Quick, Clean, and Done Right
If you’ve ever wondered whether a mortar (pointing) gun is worth the fuss for repointing chimneys, this video walks you through everything, from buying the right gun to mixing the perfect mortar and cleaning up afterward.
I’ll show the pros and cons, the common mistakes to avoid, and the little tips that make the job way easier. Want to skip the reading and see the job done?
Watch the full video How To Use a Mortar Gun to follow the whole job from unboxing to the final strike-off.
Why use a mortar gun?
Mortar guns let you pump mortar quickly and push it hard to the back of a joint, which means:
- Faster coverage for bigger jobs.
- Better-packed joints (less voids behind the mortar).
- Huge time savings once you’ve got the technique down.
That said, they’re fiddlier than a tuckpointing trowel if you don’t prep properly and yes, they can be messier.
In the video I explain why I still prefer a gun for chimney repointing and show how to manage the downsides. (If you want to see how the mortar packs into the joint, jump straight to the live demo: How To Use a Mortar Gun
Choosing the right mortar gun — don’t get mugged by cheap kit
When I went looking for a replacement I compared the budget options and the pro kit I’m used to.
There are cheap consumer guns out there, and then there’s the kind of “faithful” pointing gun I prefer they cost more but last longer under heavy use.
What I look for when buying:
- Solid build and spare parts availability.
- Simple nozzle options so you can control bead size.
- A gun that’s robust enough to handle frequent use (if you’re a tradesperson, buy the proper tool).
Unboxing the new 9-piece kit, I found the usual extras, spare rubbers, nozzles, a small mixing tool (handy for paint, useless for large mortar mixing). The takeaway: don’t overpay for gimmicks, but don’t expect £20 bargain guns to survive a heavy work schedule.
The single most important factor: the mortar mix
If the gun is the engine, the mix is your fuel. Get this wrong and you’ll spend more time fighting the gun than you will filling joints.
My tips:
- Use a clean, non-gritty sand, I use a yellow sand that contains no stones or grit. If your sand is stony it will block and wear the gun.
- Make the mix wetter and creamier than a normal pointing mortar so it slides through the tube easily.
- Add a plasticizer to improve flow. It makes all the difference pushing mortar through the nozzle.
- For chimney work I use a 4:1 sand:cement ratio for the repointing mix (but note: this video is focused on gun technique rather than the full mixing theory).
In the clip you’ll see me scrape debris around the joints with a trowel before loading the tube — that step prevents lumps getting pushed into the gun.
Loading, pumping and striking off — step by step
Here’s the simplified workflow I follow (and demonstrate in the video):
- Load the mortar tube (I use a gauging trowel to avoid air pockets).
- Insert the tube into the gun and squeeze a test bead to make sure everything flows.
- Apply steady pressure and push the mortar fully to the back of the joint — that’s key for durability.
- After filling a section, release the gun pressure to stop excess mortar squeezing out.
- When the mortar has firmed enough, strike off the joint to finish — a little slower than conventional pointing, but the speed you gain filling compensates for cleanup time.
If you prefer to watch the entire step-by-step in action rather than read about it, watch the full video here How To Use a Mortar Gun you’ll see the rhythm of how I work and the small corrections I make on the fly.
Cleaning and maintenance — don’t wreck your new tool
Clean the gun thoroughly after each use. Ideally blast it under an outside tap and scrub with a brush; if you don’t have a tap, a bucket and a good brush will do.
A quick warning from experience: don’t spray WD-40 into the mechanism. It seems sensible (stop rust!), but it can over-lubricate parts so the gun won’t push mortar properly — I actually found it jammed and damaged the gun once after using WD-40. Best practice: rinse, brush, dry, and store somewhere dry.
Pros and cons — is a mortar gun right for your job?
Pros:
- Fast — great for large sections and jobs where time equals money.
- Fills the back of the joint properly for a solid finish.
- Saves effort in the long run once you’ve dialled in your mix and technique.
Cons:
- Messier than hand-pointing — you’ll spend more time cleaning up.
- Can be frustrating if you’re using poor sand or the mix is wrong.
- Striking off can take longer because the mortar sets differently when pumped.
For me, the speed and the quality of a properly packed joint outweigh the downsides but the gun is only as good as your prep and mix.
Final recap and quick checklist
Before you grab your mortar gun, make sure you’ve ticked these boxes:
- Clean, non-gritty sand (no stones).
- Mortar a bit wetter than for hand-pointing.
- Use plasticizer for easier pumping.
- Test the gun flow before starting a run.
- Clean and dry the gun thoroughly after use (no WD-40!).
If you’ve got questions or want to see more close-ups, drop a comment under the video I answer as many as I can and sometimes follow up with a quick tip video.
If you liked this write-up and want the full hands-on walkthrough (with all the noises, mistakes and fixes), watch the full video and don’t forget to like and subscribe on YouTube
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