How Do You Add Colour to Mortar?
Mortar—often overlooked—is a key visual element in brick, block, and stone construction. When you change the colour of mortar, you transform the appearance of an entire wall or façade. This guide covers the why, when, what, how, costs (pound-based), mixing methods, common issues, best practices, and special effects you can create.
At its core, colouring mortar involves adding pigments or dyes to the mortar mix before it sets. Colouring mortar is used for restoration, aesthetic enhancement, or to ensure harmony between old and new work. It’s both an art and a science.
Why Add Colour to Mortar?
Mortar colour has a big effect on the appearance of masonry. Colour impacts contrast, harmony, and style.
Visual Impact
| Mortar Colour | Effect |
|---|---|
| Light (e.g., white/cream) | Makes brickwork stand out; crisp, modern look |
| Dark (e.g., charcoal/black) | Subtle wall texture; can make bricks pop less |
| Mid-tone (e.g., traditional grey) | Classic look; balanced contrast |
| Complementary (matching brick tones) | Seamless, integrated appearance |
💡 Tip: Mortar colour is almost as important as brick colour for overall visual effect.
Colour can also conceal repairs, match historic work, or complement architectural details.
What Determines Mortar Colour?
Mortar colour is influenced by:
- Cement type and brand
- Sand type (size, shape, colour)
- Pigments used
- Mixing ratio
- Water content
- Curing conditions
Most DIYers assume mortar is “just grey”, but the shade and tone can vary widely.
Pigments: The Heart of Colouring Mortar
Pigments are concentrated colourants. They don’t affect strength if used correctly. Pigments can be natural or synthetic mineral oxides.
Common Pigment Colours
| Pigment Colour | Typical Appearance in Mortar |
|---|---|
| Iron Oxide Red | Warm red or terracotta |
| Iron Oxide Yellow | Sandy, golden tones |
| Iron Oxide Brown | Deep, earthy tones |
| Black Oxide | Charcoal/black |
| White Cement + Tint | Light, pastel shades |
Pigments must be compatible with cement and free from contaminants that could weaken the mortar.
Source Bricks and Mortar Matching
In restoration or renovation work, matching new mortar to older existing joints demands attention. The colour can change over years due to weathering, pollution, and material ageing.
One practical option in brick matching is having bricks tinted. For example, https://www.brickmakeover.co.uk/ offers brick tinting, letting you match brick colours more accurately while planning mortar shades around them.
Methods of Adding Colour to Mortar
There are three common ways to colour mortar:
- Integral Pigments
- Colour Packs / Pre-blended cements
- Surface Stains / Washes
Let’s explore each.
⭐ 1. Integral Pigments
Integral pigments are mixed directly into the mortar before placing. This ensures the colour is throughout the mortar, not just on the surface.
Steps to Use Integral Pigments
- Measure Pigment by Weight – do not guess.
- Add Pigment to Dry Mix – mix with cement and sand before adding water.
- Mix Thoroughly – ensure colour is homogeneous.
- Add Water Gradually – adjust to workable consistency.
- Place and Tool Mortar as Normal
📌 Important: Always do a small test batch before colouring a large area.
⭐ 2. Colour Packs / Pre-blended Cements
Sometimes pre-blended coloured cements or mortar colour packs are used. These are convenient and reduce the risk of inconsistent results.
| Colour Pack Type | Pros | Cons |
|---|---|---|
| Pre-blended coloured cement | Consistent colour; easy | Limited customisation |
| Coloured mortar packs | Convenient; predictable | Can be expensive |
Example: A manufacturer might sell a “buff coloured mortar pack” that you mix with sand and water.
These products are designed to blend easily and reduce bag-mix variation.
⭐ 3. Surface Stains and Tints
Surface stains are applied after the mortar has cured. They don’t provide integral colour but can effectively tone down contrast or enhance colour.
| Surface Method | Best For |
|---|---|
| Stains / mineral paints | Tinting existing mortar |
| Limewash | Soft, historic look |
Surface finishes tend to fade over time and may require maintenance.
