Water-based undercoat paint products and adhesion primers are being used more regularly in decorating. Some people use water-based undercoat before applying an oil-based topcoat. Other people use what they think is the best water-based undercoat for any water- or oil-based topcoat, no matter the finish or brand.
You do need to choose one of the modern undercoats though, otherwise you may experience issues. As a professional Decorator, I have tried and tested just about every undercoat on the market. The products that were launched over the past year or so (at the time of writing this blog), far outperform the older ones.
I thought I’d take a little bit of time to sit down and list three of the very best water-based undercoat paints on the market. Feel free to skip ahead to the part of the blog you need.
The Benefits of Using Water-Based Undercoat
You do need to be careful about which water-based undercoat you opt for, but there are various benefits. I thought I’d quickly list them here before going into my product recommendations.
Better for the Environment
Sustainability is important to me, particularly when painting. Water-based undercoats are far kinder to the environment than the old-fashioned oil-based alternatives. They take less energy to manufacture, contain less harmful chemicals, and the waste is easier to dispose of responsibly.
Quicker Application
Water-based undercoat isn’t just quicker and easier to apply. It also has a shorter drying time, meaning you can apply multiple coats of paint in a day.
Superior Adhesion
This may be hard for some to believe, but the best water-based undercoats have better adhesion qualities than their oil-based counterparts.
Nicer to apply
The first thing that strikes you when you switch to water-based, is the lack of strong odour. This makes working with it more pleasant. Moreover, the flow of water-based undercoat is a lot better, so you can fly through the application.
The Best Water-Based Undercoat Paints
Zinsser BIN Aqua
Zinsser BIN Aqua is a new water-based primer and undercoat, designed to be capable of almost anything. It adheres well to old oil-based coatings and other difficult surfaces. It also blocks stains such as tannins and even stop knot bleed.
You’ll find Zinsser BIN Aqua more than capable as an undercoat for pretty much any topcoat. It’s easy to use and has great opacity. It can be used inside and out too.
You should apply two coats when painting bare timber to block the sap bleed and tannins, but one coat over previously painted surfaces is ample.
Bedec All Prime
Bedec All Prime is the cheaper alternative, but it is just as capable. Like Zinsser BIN Aqua, this undercoat and primer can be used inside or out, and over old oil-based paint coatings with ease. It’s a little bit thinner, so it’s slightly more difficult to strike a straight line with a brush. However, this is the only downside.
Bedec All Prime also contains rust inhibitors, meaning it’s a good water-based undercoat for metal, or exterior wood with nails in it.
HB42 PS2
HB42 PS2 is another modern water-based primer and undercoat that can be used inside or out. It’s gone under the radar a little bit, but it’s a product I use a lot and really rate. The opacity is amazingl! You can just about achieve a full colour change in one coat, which is unreal!
This is the only water-based undercoat on this list that only comes in white. But, as far as performance goes, it’s easily one of the best on the market.
You’ll find it quick and easy to use, seems to go for miles, and makes the perfect base for any topcoat.
Tips for Applying Water-Based Undercoat
You’ve had my product recommendations, but I thought a few tips might be useful too. Follow these and you shouldn’t have any issues.
Follow Recommended Recoat Times
Just because an undercoat feels dry, don’t assume you can paint over it straight away. The manufacture’s recoat times are there for a reason. It might be that the paint is still tightening, or maybe it’s too soft to sand. It may still contain moisture which can get trapped and cause the paint to fail over time. You should never rush drying times.
Do Your Prep
Before applying any undercoat, you should clean and abrade the surface you intend to paint. This doesn’t just help you to achieve a good finish. It also helps the adhesion of your paint.
Use a Paint Conditioner if You’re Painting on a Hot Day
You don’t need a paint conditioner most of the time, but if the product is drying too quickly, then a conditioner can help greatly. It doesn’t just extend the open time of the paint; it also helps reduce brush marks. The conditioner I use is Smith & Rodger Blockade.
FAQs
Can you use water-based undercoat over oil-based paint?
You can, providing the oil-based paint has fully cured, which can take several months with some products. If you try painting it before the oil-based paint has cured, then you will experience adhesion issues caused by solvents escaping the existing paint.
Can you use oil-based topcoat over a water-based undercoat?
Yes, you can use an oil-based topcoat over a water-based undercoat. Just allow the undercoat plenty of time to dry and use quality trade products.
Can you use water-based undercoat outside?
Some water-based undercoats can be used outside. Don’t just blindly buy any undercoat though; opt for one that stops rust and blocks stains. You’ll achieve a good finish either way, but the products that don’t stand up to rust and stains generally fail sooner.
How many coats of water-based undercoat?
One coat of undercoat is all you need unless you’re going for a strong colour change.
Final Thoughts
I’ve seen the industry change a lot over the years. Go back 20 years, and almost no one used water-based on woodwork. In 2010, VOC restrictions brought in by the EU meant oil-based paint had a sudden drop in quality. We were forced to change our habits, but the quality of water-based undercoats were also lacking.
Since then, I’ve seen the adhesion and opacity of these paints improve. Now the best water-based undercoats out-perform oil-based in many areas. Some even block stains, stop rust, and are flexible enough to be used outside.
0 Comments