How to Make Mortar Joints Look Cleaner and Smaller
Whether you’re tackling a DIY brickwork project, refreshing an old wall, or preparing brickwork for decoration, clean and neat mortar joints make a substantial difference in the overall appearance of brickwork. This guide explores practical techniques and tips at every stage: from preparation to finishing touches, helping you achieve sharper, cleaner and visually smaller mortar joints.
You’ll also learn about tools, materials, and common mistakes – all presented in clear UK English with helpful tables and checklists.
Note: Where relevant products or services may be useful, one resource you might consider for brick and masonry supplies and advice is https://www.brickmakeover.co.uk/.
1. Why Mortar Joint Appearance Matters
Mortar joints play a significant visual role in masonry. Even if the bricks themselves are perfect, poorly executed or sloppy mortar joints can make the whole wall look amateurish.
💡 Clean mortar joints emphasise the brick colours and textures, while messy or wide joints can distract the eye and make brickwork appear larger and clumsy.
Here are some reasons enhancing mortar joint appearance matters:
- Visual proportionality – Clean, narrow joints frame bricks better.
- Professional finish – Even high-quality bricks can look inferior with bad joints.
- Preparation for decoration – Painting or sealing looks better on neat surfaces.
- Longevity – Well struck and finished joints shed water better and reduce erosion.
2. Understanding Mortar Joints and Sizes
Before trying to make joints appear smaller or cleaner, it helps to understand what mortar joints are and how their size affects visual impact.
| Term | Description |
|---|---|
| Mortar Joint | The gap between bricks filled with mortar. Commonly 10mm but can vary. |
| Joint Thickness | Actual measurement of mortar gap. |
| Struck Joint | Mortar finish where the top edge is pushed back; often casts shadows. |
| Flush Joint | Level with brick surface; offers cleaner appearance. |
| Recessed Joint | Set deeper than brick face; emphasises brick edges. |
Standard Sizes
| Joint Type | Typical Width | Visual Effect |
|---|---|---|
| Standard | ~10mm | Balanced, classic look |
| Thinner | ~6–8mm | Makes brick courses look tighter and more precise |
| Wider | ~12–15mm | More rustic but can look messy if unclean |
Key Insight: While you cannot physically reduce a joint after it’s been built without repointing, you can visually minimise it by finishing and cleaning techniques.
3. Tools and Materials You Need
Before beginning, gather the right tools. Using incorrect tools can worsen joint appearance.
Essential Tools List
| Category | Items |
|---|---|
| Preparation | Stiff brushes, soft brushes, dustpan, water bucket |
| Joint Working | Pointing trowel, joint raker, margin trowel |
| Finishing | Grout bag, jointer tool (various profiles), sponge |
| Cleaning | White nylon brush, mild detergent, water mist spray |
Mortar Materials
- Sand – clean, well-graded masonry sand
- Cement – typically CEM II for UK standard mixes
- Hydrated Lime – improves workability
- Pigments (optional) – colour matching with bricks
4. Preparing Brickwork for a Clean Joint Look
Preparation is the strongest predictor of how clean your mortar joints will look. Take time here and it pays off.
4.1 Removing Old Mortar
If working on old walls, remove loose or crumbling mortar using a joint raker.
✔ Work carefully to avoid chipping brick edges.
✔ Rake back no deeper than 10mm–15mm to prepare for new mortar.
4.2 Cleaning Brick Faces
Dust, dirt and loose particles on brick faces will bond with fresh mortar and make joints look messy.
Use:
- Stiff brush for dry dust removal
- Water mist to loosen deeper grit
✨ Clean bricks result in crisper edge definition once mortar is applied.
5. Choosing the Right Mortar Mix
Mortar consistency dictates how clean joints look.
5.1 Mixing Principles
- Mortar should be plastic and workable — not dry and crumbly, not soupy.
- Always mix to a buttery texture that holds shape on a trowel without slumping.
5.2 Mortar Colour
Mortar colour influences how big joints look. Lighter mortar against darker bricks can visually widen the joint.
| Brick Colour | Recommended Mortar Shade |
|---|---|
| Red | Mid-grey or buff |
| Buff | Light buff or tan |
| Dark Brown | Dark grey or brown-toned |
| Multi-coloured | Neutral grey |
💡 Tailoring mortar colour to brick tones reduces the contrast and makes joints visually less prominent.
6. Techniques for Cleaner, Smaller-Looking Joints
6.1 Proper Mortar Application
Avoid overfilling joints. Excess mortar squashed onto brick faces dries into rough edges and shadows.
✔ Load mortar onto bed accurately.
✔ Remove excess before it dries.
