Weatherproofing the pop-top canvas

The elements, be they the unseen harmful rays of the sun or the obvious strong force of wind, take a toll on the integrity of the pop-top canvas over time.  Exacerbating the effects of nature, owners often contribute to the canvas’s demise by accidentally tearing, puncturing the canvas during use or setup, and, unfortunately, by neglecting the buildup of dirt and canvas-devouring mildew.  Being careful with the canvas will help with the former issues and for the latter two, like all bus components, the canvas requires a little bit of attention now and then.

With this in mind, I set out a few months ago to clean and waterproof Moby’s pop-top canvas, which is, amazingly, still the original.  Research about which products work for the old cotton-based material revealed that some modern products are designed for synthetic fabrics and may actually harm natural fiber canvases while others may change a fabric’s color.  Eventually, I decided on 303 (R) Fabric Guard because it is safe for synthetic and natural fibers, is more durable than silicone treatments, does not discolor fabrics, and retains fabric breathability (i.e. helps minimize condensation inside the pop-top). In addition, Fabric Guard comes in a convenient handheld spray bottle and there are many positive comments on VW forums from those who already used the product.  Most marinas and boat shops stock this product, but it can be found in a variety of outdoor related stores, patio furniture shops, camper suppliers, and, of course, online.

The application process was very easy, though one has to be careful not to get Fabric Guard on the paint, rubber, or fiberglass pop-top.  After cleaning the canvas with a mild solution of soap and water and then letting it dry, Fabric Guard is simply sprayed directly on the canvas until uniformly wet.  Depending on the weather, it may take several hours to dry, but in my experience, only a couple hours were required on a cool, cloudy day.  However, this stuff has nasty fumes (the headache producing kind) and should be used in a well-ventilated area or outside.  I read one review written by someone who used it on their trailer camper while on a camping trip.  Let’s just say it was a rough night sleeping in the car for them due the fumes in the camper and I recommend waterproofing several days before use.  I waterproofed outside and returned the bus to the garage after the canvas was fully dry and only found a minimal chemical smell in the morning.  Later in the afternoon, all was fine.

Overall I am incredibly pleased with the result.  The canvas remained as supple as before and did not change color (I did use a test spot before doing the whole canvas, just to be safe). The weekend after I treated the canvas, we went camping – and if the rain was not coming down in torrents, there was a constant, heavy mist floating in the air.  Yet not a drop leaked through the canvas and, in the mornings after chilly nights, no more condensation developed than is usual for four people sleeping in a confined space.  In fact, I spent the weekend looking at the canvas thinking it was not even wet, which was a little disappointing.  I thought the wind blew the rain in such a way that protected the canvas and only discovered I was wrong on the last day when I looked more closely and found the rain beaded up into small droplets on the canvas.  All in all, this project was a great success.

The product of choice.

The product of choice.

The test spot is indistinguishable from the untreated canvas.

The test spot is indistinguishable from the untreated canvas.

Before treating, I taped the bus roof to help protect the paint from drips and rivulets of waterproofing chemicals.

Before treating, I taped the bus roof to help protect the paint from drips and rivulets of waterproofing chemicals.

I used a piece of cardboard to protect the fiberglass pop top.

I used a piece of cardboard to protect the fiberglass pop-top.

After a few sprays, I used some cardboard on the bottom to guard against overspray and spray caught by the breeze.

After a few trigger pulls, I decided to use some cardboard on the bottom to guard against overspray and moisture caught by the breeze.

Canvas sprayed until uniformly wet. I did not directly spray the screens.

Canvas sprayed until uniformly wet. I did not directly spray the screens.

In order to treat the window flaps, I unzipped them and treated from the inside of the bus. Remember those fumes? They were tough for this step!

In order to treat the window flaps, I unzipped them and treated from the inside of the bus. Remember those fumes? They were tough for this step!

The canvas dried in about 2 hours and is virtually the same as before treatment.

The canvas dried in about 2 hours and is virtually the same as before treatment.

Little water beads during found on the last day of our trip. The canvas looked dry all weekend because, essentially, it was - no water penetrated the material.

Little water beads discovered upon closer inspection on the last day of our trip. The canvas looked dry all weekend because, essentially, it was – no water penetrated the material.

 

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