pieces in gradually?

posted by plinth to Food & Drink (15 answers total)

More questions than answers:

Have you tried filling the blender with less stuff? What about blending one or the other first to see if that will liquefy enough to work the second item down? Or thawing out the ingredients a bit first? It sounds like you're asking the blender to be a food processor, too. What kind of blender is it, because maybe you just need something more powerful.
posted by Room 641-A at 5:27 AM on December 1, 2015

Oh, I missed the obvious link to your blender. You need a smoothie maker.
posted by Room 641-A at 5:28 AM on December 1, 2015

Best answer: A high end blender like a Blendtec or Vitamix may not solve the problem. Vitamix comes with a tamper for just this reason. Blendtec swears you don't need one, though I've heard Blendtec might be kind of lying about that.

Ironically, I've found that the lowest of low end blenders -- the MagicBullet -- has this problem the least, just because it uses serving sized containers that don't give anything room to cavitate. There are other smoothie blenders on the market with single serving sized containers, as well.

Putting chunks in a couple at a time ends up not helping that much, because the first chunks get blended and then the last chunks just sit on top of whatever you've already blended getting not blended.

It can help to use your pulse button if your blender has one and tamp the food down in between pulses. Pulsing rather than straight blending reduces cavitation, and tamping between pulses reduces the likelihood of terminal spoon damage.
posted by jacquilynne at 5:35 AM on December 1, 2015

One other thing to try, take the blender off and tap it down on the counter, pulse at slow settings, tamp, repeat. Patience and go slow.
posted by sammyo at 6:26 AM on December 1, 2015

I actually pick up the blender and shake it (while it's on) when this happens. Whether that's a good idea is debatable, but it works for me.
posted by pipeski at 6:48 AM on December 1, 2015 [2 favorites]

With our Blendtec brand blender product, I often have to bop it on the top while it's running to get things to drop and that's not even foolproof. The only reliable solution seems to be more liquid.
posted by mattamatic at 7:48 AM on December 1, 2015

Response by poster: Picking up the blender would be a good idea if this particular blender was anything but a product of the "Our Friend the Atom" school of design. The base is a solid hunk of chrome plated metal and the carafe is glass.
posted by plinth at 7:51 AM on December 1, 2015

Oh hey, I have a slightly different model but nevertheless an ancient Oster. Sad to say it, but this is just par for the course. The upshot is that these things are built to survive a nuclear winter, but nevertheless in the almost-decade that I've been using ours (my partner's had it since the 80s!) I've never figured out a more elegant solution than stopping frequently to scrape down the sides.

If your model has the pulse button, instead of only allowing on/off, I find a lot of success with gingerly pulsing repeatedly at the beginning to break thick/huge things up without spinning them out against the blender walls. But, yes, still have to scrape the sides constantly.
posted by late afternoon dreaming hotel at 8:23 AM on December 1, 2015

I partially thaw my berries in the microwave, just enough to make them not rock solid.
posted by antiquated at 8:42 AM on December 1, 2015

Best answer: This is why my Oster blender is now supporting the corner of a shelf with a broken bracket in my cabinets, and I use a KitchenAid. It was insanely frustrating because the blender was not broken, per se, but that square canister is a broken design.

I did a lot of stopping and scraping, adding more liquid.
posted by JawnBigboote at 9:17 AM on December 1, 2015

I used to have one of those blenders and I always used the pulse button for a few seconds at a time, but I don't remember having to scrape it down. I didn't use frozen fruit but I wonder if your chunks are too big? I would always use fresh fruit and ice cubes, and found that large ice cubes just never worked but the tiny ones from novelty trays (like this) worked just fine. I always got my novelty trays around the holidays at Dollar Tree.
posted by jabes at 9:18 AM on December 1, 2015

If your goal is to make personal serving size smoothies, I recommend this blender which you can get from amazon for around $15. It's probably not great for anything heavy duty, but I've had mine for a couple years now, and it's still completely functional. (I only ever use it to make smoothies.) You still need to use some liquid in the smoothie although I only use a pretty small amount of liquid, and the blender is small enough that if anything gets stuck, you can easily take the cup part off of the base and shake it up a few times if you run into cavitation problem.
posted by litera scripta manet at 9:41 AM on December 1, 2015

Best answer: Even using the baton in our Vitamix doesn't solve this entirely; I typically keep a small cup of juice or water to slowly add when voids occur.
posted by a halcyon day at 11:40 AM on December 1, 2015

Net positive suction head. If you're not filling the blender all the way, try that. The extra weight might make the mixture keep falling back down into the blades.
posted by ctmf at 8:45 PM on December 1, 2015

Best answer: I will add that through experimentation, I am able to get the blender to get to the point of blending without cavitation by using the following mix stacked in order in the blender:
3/4 C frozen berries
1 peeled tangerine
1.5 bananas cut in slices
1 t vanilla
1.5 t cinnamon

The resulting texture is like softserve ice cream, which is what I want and requires no additional liquids beyond the vanilla, which is minimal.
posted by plinth at 11:40 AM on December 22, 2015