Matching Coloured Mortar to Brickwork
Accurate colour matching is essential. A common mistake is to eyeball pigment additions. Instead:
Step-by-Step Matching Approach
- Select Target Sample – part of existing wall or reference board.
- Create Test Panels – small mortar samples in different shades.
- Cure Samples – let them dry 48–72 hours.
- Evaluate in Natural Light – light changes perception.
- Adjust Pigment Gradually – keep records of ratios.
📝 Record Keeping Table
| Batch # | Cement:Sand | Pigment Type | Pigment % (by weight) | Appearance |
|---|---|---|---|---|
| A | 1:3 | Iron Oxide Red | 3% | Too orange |
| B | 1:3 | Iron Oxide Red | 5% | Closer, too dark |
| C | 1:3 | Iron Oxide Red + Yellow | 4% + 1% | Close match |
This record helps replicate the colour accurately across an entire project.
Basic Mortar Colour Mixing Ratios
Mortar typically uses a 1:3 cement:sand ratio for general use. Adding colour changes the mix slightly.
Example Pigment Ratios
| Target Tone | Pigment % by Weight (of cement) |
|---|---|
| Light Buff | 2–4% |
| Mid Grey | 4–6% |
| Dark Charcoal | 8–12% |
💭 Note: Higher pigment percentages intensify colour but may affect workability slightly.
Mixing Procedure (Step-by-Step)
Below is an easy, repeatable guideline for mixing coloured mortar:
1. Gather Materials
- Cement (e.g., grey or white)
- Sand (correct grading)
- Integral pigments
- Water
- Mixing bucket/tray
- Trowel or mixer
2. Dry Blend First
Mix cement, sand, and pigment dry first. This prevents clumping and ensures even dispersion.
3. Add Water Last
Slowly add water until workable. Too much water weakens mortar and dulls the colour.
4. Test Workability
Mortar should hold on the trowel without slumping.
Special Effects You Can Create
Colouring mortar isn’t just about matching; you can also create visual effects:
Contrast Mortar
Bricks remain their natural colour, mortar is bold.
| Brick Colour | Suggested Mortar Tone |
|---|---|
| Red Brick | Light grey or white |
| Pale Brick | Mid-grey or buff |
| Dark Brick | Charcoal mortar |
This creates a strong grid pattern effect.
Blended Tones
Add small amounts of multiple pigments.
| Pigment Combo | Result |
|---|---|
| Red + Yellow | Warm orange |
| Brown + Black | Deep earthy |
Practical Considerations
Weather and Curing
Mortar colour changes slightly as it dries. Wet mortar looks darker. Once fully cured (7-28 days), colour stabilises.
💡 Wait before final evaluation.
Batch Consistency
Colour varies if you mix small batches inconsistently. Always:
- Pre-measure pigments
- Use the same sand source
- Mix in large batches when possible
Common Problems & Solutions
Problem: Uneven Colour
Cause: Pigment not mixed evenly or water ratio varied.
Solution:
- Dry blend longer
- Use consistent, measured water
Problem: Colour Too Faint
Cause: Too little pigment.
Solution:
- Add measured increments of pigment
- Produce new test samples
Problem: Mortar Too Dark When Wet
Cause: Water lightens colour as it evaporates.
Solution:
- Judge colour after curing
- Expect slight shift
Colour Durability and Maintenance
Colour throughout (integral) mortar lasts longer than surface stains.
Durability Comparison
| Method | Longevity | Maintenance |
|---|---|---|
| Integral colour | High | Low |
| Surface stain | Medium | Moderate |
| Limewash | Low-Medium | Recoat required |
Colours can fade with extreme exposure, but integral coloured mortar is robust.
Calculating Pigment Costs (Example)
Let’s estimate the cost of colouring mortar for a small project.
