Benjamin Moore Paint Extender · K518
Hot, dry or windy?
Keep your wet edge.
Benjamin Moore's waterborne extender keeps premium latex paint workable longer, so each pass blends into the last before it dries. Add up to 236 mL per 3.79 L when conditions are tough, then brush, roll or spray as usual.
236 mLmax per 3.79 L
6 g/LVOC, 100% acrylic
$22.70946 mL from
$249+ships free in Canada
For Benjamin Moore premium waterborne paints. Not for alkyd or oil-based paint.
Paint Extender K518Clear · interior and exterior
Work out my doseBenjamin Moore Paint Extender K518, Waterborne
Prix habituel
$22.70 CAD
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Benjamin Moore Paint Extender, K518
Benjamin Moore Paint Extender (K518) is a premium waterborne extender and thinner for Benjamin Moore premium waterborne paints. It extends open time and helps keep a wet edge when brushing, rolling or spraying, especially in hot, dry or windy conditions, without affecting the dry film.
Key Features
- Extends open time and wet edge for interior and exterior latex paint.
- Proprietary 100% acrylic, clear, 6 g/L VOC.
- Brush, roll or spray.
- Add up to 236 mL per 3.79 L of paint when conditions call for it.
946 mL and 3.78 L. For Benjamin Moore premium waterborne paints such as Aura and Regal Select. Not designed to be used alone. Do not mix with alkyd or oil-based coatings.
Specs & Coverage
| Type | Waterborne paint extender |
| Mix ratio | Up to 236 mL per 3.79 L of paint |
| VOC | 6 g/L |
| Application temperature | 4.4–32.2 °C (40–90 °F) |
| Clean-up | Clean water |
Application Guide
- Use it in dry (under 50% RH), sunny or windy conditions.
- Add up to 236 mL per 3.79 L of paint and stir well.
- Apply by brush, roller or spray; clean up with water.
FAQ
1How much do I add?
Up to 236 mL per 3.79 L of paint.
2Can I use it with oil paint?
No. It's for waterborne paints only.
3Does it change the colour?
No, it's clear.
Canada Shipping
- Enjoy free shipping in Canada on orders over $249. Yukon, NWT, Nunavut not included.
Winter Shipping:
- From December to April, shipping outside of Ontario and Quebec is limited.
- Returns accepted within 35 days from the date of delivery.
- Custom tinted paints are classified as Final Sale items and are not eligible for return or store credit.
Why use it
Paint that dries too fast leaves marks.
On a hot, breezy day or in a dry room, latex paint can start to set before you roll back into it. That's when lap marks, brush marks and patchy sheen show up. Extender gives you more time.
01
More open time
Keeps the paint wet longer so you can work into the last pass and keep a wet edge on walls, doors and trim.
02
Doesn't hurt the finish
Benjamin Moore made it to improve how premium paint goes on without affecting the dry film. Clear, so your colour stays the same.
03
Brush, roll or spray
100% acrylic and low VOC (6 g/L) for interior and exterior work. Cleans up with water.
Use with Benjamin Moore premium waterborne paints like Aura, Regal Select and ben. Not designed to be used on its own. Don't mix with alkyd or oil-based coatings. Apply above 4.4 °C (40 °F).
Dose calculator
How much do I add?
Tell us how much paint you're using. We'll show the most extender Benjamin Moore allows: 236 mL per 3.79 L, for dry, sunny or windy conditions.
Mild conditions? Above 50% humidity, out of direct sun and with little wind, Benjamin Moore says you don't need to thin at all.
Add
—
Choose a sizeStir the extender into your paint well before you start. Never add other paints or solvents.
Works with
Made for Benjamin Moore premium latex.
Best colour
Aura
- Good for
- Deep colours and feature walls, where an even sheen matters most.
- From
Busy rooms
Regal Select
- Good for
- Washable walls in hallways, kitchens and family rooms.
- From
Outside
Aura Exterior
- Good for
- Siding and trim on hot, sunny days, when paint dries fastest.
- From
Also works with ben, Regal Select Exterior and other Benjamin Moore premium waterborne paints. Using ADVANCE or another alkyd? Ask us first.
Specs
The details.
| Type | Waterborne paint extender and thinner (K518) |
|---|---|
| Use with | Benjamin Moore premium waterborne paints, interior and exterior |
| Colour | Clear |
| How much | Up to 236 mL (8 fl oz) per 3.79 L of paint, in dry, sunny or windy conditions |
| Apply with | Brush, roller or spray |
| Vehicle | Proprietary 100% acrylic |
| VOC | 6 g/L |
| Volume solids | 4.0% |
| Apply at | 4.4–32.2 °C (40–90 °F), air and surface |
| Dry time | Follow your paint's label |
| Clean-up | Clean water. Mineral spirits rinse for spray equipment |
| Don't use | On its own, or with alkyd or oil-based coatings |
Store between 4.4 °C and 32.2 °C and protect from freezing.
How to use
Mix it right.
- Check the conditions. Hot, dry (under 50% humidity), in direct sun or windy? That's when extender helps. In mild conditions, skip it.
- Measure. Add up to 236 mL per 3.79 L of paint. Start with less and add more only if the paint is still drying too fast.
- Stir well into the paint before you start, and again as you go. Never add other paints or solvents.
- Paint as usual with a brush, roller or sprayer, working from dry areas back into wet paint.
- Clean up with water right away. Give spray equipment a final mineral spirits rinse to prevent rust.
FAQ
Questions, answered.
What does paint extender do?
It keeps waterborne paint wet longer (more open time) and thins it slightly, so it flows out and blends into the last pass instead of drying too fast. That helps you keep a wet edge when it's hot, dry or windy, which is when lap and brush marks tend to show.
How much extender do I add?
Up to 236 mL (8 fl oz) per 3.79 L of paint, and only when conditions call for it. In mild, humid weather (above 50% humidity, no direct sun, little wind) Benjamin Moore says you don't need to thin at all.
Which paints can I use it with?
Benjamin Moore premium waterborne paints, inside or out, like Aura, Regal Select and ben. Don't mix it with alkyd or oil-based paints.
Will it change the colour or finish?
Used at the recommended amount, Benjamin Moore says it improves how the paint goes on without hurting the dry film. It's clear, so it doesn't change your colour. Don't go over 236 mL per 3.79 L.
Can I use it when spraying?
Yes. It works for brushing, rolling and spraying, and it's handy for keeping a wet edge on big walls and ceilings with an airless sprayer.
Does it slow down dry time?
It keeps the paint workable longer while you're applying it. Follow the dry and recoat times on your paint's label.
Is it the same as adding water?
Both thin the paint, and Benjamin Moore allows either up to 236 mL per 3.79 L. Extender is a 100% acrylic conditioner made to extend open time, so it gives you more working time than plain water.
Can I use it in cold weather?
Don't apply it when the air or surface is below 4.4 °C (40 °F), and protect it from freezing.
How many cans will a bottle treat?
At the full 236 mL per 3.79 L, a 946 mL bottle treats about four 3.79 L cans, and a 3.78 L jug treats about sixteen. In milder conditions you'll use less.
Sizes and shipping?
946 mL and 3.78 L. We ship across Canada, free on most orders over $249, or pick up free in Mississauga.
Painting on a hot day?
Not sure if your paint needs it? Ask our team. We've been helping painters and contractors since 1997.