Matt is a professional painter and freelance writer, sharing his knowledge, house-painting tips, and product reviews.
Using Masking Liquid on Glass
When painting wood around glass, whether it's a French door or window sash, your options are to carefully cut-in with an angled paint brush, tape off the perimeter of the glass, or use masking liquid instead of tape. Regardless of the method you choose, painting around glass is a time-consuming obstacle, but masking liquid can make the process faster when used correctly.
Masking Tape vs Liquid
Since I spray most of the French doors and windows that I paint, I have to mask off the glass for over-spray, but tearing off a million pieces of tape and fitting them into every corner of the glass isn't fun when you're masking multiple windows, especially French doors.
I've masked off windows so many times in my painting career that I can do it pretty fast, but for someone without any masking experience, it's going to take a lot longer, and this is where masking liquid saves time. I've always taped off windows with Frog tape and paper, but I used the H20 masking liquid on a couple French door projects and I wanted to share my experience using this product.
Applying H20 Masking Liquid
The consistency of the liquid is similar to paint, but it brushes on easier with very little spatter. The liquid is white in color, but it dries to a clear, rubbery film that peels off when fully dry. You can use this stuff indoors and outdoors, but I've only used it indoors on French door glass. I didn't notice any strong odor while working with this product.
I cleaned the glass with Windex before applying the masking liquid. The French door wood was cleaned and sanded too prior to application.
Cutting-in the Liquid
This product is a water-based, modified acrylic. You can brush it on or even use an airless sprayer. I covered several French door windows with this product, using an angled paint brush. I used my sprayer to apply the primer and paint, so I had to completely cover each of the windows for over-spray protection, but if you're painting with a brush, you only have to apply a narrow strip of liquid where the glass meets the wood.
When cutting-in with this product, the liquid pulls off the glass if you brush over one spot too many times. You have to brush on the liquid in one heavy pass and leave it alone. One thick coat makes it peel off a lot easier at the end. If you apply too thin of coating, the film becomes brittle and less flexible for removal.
The white liquid starts to turn hazy and dries somewhat clear about five minutes after application. I let the film dry overnight before spraying my primer.
Does the Film Peel Off Easily?
Applying a thick coat over the glass is a must. This prolongs the drying, but the thicker coat makes the film more rubbery and flexible for easy peeling when dry. I made the mistake of applying too thin of a coating on some of the windows, which resulted in me having to use a razor blade on parts of the glass. I also sprayed two coats of a hard-drying primer on top and that made matters worse, but both were my fault.
This product peels off glass a lot easier shortly after the wet paint dries to the touch. With one of the doors, I waited until the day after painting to remove the film, but the paint and primer had hardened, making removal slower.
Since I was spray painting the French doors, I had to remove the film from the entire length of each window, but removing a small strip around the perimeter of the glass would be very easy. To peel off the film evenly, score the edges of the window glass with a razor knife.
With French door glass, regardless of using tape, or masking liquid, it's hard to get perfectly straight lines along every edge, especially on older doors, but a razor blade comes in handy for evening out the edges.
Is Masking Liquid H20 Worth Using?
Having masked hundreds of windows and doors in my painting career, covering glass with Masking Liquid H20 is definitely faster than using painter's tape or cutting-in multiple coats. The only coat you have to cut-in is the masking liquid.
Cost wise, you'll spend more money on a gallon of this product than you would for a couple rolls of masking tape, but you're going to save a lot of time, especially if you're painting French doors. Those aren't fun to paint.
In order for this product to work correctly on glass, you have to apply a very thick coating so the film is more stretchable for peeling. Apply a narrow strip of the liquid on the glass wide enough for your paint. I would also recommend skipping primer that dries too hard otherwise the surface could become too brittle and less flexible for peeling.
Protecting metal when using this product is important too because direct contact with the liquid can cause corrosion. I would also avoid using this product on frosted, or colored glass, to prevent potential damage upon removal. I have only used this product on clear glass.
This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.
© 2020 Matt G.