6.2 Joint Striking Techniques
Different joint profiles impact visual perception:
| Joint Profile | Visual Effect | Best Use |
|---|---|---|
| Flush | Smooth, minimal shadow | Best for cleaner look |
| Slightly Recessed | Gentle shadow | Classic style |
| Struck | Deep shadow | Not ideal if visual size reduction is goal |
| Weathered | Slight slope outwards | Good for water shedding but not appearance |
👉 Tip: Flush and shallow recessed joints minimise deep shadows that make joints look bigger.
6.3 Using the Right Jointers
Jointers come in different sizes. A small radius jointer will compress mortar neatly into joint without creating a groove that draws the eye.
- 6–8mm jointer for neat finish
- Avoid large profile tools for clean look
7. Cleaning Mortar Smears and Residue
Even the best mortar work needs clean-up before final set.
7.1 Timing is Key
Cleaning too early — mortar is too soft
Cleaning too late — mortar is set and hard to remove
Ideal window: after initial set but before fully hardened — typically 1–2 hours depending on weather.
7.2 Cleaning Steps
- Dry Brush: White nylon brush to remove dust and fine particles.
- Mist and Sponge: Lightly wet a sponge; don’t soak. Wipe bricks gently.
- Second Brush: After drying, brush again to remove any remaining grit.
7.3 What to Avoid
❌ Wire brushes on fresh joints
❌ Harsh chemical cleaners on new mortar
❌ High pressure washing — removes mortar
8. Advanced Techniques and Finishes
For those wanting extra crisp results or renovation finesse.
8.1 Repointing for Visual Slimness
Repointing is removing and replacing old mortar with carefully struck joints.
Steps:
- Rake old mortar uniformly
- Clean dust
- Pack new mortar carefully
- Finish with desired joint profile
8.2 Colour Wash and Tints
Some professionals apply a colour wash of diluted mortar to even out subtle hues and minimise contrast between brick and joints.
✔ Light, thin wash only
✔ Match to mortar colour
This can soften joint appearance and create a more unified façade.
9. Weather and Site Conditions
Weather affects mortar and joints significantly.
| Condition | Impact | Recommendations |
|---|---|---|
| Hot & Dry | Mortar dries too fast, cracks | Mist brickwork and mortar |
| Cold | Slower set, weaker early strength | Avoid below 5°C |
| Rain | Washes out joints | Cover work area |
| Windy | Rapid evaporation | Wind breaks, misting |
Always adjust work pace and water content to conditions.
10. Common Problems and Fixes
10.1 Bulging or Excessive Mortar on Faces
Cause: Over application or sloppy tooling
Fix: Remove excess immediately with jointer and sponge.
10.2 Joints Appear Uneven
Cause: Inconsistent trowel angles or pressure
Fix: Practice on sample board; maintain even angle (≈30–45°).
10.3 Mortar Stains After Drying
Cause: Not cleaned at correct time
Fix: Lightly mist and scrub with white nylon brush. Repeat next day if mild.
11. Practical Step-by-Step Workflow
Here’s a workflow checklist you can follow.
Workflow Table
| Stage | Task | Tools Required |
|---|---|---|
| Preparation | Remove loose mortar | Joint raker, soft brush |
| Clean brick faces | Water mist, brush | |
| Mortar Mix | Mix correct consistency | Mixing tub, trowel |
| Application | Apply bed mortar | Pointing trowel |
| Insert vertical mortar | Grout bag | |
| Joint Finish | Strike joints | Jointer tool |
| Clean Up | Brush and sponge | White brush, sponge |
| Final Clean | Inspect & final touch | Soft cloth |
12. Material Quantities and Cost Consideration (Indicative)
💷 Note: materials vary by brand and project specifics.
| Material | Typical Unit Price (£) | Amount per m² (approx) |
|---|---|---|
| Cement (25kg bag) | £6.00–£8.00 | 1 bag |
| Sand (bulk) | £5.00–£10.00 | 20–30kg |
| Hydrated Lime (20kg) | £7.00 | 1 bag |
| Pigment (500g) | £4.00–£9.00 | As needed |
Note: Mortar also includes water, and small tools are one-off purchases.
13. Safety and Best Practice
🦺 Safety is essential when working with mortar and masonry.
