How to chop straw?

Hi all!  Just wondering if anyone has found a good way to chop straw to use for plaster.  I’ve heard of leaf shredders breaking, people clipping with scissors by hand, and sticking a weed wacker in a 5 gallon bucket.  Anyone have a good way to get chopped straw for plaster?

Chaff cutters were made to do that.
try here for an idea Chaff cutters

For plaster? I assume it has to be cut incredibly fine.

I have seen wood chippers with a very fine screen that could possibly produce what you need.

The traditional method was to employ a horse, who would crop it fine, partially ferment it like saurkraut, open gates and cause mischief, enchant teenage girls who read romance novels, and leave apples of the magical substance you seek (after you wash it out of course).

Liza instructed Henry to use an ax. Somehow doubt that is the answer your looking for:)

Hi Kadin,

If you're chopping straw for plaster on a straw bale building, a lot of the loose straw that gathers underfoot from cutting notches in bales, resizing, and trimming is entirely suitable for base coats.  This straw tends to be long--3" to 6" or so, but can have shorter lengths.  

When we're building where the straw bale walls are stacked with the bales laid flat (strings not exposed), we shave the walls with both chainsaws and angle grinders equipped with a Lancelot blade.  This finer straw piles up at our feet, and tends to be much shorter--lengths of 1/2" to 2"--which we bag for use in base coat plasters, too.   For truly fine straw for a finish plaster--lengths under 1", and preferably shorter, we have screened the straw, which can be very time consuming.

If we find that we don't have enough shortish fiber straw (1" - 3") straw for base coats we'll use a chainsaw to take 1" - 3" slices from an intact bale.  it takes just a few bales to make a large pile of shorter fiber straw this way!

On jobs where we're applying a three-coat clay plaster to a wall other than straw bale we'll bring a few bales over to a neighbor who operates a grain thresher, which makes very quick work of converting bales into short straw fibers (1" - 3").  You can also use a leaf shredder or chipper too, though it may take a while.   We find that if you control the feed rate--don't dump it all in at once--and the outlet screen is in place,  the machine won't choke and you should get good material for base coats.  

I haven't had as much success with running a lawnmower over loose straw, or using a string trimmer in a large garbage barrel, at least 20 gallons, and preferably larger.  I don't think my string trimmer heads would actually fit into a 5 gallon bucket!   I know people use those methods, but I haven't done that since the early 2000s.

Jim Reiland
Many Hands Builders
S. Oregon

Wow thank you!!  So much great info!  I’ll plan on using as much of what is on the ground and besides that probably shave off bits with a saw of some sort.  I haven’t had use for a chainsaw yet but maybe I’ll just give it a go with the reciprocating saw.

Thanks for the thoughts!  Much appreciated!

In a pinch, I have used a hand-held circular saw (battery or corded) to cut notches in straw bale wall for ledgers.  The cut is only as deep as the blade--less than 3"--but you need to make a lot of passes to clear the "waste," which makes for smaller bits of straw.  Be sure to clean the tool afterwards--electric tools made for cutting wood benefit from a blast of compressed air to clear the dust from the vents.

Jim Reiland
Many Hands Builders
S. Oregon

People have used an electric weed whacker in a trash can or barrel.

I saw a post here yesterday, Uncle Mud testing a leaf shredder that seemed to be doing a good job. Will see if I can find it.

Here: https://permies.com/t/207064/Uncle-Mud-Review-Chopping-Straw

Although others have voted down the notion above, I found much success on my straw bale build using the weed-trimmer-in-the-metal-trash-can approach.  It produced all of the chopped straw for my plaster reliably enough, and more-or-less speedily enough.  Don't put too much in at once.  And unless you want to end up wearing a lot of straw dust, drape a piece of clear plastic over top of the trash can.  It need not be taped down - though you can do that too, if you like - but it should still cover most of the opening, with your weed trimmer stuck in from one side underneath the plastic.  That way you can still see what you're doing and most of the straw and dust is contained.

If you don't mind wearing all of the dust, that's fine too, but wear a good dust mask!

With this approach, I found that you can make as much chopped straw as you like, to whatever length you like.  The finer you want it, the longer you keep it in the chop can.  For my base plaster coats, I aimed for an average length of 1.5" or shorter.  I didn't use any straw in my finish coat.

The best thing about producing your own chopped straw this way is that it is clean!  At first, I was saving the trimmings from carving bales - as some above have advocated - but I quickly gave that up as unwanted debris would invariably end up in my plaster!

I was pleasantly surprised to find chopped straw in bagged for sale as animal bedding at my local farm store.  Depending on your budget, it might be worth the small expense for the labor savings involved.

This stuff--although purchased and maybe hard to source--has great texture and dryness. Great for animal bedding, avoid any types with pellets for plaster: https://www.facebook.com/576395582542310/posts/flax-bed-animal-bedding-12x-more-absorption-than-straw4x-more-absorption-than-wo/1008033489378515/

When we were plastering our straw-bale walls, we placed 3 intact bales on the ground in a the shape of the letter "U", then took an ordinary lawnmower with a mulching  blade, threw several flakes of straw in the middle of the "U", and let the mower mulch them up. Then we swept up and bagged the choppings, and did the whole thing again.  One person running the mower for half an hour could make quite a volume of chopped straw...

You can also use toilet paper! I'll try it next week, it looks very easy! Check this: https://www.youtube.com/watch?v=WQlolVGRWic

Good luck! :)

Kārlis Taurenis wrote:You can also use toilet paper! I'll try it next week, it looks very easy! Check this: https://www.youtube.com/watch?v=WQlolVGRWic

That is extraordinary!  I wish he had shown more of the mixing process.  The results are undeniable - just look at how smoothly that plaster trowels on!  I omitted any fiber reinforcement on my exterior finish coat.  For my interior I will surely try this method.

best thing I found was a kemp shredder, heavy duty and it makes straw so fine that it's perfect for filling and plaster.

Kyle Moss wrote:best thing I found was a kemp shredder, heavy duty and it makes straw so fine that it's perfect for filling and plaster.

Please explain: what is a kemp shredder?