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Before painting any wood, it’s important that you treat any knots with a knotting solution to avoid any seepage or discolouration of the final finish.
Although you could skip this step and go straight to painting, after a few years you may begin to see the consequences as the seepage from the knots begins to discolour the paint.
To help you choose a suitable knotting solution, our hand-picked selection features top-performing formulas chosen through our first-hand experience treating knots (as shown in the image above), testing and the latest research.
How The DIY Works Team Tests & Rates Knotting Solutions
Whilst changing all the door frames, architraves and skirting boards within a recent house renovation, we took the chance to test a number of knotting solutions.
This involved brushing the formula onto the knots before painting. We also tested the solutions upon an outdoor wooden seating area and so far it’s certainly stopped any seepages from the knots.
Although many people skip this step, we highly advise you don’t because after a year or two, you’ll soon see the seepage from the knots in the wood discolour your paint.
Edward Bailey/DIY Works
As well as testing, we also based our recommendations upon plenty of research and a number of factors. The factors that we considered included their effectiveness, ease of application, compatibility, time to dry and value.
By far the most popular and highly rated knotting solution is by the Rustins brand. It’s designed specifically to seal knots in wood and other timber and it can also be used forinterior or exterior use.
Pure shellac formulation
Large 300 ml bottle
Easy to apply by brush
Suitable for interior and exterior use
During our testing, we found that it required two coats
Overall, the Rustins knotting solution ticks all the boxes and it does exactly what it sets out to do on the bottle, which is of course to seal knots. It isn’t the cheapest formula but it’s definitely worth paying the extra for. We used this particular formula before painting skirting boards and we have no complaints whatsoever.
2. Best All-Rounder: Ronseal Colron Knotting Solution
The Ronseal Colron is another popular knotting solution that permanently seals knots and resinous timber. A unique feature of this particular knotting solution is the fact that it comes with an in pack brush. This has the benefit of less mess and no requirement of a paint brush when treating knots with this solution.
Supplied with a brush for application
Low odour formula
Easy to apply and fast drying
Most expensive per 100 ml
Only suitable for interior use
The Colron knotting solution by Ronseal is a great option to consider that’s highly effective and even comes with its own brush. However, unlike the Rustins alternative, it’s only suitable for interior use and also comes in a much smaller bottle, which means it may be expensive to use if you are treating lots of knots.
Another formula by the Ronseal brand is their Knot Block, which is a wood primer and undercoat solution. According to the brand, it’s everything that you need in a tin and it’s guaranteed to block wood knots.
Primer and undercoat formulation
Permanently seals wood knots and resins
Won’t yellow, crack or peel
Touch dry in 30 minutes
Helps paint stick and last longer
Relatively expensive when compared to the alternatives
To conclude, the Ronseal Knot Block is by far the best knotting solution if you want a base ready to paint onto such as skirting, door frames and architraves. The only drawback is the premium price tag but when you consider that it primes and undercoats, it’s a worthwhile investment that you won’t regret.
One of the cheapest knotting solutions on the market that’s actually worth buying is the Liberon Knotting Pale. According to the brand, it’s suitable for all types of wood and it can be painted upon after two hours.
Touch dry in 15 minutes
Highly effective at preventing seepages from knots
Pale in colour
Suitable for use with clear varnishes
During testing, we found that it output quite a strong odour during the application
Overall, the Liberon Knotting Pale is an excellent all-round option that’s effective and offers great value for the money. Regardless of the type of wood that you treat, you can rest assure that this formula won’t allow any seepage.
5. Best Value Runner-Up: Centurion Patent Knotting Sealer
The Centurion Knotting Sealer is another relatively affordable solution that comes in a large 500 ml tin for treating plenty of wood knots. It’s designed to be used prior to priming and undercoating and it can be easily brushed onto the wood with ease.
Fast drying formulation
Interior or exterior use
Requires multiple coats for the best results
Overall, the Centurion Knotting Sealer is a great option to consider that’s affordable, effective and won’t disappoint.
Although you can go ahead and paint onto wooden surfaces straightaway, you may regret it later on. Wood knots can ruin the completed finish of the top coat and cause discolouration. Therefore, to avoid disappointed, it’s crucial that you treat the wood knots before applying a primer or undercoat. All of our recommendations above are suitable for all types of wood and are very easy to apply.
Written By Edward Bailey
From painting garden fences to mist coats upon fresh plaster, Edward (also referred to as "Eddie") is the specialist when it comes to painting and decorating. He learnt his trade from being a self-employed decorator and painter for five years but he has since moved part time in order to play a role as one of the main authors upon DIY Works.