Assumptions
- Wall area: 20 m²
- Mortar volume required: ~0.1 m³
- Pigment needed: ~6% of cement weight
- Cement weight: 400 kg
- Pigment cost: £6.00 per kg
Pigment Calculation
| Item | Quantity | Cost/unit | Total |
|---|---|---|---|
| Cement | 400 kg | £5.00 per 25kg bag | £80.00 |
| Sand | 1200 kg | ~£0.04 per kg | £48.00 |
| Pigment | 24 kg (6%) | £6.00 | £144.00 |
| Total Material Cost | £272.00 |
Colour adds cost, but the visual effect is often well worth the investment.
Health & Safety
When working with pigments and cement:
✅ Wear a dust mask
✅ Use goggles
✅ Avoid skin contact with dry cement
✅ Work in ventilated areas
Pigments are powders and can irritate if inhaled.
Tools of the Trade
| Tool | Purpose |
|---|---|
| Trowel | Laying mortar |
| Mixing bucket | Combine ingredients |
| Scale | Measure pigments precisely |
| Gloves | Safety |
| Colour charts | Visual reference |
Historic and Contemporary Uses of Coloured Mortar
Mortar colour trends have shifted:
- Historic masonry: often lime-based, varied subtly with sand
- Modern design: bold contrast or matching minimalism
- Restoration: precise matching is crucial
Colour decisions can dramatically change the character of a building.
Summary: Best Practices
✅ Always pre-test colour samples
✅ Record exact mix ratios
✅ Dry blend pigments before adding water
✅ Evaluate colour after curing
✅ Match mortar to brick colour and design goals
Colouring mortar is a powerful way to elevate craft, unify elements, and achieve architectural vision.
Colour Testing: Why Small Samples Matter
One of the most common mistakes when colouring mortar is skipping the testing phase. Mortar colour behaves differently depending on moisture, curing time, and surrounding materials.
Why Test Panels Are Essential
| Reason | Explanation |
|---|---|
| Colour shift | Mortar dries lighter than when wet |
| Light conditions | Sunlight vs shade alters perception |
| Brick interaction | Adjacent bricks influence how colour appears |
🧪 Best practice: Create at least three small test mixes with slightly varied pigment levels. Apply them to spare bricks or a hidden area and allow them to cure fully before deciding.
Using White Cement for Brighter Colours
Standard grey cement limits how bright mortar colours can be. White cement offers a cleaner base that allows pigments to show more clearly.
Grey vs White Cement
| Cement Type | Colour Outcome |
|---|---|
| Grey cement | Muted, earthy tones |
| White cement | Brighter, truer colours |
🎨 White cement is especially useful for buff, cream, pastel, and light grey mortars. Although it costs more—often £12–£18 per bag compared to £5–£7—it can reduce the amount of pigment required.
How Water Affects Mortar Colour
Water content has a surprisingly strong impact on final colour. Too much water dilutes pigment concentration and can cause patchiness.
Water Control Guidelines
| Issue | Result |
|---|---|
| Excess water | Pale, washed-out colour |
| Inconsistent water | Uneven shading |
| Controlled water | Predictable finish |
💧 Always measure water where possible and avoid “loosening” mortar mid-batch, as this can alter colour consistency across joints.
Seasonal Factors and Colour Consistency
Temperature and humidity affect curing speed, which in turn affects colour.
Environmental Effects
| Condition | Impact on Colour |
|---|---|
| Hot, dry weather | Faster drying, lighter finish |
| Cold, damp weather | Slower curing, darker appearance |
| Mixed conditions | Risk of inconsistent tones |
🌦️ Where possible, complete coloured mortar work under similar weather conditions across the entire project to avoid visible variations.
When to Adjust Mortar Colour After Application
Sometimes, despite careful planning, the finished colour isn’t quite right. Small adjustments can still be made.
Post-Application Options
| Method | Suitable For |
|---|---|
| Light surface tinting | Minor tone correction |
| Gentle cleaning | Removing cement haze |
| Weathering over time | Natural softening of colour |
⏳ Mortar often looks harsh when new. Allow several weeks for natural curing and exposure before making changes—many colours mellow on their own.