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How to Waterproof a Black Diamond FirstLight Tent

The Black Diamond FirstLight Tent is a four-season, two-person tent that weighs 2 lbs 9 oz. It’s a single-wall, free-standing tent that is a snap to set up, which is important in freezing weather when you want to get out of your cold damp clothes and into warm dry ones. I’ve been using a FirstLight for nearly 10 years for winter backpacking and camping and haven’t come across any other tent that’s as lightweight and convenient to use.

But the FirstLight has always gotten a bum rap as not being waterproof, even though the fabrics it’s made with are. For example, the current FirstLight’s walls have a hydrostatic head of 1500 mm, while the floor is rated at 3000 mm. That’s is more waterproof than many of the mainstream backpacking or camping tents sold today.

The part of the FirstLight that is not waterproof are the seams, which need to be sealed if you need to use the tent in the rain. Whenever you sew two fabrics together, you create many needle holes and that can leak water when it rains. These seams can be factory seam-taped on conventional tents that are coated with polyurethane, but you can’t seam tape tent walls that are made with silicone-impregnated fabric, like those on the FirstLight. These need to be filled with silicone seam-sealer which can bond with the silicone-impregnated walls. That’s why Black Diamond includes a tube of silicone tent sealer in every new Firstlight tent.

Assemble the materials you need for the seam sealing process

The first step in the seam sealing process is to gather together the materials you need:

  • Silicone tent sealant (1 tube comes with the FirstLight at purchase)
  • 1″ wide foam brush (much easier to work with than the brush included with the seam sealer)
  • Paint thinner (a paint thinner substitute or white gas will also work)
  • Mixing can (a tunafish or catfood can work well)

Caution: Seam sealing should be done is a very well ventilated location, preferably outdoors. When you are finished, you’ll want to let your tent or tarp dry for 24-48 hours. 

Squeeze the silicone sealant into the can and dilute it about 50/50 with paint thinner. Mix well. The paint thinner will thin the silicone sealant so it seeps into the needle holes more readily than undiluted silicone sealant. When mixed, wet the tip of the foam brush and run it slowly along all the exterior, exposed seams on the FirstLight Tent. This includes the seams where thread stitching is visible and where it’s not. There’s no need to seam seal the corners of the bathtub floor since these have been factory seam-taped on the latest FirstLight model.

Brush the silicone mixture onto the seams and let it soak in

Places where you want to focus your attention, are:

  • the roof
  • sidewalls, under the arched poles
  • peaks above the front doors and rear window
  • the seam between the sidewalls and the bathtub floor

If the mixture begins to thicken as the solvent evaporates, you can add more and mix it in. If you apply a little extra to the fabric on either side of the seam, that’s ok too. Seam sealing isn’t a surgically precise process although you want to avoid making a mess. The entire process should take well under an hour.

Seam seal the seams over the arched poles and around the rear window beak

When you’re finished, carefully inspect all the seams and touch up any spots you missed. Then let the tent dry for 24-48 hours, before packing it away or using it in the field.

Once you’ve seam-sealed the FirstLight, it is will be fully waterproof and should remain so for the effective life of the tent.

Disclosure: Black Diamond gave the author this tent for a future review.

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  1. Why doesn’t BD do this before shipping?

  2. In this day and age why would ANYBODY want a SP Tent that is so small and so darnn heavy. 2 lb, 9 Oz…….Geez…..My tents are: Duplex 19.42 Oz…Lunar Solo 24 Oz… SW Tarptent Moment 28 Oz and my Lanshan 2 is a whopping 39 Oz…….. Hi Philip ! 8-)

    • Because it’s a winter tent and far less drafty than the tents you list. Those are really cold tents to sleep in winter, with the mesh between the walls and the ceiling. You couldn’t pay me to use them. It’s also fully freestanding, so you don’t have to stake it out, and wait for your tent stakes to freeze in place so your tent won’t fall down.

  3. I love that I can insert the poles into the tent without having to get inside, myself. You just pop one end of a pole into its pocket at a far corner, push it up and into its near corner. Do that twice, from the outslde entrance, and you will not get any serious weather into the tent.

    Then toss in your gear – all of it – and have yourself a cozy winter nest with room enough to hold all your gear at hand.

  4. Stephen Van Voorhies

    What was the old Bibbler tent made of, wasn’t it breathable as well?

  5. I have purchased the Black Diamond FirstLight tent but have not sealed the seams. I would like to know once you use the sealant does it dry clear or does it remain a darker shade from the tent?

  6. I am a bit disappointed by this article. I thought at first that I actually found a website that was going to enlighten me on how to waterproof my BD First Light tent. I have a BD First light tent that I used on my cross country bicycle trip. The tent worked out great, but I didn’t experience any significant rain storms to check it’s waterproof properties. The following year I hiked the PCT. Prior to doing the PCT I seam sealed the tent. During some initial rain storms I experienced some wetness inside the tent, and I attributed it to condensation, but then I experienced a 12 hour rain and wind storm. Everytime there was a gust of wind I could feel drops of rain fall inside the tent. I placed my rain gear on top of my sleeping bag to help keep it dry. I also was sleeping on an air mattress so that helped keep my sleeping bag dry. Fortunately I was camped on a slight angle and the water puddled at one end. I had to bail water out of the tent several times that night. I figure that there were at least 2 or 3 liters of water that had to be bailed out. After I got back I contacted BD about this, and they told me that the First Light tent is water resistant, NOT WATERPROOF. They told me that it was not meant to be used in a heavy rain environment like I was using it in. They provided me no advice on how to actually waterproof it. Seam sealing it does not water proof it. Needless to say I was very disappointed. I figured that a 4 season tent should be able to handle a downpour of rain, but my tent didn’t. I suspect that if BD tents have a bad reputation for not being waterproof, it is because they ARE NOT WATERPROOF.

    I should have done a little more research before I purchased this tent. Other than it not being waterproof I really like the tent.

    • A Firstlight on the PCT…yeah, you really should have done more research. Really bad choice, if only for the lack of ventilation.

      I think you should read this article about hydrostatic head.

      The Firstlight is waterproof, but not to the level of some other tents, although it is more waterproof than most Big Agnes tents.

      • Hi Philip,
        I guess we’ll just have to agree to disagree.

        My experience with this tent (which was seam sealed) let me know that it is not waterproof. When I contacted BD about my experience, they told me that the First Light tent was not made for real wet environments, like I had used it in.

        The specs on the tent states that it is water resistant. Here is a quote from the BD website: “The canopy is constructed with water resistant, breathable NanoShield fabric.” If this fabric was waterproof, I think that the manufacturer would say so.

        The website link that I had included in my original comment above that reviewed this tent (apparently you removed that part of my comment) also stated several times that this tent is not waterproof.

        I guess in the end, I’m not sure how you can say that this particular tent is waterproof, when the manufacturer doesn’t even claim that, but of course you can say what you want. : )

        • Looks like black diamond has changed their marketing to not claim that the tent is waterproof. Curious. I will reach out to them to see why they changed it and update my content accordingly. I suspect that it’s just because you need to seam seal it, not that the fabric does not meet it’s stated hydrostatic head. In which case my claim stands. You need to look at the hydrostatic head measurement to determine how waterproof a tent is.

    • You mean, you used a product completely contrary to its intended use…and you are complaining about it? You REALLY took this tent on the PCT?? HAHAHAHA!!! Even the author is pushing it a bit, as this tent is primarily designed for an on-route alpine climbing bivy. It’s not a versatile tent, and isn’t intended to be. It’s intended to for alpine conditions and low temperatures, and when the small size and low weight are more important than comfort and storm protection. Get a clue!

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