I have a battery powered pressure washer than can suck water up from a bucket. It fortunately isn't under huge pressure like a mains powered one which got me thinking - would it fire out gunge?

I don't really want to wreck my pressure washer but if it works im up for using it.

Any advice?

I can't imagine the pump in it would be overly happy, you'd probably burn it out pretty quickly.

You would really need a slurry pump.

AL will be able to tell you more, he is probably an expert when it comes to pumping slime.

It may burn out the engine but Even theoretically if it worked Pressure washers aren't the best thing for use on human skin unless you have a very very very weak setting on it, that you tested with warer (not recommending it of course) it can cut the skin badly. There are gunge shooters though that people have made

It won't be powerful enough to propel a liquid with that viscosity and will just block.
What you need for starters is a modest air compressor

I didn't know it was possible to get battery operated ones. If you could get it working, I wouldn't recommend gunging yourself or any other person with it. Maybe inanimate objects if you felt it could be done safely. By definition, any pressure washer on any setting would be reasonably fierce, so could be catastrophic for skin and hair.

I would not ever try that. Pressure washers can cause extreme injuries, they can drive fluids through skin all the way down to people's bones where they require surgery to be opened up and cleaned out. I don't know how high the pressure is on yours, but you should not ever use anything sold as a pressure-washer on humans, it isn't worth the risk.

If you want to spray someone, you should use something like a Super Soaker water gun. Something you're sure has safe levels of pressure.

Erin, please no. Google "hydraulic injection injury", it is horrific and can be fatal.

Trying to remember who made a gunge shooter recently.

Only if you're a psychopath that wants to remove your skin :-p

High pressure jets are no joke. At point blank range they'll be VERY painful at best, and cause lacerations and hydraulic injection injuries at worst. Generally its a really bad idea to directly hose yourself with them.
If in doubt test it on a chicken leg first.

What might be an option is strapping the lance to something solid and standing down-range. Aim up so the water (test) rains down on you.

What effect are you trying to achieve? The insane pressure from a power washer generally produces a fine misting of water once you're down into a safe range.
If you're looking to produce a jet of gunge, take the nozzle off the end of the lance first. This should prevent the jet from breaking up and significantly reduce the pressure.

The pumps designed for water- so any gunge you use will need to be free flowing and your machine might survive. Oil/oil based might damage/dissolve the rubber seals on the pump too.

If you want a jet of high pressure gunge- hang a bucket upstairs and grab some 1" or 2" blue water pipe from a hardware store, and a ball valve to fit. Probably cheaper than wreaking your washer.

Rest assured - I have been put off using my pressure washer

But I wanted you to do my aluminum siding.