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Cleaning Skulls

If you’re into nature, you may also be into skulls. And if you’re into skulls, you’ve probably struggled with skull processing. To do it right you need a terrarium and some dermestid beetles, but that costs time and money. (One website is selling a colony that’ll clean your skulls in 3 – 4 weeks for $230, plus shipping and handling.) Depending on your spouse’s level of squeamishness, bringing flesh eating beetles into your basement may also cost you your marriage.

I’ve always processed skulls on the cheap, and while I’m no expert, I can offer a few probably-helpful tips to those new to the craft. If nothing else, I may save you a mistake or two.

When I was a kid I used to skin the skulls and then boil them, but I was never really happy with this method. I’d boil for hours before the flesh would loosen, and even then, I’d have grizzled bits that stuck like glue. It smelled; it seemed to shrink the skulls; it ruined pots. (If you’re thinking: oh, his poor mother, you should know that my elementary-school-teacher mom was the one who got me into this macabre craft in the first place.)

What I do now is simply put the skull, hair and all, into an oversized Havahart trap that’s wired securely to a post so no animal can drag it away. There’s a mesh tray with a layer of window screen under the skulls to hold the bones. And then I just let nature do the hard work for me. I throw some composted horse manure on top of the skulls, which seems to keep odor down. I also suspect it encourages microbes and beetles while discouraging maggots, which may not matter at all in the grand scheme of things – this is just how I do it. In a month or two, I come back and the skulls are largely clean. I’m always surprised by how little stink there is.

This method works best with big skulls. The smaller things get, the finer the bones and teeth, the more problems you’re going to have. Mice can be a particular problem, as they have a habit of walking off with skull parts if you leave enough space for them to do so. My general rule is that big skulls – deer, bear, beaver – can go in as is. With mid-sized skulls (fox, raccoon, etc.), I skin them and put a zip tie around the jaw to hold them together. This pays great dividends as it often keeps all the teeth intact in the jaw bone. With skulls smaller than that, I take pains to wrap the skull so it falls apart in a more controlled, contained way. As I said, small skulls are tough.

After nature’s taken the hair and meat off the skulls, it’s just a matter of cleaning them up. I use soapy warm water and a toothbrush to get them clean. They then go in a hydrogen peroxide bath. I’ve used bleach before and it does a fine job, but I’ve been told by reputable-seeming people that bleach degrades the bone and that peroxide is a much better way to go. In the pictures below you’ll see I’m using an old drawer and had to flip the skulls half way through. It would have been better to use a shallow tub where the skulls could be submerged completely, I just didn’t have one at hand.

I like a yellowy, natural-looking finish – bright white skulls seem fake-looking to me, like they’re made out of plastic – so I’m fine using the 3% peroxide you buy in the drug store for less than $1 a quart. You’ll need to leave the skulls in to soak for a week or so. You can buy more concentrated peroxide – 12 percent and 35 percent are two stronger options that are commonly available – which will give you a whiter and more uniform finish and will decrease your soak time. But I don’t know if you can overdo it with these concentrations, so be careful. And, of course, the more concentrated the more caustic, so be careful there, too.

Hopefully this is helpful to somebody. If I left anything out, or if someone has another tip to share, by all means chime in.

Skulls Gallery

Skulls after the natural cleaning.
Skulls after the natural cleaning. | Photo: Dave Mance III
The washing begins.
The washing begins. | Photo: Dave Mance III
Many skulls will come apart at this chin joint. It's no big deal; just superglue the two pieces back together.
Many skulls will come apart at this chin joint. It's no big deal; just superglue the two pieces back together. | Photo: Dave Mance III
After a one day peroxide soak.
After a one day peroxide soak. | Photo: Dave Mance III
A finished, natural look.
A finished, natural look. | Photo: Dave Mance III

Discussion *

Aug 26, 2014

Always have let nature do its thing (usually involved putting them up high away from critters) and then used bleach. But I like the have-a-heart idea followed by H2 Peroxide.

I am a major skull collector, along with many other woods artifacts. My wife calls my collection my own personal musuem.

Stu
Aug 10, 2014

Dave, I read your piece on skulls with more than average interest.  I wrote an article for Northern Woodlands in the summer 2006 issue titled, “Skull Session”, about this bony subject.  I used to teach a high school biology class in which preparing animal skulls was a lab activity, and the kids absolutely loved it!  Back then, we primarily used the “pick and grin then boil” technique and had great success.  I must admit, though, that most of the odoriferous boiling was done at home in my garage over a Coleman stove.

Leighton
Aug 09, 2014

I have used dermistid beetles for shrews and small birds.  They do a very fine job but the odor is something to get used to or not.  My next colony might just have an air vent system that uses nice active dirt as the filter… Set up a little computer fan that turns on a couple of minutes an hour.

Tom Prunier
Aug 08, 2014

I have tied a lot of different methods including the ones you mention, and by far the best I found was what I’ve heard called maceration. It involves a bucket of water with floating bits of yuck sitting under the sink for several months, so it’s not for the faint of heart.  But it works well for the smaller, more delicate skulls.  It is a middle step between manual de-fleshing and the finishing process with the hydrogen peroxide (which also works well). But soaking the skulls ensure that no animal walks off with littler bits, and that the bone doesn’t weaken (like it can with boiling and bleach). The flesh eases off the bone and is largely eaten by bacteria, even in the brain case.  And it gets very, very clean…eventually.  It takes patience and warmish water.

Laura Buss
Aug 08, 2014

I bury my skulls or a year or two and that takes care of all but bones

Ron Hummel
Aug 08, 2014

Way back in college I earned extra credit in a wildlife course by providing skulls for the college teaching collection. Our method for cleaning was using a mixture of bleach and water and boiling for hours and hours. If memory serves it took most of weekend day to get them cleaned up. Stunk up the entire biology hall but the finished product was nice. Still have a couple that I cleaned for myself.

Dale
Aug 08, 2014

Dave,

It seems there is so much to say, yet I’m speechless. Fascinating!

Ed

Ed Wright

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