- Wear safety goggles
- Use gloves (mortar can irritate skin)
- Dust masks when raking old joints
- Keep area tidy to avoid slips
14. Maintenance After Completion
Once joints are clean and set:
- Check after rain to ensure no wash-out
- Brush surface seasonally
- Avoid planting vines or creepers that trap moisture
- If staining occurs, use gentle cleaning only
15. Summary Tables and Quick Reference
Visual Impact Summary
| Technique | Makes Joints Look Smaller? | Easy to Do? |
|---|---|---|
| Flush Struck | 👍 High | 👍 Medium |
| Recessed Slight | 👍 Medium | 👍 Easy |
| Deep Struck | 👎 Low | 👍 Easy |
| Colour-matched Mortar | 👍 High | 👍 Medium |
| Post-cleaning (sponge) | 👍 High | 👍 Easy |
Do / Don’t Quick List
| Do | Don’t |
|---|---|
| Clean bricks before mortar | Wait till mortar fully hardens to clean |
| Match mortar to brick tones | Use very high contrast mortar |
| Work in mild weather | Work in rain or extreme heat |
| Use proper jointer | Use metal scraper on joints |
16. How Lighting and Shadows Affect Mortar Joint Perception
One often overlooked factor in how mortar joints appear is natural and artificial lighting. Even well-finished joints can look larger or messier depending on how light interacts with them.
Direction of Light
- Side lighting (early morning or late afternoon sun) exaggerates shadows, making joints appear deeper.
- Front-facing light reduces contrast, helping joints look flatter and smaller.
This is why recessed or deeply struck joints can look dramatically different throughout the day.
Surface Texture and Reflection
Rough mortar surfaces scatter light unevenly, drawing attention to joints. Smooth, compacted mortar reflects light more evenly, blending into the brickwork.
💡 Tip: When finishing joints, aim for a slightly polished but not glossy surface. This subtle smoothness helps reduce shadow depth without making joints look artificial.
17. Making Existing Mortar Joints Appear Smaller Without Repointing
Full repointing isn’t always necessary. In many cases, you can improve the appearance of existing mortar joints using non-invasive techniques.
Gentle Surface Refinement
Light abrasion using a nylon masonry pad or stiff brush can remove surface roughness and sharp edges that visually widen joints.
Steps:
- Brush joints when fully dry
- Focus on raised mortar edges
- Clean dust away with a soft brush
This process softens the joint outline and creates a more uniform appearance.
Blending and Tonal Adjustment
Where mortar colour varies across a wall, the eye is drawn to inconsistent joints. Subtle blending using diluted mortar slurry can unify tone and reduce visual noise.
✔ Use the same mortar colour already present
✔ Apply sparingly and evenly
✔ Avoid thick coatings that obscure brick texture
18. Brick Type and Its Relationship to Mortar Joint Size
Not all bricks behave the same visually. Understanding how different brick styles interact with mortar joints can help you choose the best finishing approach.
Brick Texture Matters
| Brick Type | Mortar Joint Impact |
|---|---|
| Smooth facing bricks | Highlight joints more clearly |
| Handmade or rustic bricks | Naturally disguise joint lines |
| Wire-cut bricks | Sharp edges demand neater joints |
| Reclaimed bricks | Forgiving but inconsistent |
For smooth or wire-cut bricks, cleaner and tighter joints are essential because any inconsistency is immediately noticeable.
Brick Colour Variation
Bricks with heavy colour variation already attract the eye. In these cases, keeping mortar joints understated prevents visual overload.
💡 Rule of thumb: The more character the brick has, the quieter the mortar joints should be.
19. Using Joint Consistency to Improve Overall Wall Balance
Consistency is often more important than perfection. A wall with uniformly sized and finished joints will look cleaner than one with technically correct but inconsistent detailing.
Horizontal vs Vertical Joints
Vertical (perp) joints are more noticeable when inconsistent, especially if they vary in width or depth.
Best practice:
- Keep perp joints slightly tighter than bed joints
- Avoid overfilling vertical joints
- Tool vertical joints last for consistency
Course Alignment
If mortar beds vary in thickness, brick courses appear uneven, exaggerating joint size even when they’re within tolerance.
✔ Check alignment every 3–4 courses
✔ Adjust mortar thickness early, not later
✔ Never compensate with extra mortar at the joint face
20. Long-Term Appearance: Keeping Mortar Joints Clean Over Time
Once mortar joints look clean and refined, maintaining them ensures they stay that way.
Environmental Factors
Pollution, algae, and general weathering can darken mortar joints, increasing contrast and making them appear wider.
Preventive steps:
- Light annual brushing
- Avoid splashback from soil or paving
- Ensure good drainage around walls
Minor Touch-Ups
Small cracks or chips can catch dirt and shadows, exaggerating joint size.
Quick fixes:
- Spot-fill with matching mortar
- Compact and flush carefully
- Clean surrounding brick immediately
What Not to Do
❌ Don’t paint mortar joints individually
❌ Don’t seal over dirty joints
❌ Don’t use harsh acid cleaners regularly
These actions often make joints more prominent rather than less.