Seam sealing actually necessary?

Not unless you are scared of droplets of water. Sometimes I will just dab a couple spots with seam seal instead of overdoing it.

Do you need to? I think you would have to test it in the rain to find out.

If MLD recommends it, than it's probably best to do it, using whatever method(s) they suggest. It's all about comfort/risk-management.

Before the days of taped seams, a handful of tent manufacturers used hydrophilic thread to reduce the probability of water infiltration when the seams got wet. But it's overall effectiveness had as much to do with the quality of the sewing as the thread itself, so results would vary. Having personally owned several of these types of tents, I only started having leaking issues on one of them this past summer, after 19 years of use. I have since applied seam sealer.

I kinda figured it was as much about reinforcing the seam as it was sealing it. With thinner and thinner fabrics, the stitched areas could be beefed up a bit with a good seal job was what I thought.

Although it's not a Duomid, I was under a Zpacks Cuben hammock tarp with doors that wasn't sealed along the ridge line or the mid panel tie outs in a particularly hard rain in the Santa Cruz Mountains and experienced misting through the sewn through ridge and mid panel tie outs. So in a light rain it may not be necessary but in a heavy rain it certainly is.

I own stuff that doesn't need it – both tarps. So follow the manufacturer recommendations. Oderless mineral spirits will thin out clear Silicone sealer (with a lot of stirring) and makes a great sealer. Also works good for patching holes.

You will need to use a lot, since it's from MLD there's going to be tons of lose threads and it's really sloppy stitching :)

For me it's not worth the risk. I'd be really pissed if all my gear was wet because I didn't spend 30 min seam sealing.

Cold water dripping on your head at 3AM is delightful, let alone soaking your sleep insulation the first night of a multi-day trip.

Set it up in the back yard and turn the sprinkler on it for a few hours with newspaper on top of your sleeping pad. You'll see how much it is needed. Wind can drive water into places that the sprinkler test might miss.

Every tent I've ever owned (about a dozen) has had seam sealer applied. And yes that includes a Duomid and a Cricket.

What if you took your new tent outside and practiced setting it up a few times to get the procedure down, and then try it in a suimulated rainstorm (i.e., under the sprinkler)? You'll get really good at putting it up and tearing it down fast, and you'll also find out whether or not you have to seal the seams. Just my 2¢ worth.

"You will need to use a lot, since it's from MLD there's going to be tons of lose threads and it's really sloppy stitching :)"

Really? I've owned a few products from MLD and always found their stitching to be excellent.

Really good advice. I suspect that seam-sealing is more of a hobby than a necessity nowadays. But the only way to know for sure is to try the gear in the rain, and a sprinkler is a great test. Also, folks need to spend time understanding their gear before they head out into the back country.

I interpreted the closing smiley, combined with my complete satisfaction of my own SilDuo, to infer facetiousness.

I agree Chad, the MLD products I own have excellent stitching as well.

Ahh, OK. I admit I have no idea what the smiley faces mean or why people put them there.

My experience has been that seam sealing is necessary. I have also found that it is important to test it all out with a hose afterwards, to find the bits I missed or that need extra seam sealing. Sealing my Trailstar was fairly straightforward, but get my Cloudburst 3 water tight was major challenge.

Last fall I was in MLD Duomid in a strong thunderstorm in the Winds. After 20 minutes seams on windward side started to leak. The water then would collect on the hooks sewn inside and drip. My bag would be soaked, so I had to pack and wait the storm out crouched in the middle. So, absolutely, seal it. There are some threads here on sealing. Use that automotive silicone stuff people mention. No "spirits", just plain silicone. Not the stuff that comes with Duomid either.

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That reminds me. How do people get Duomids or similar tents as close to the ground as possible? I can not get the edge of the tent closer than about 1-2" from the ground. In a strong wind and rain water gets blown in. When it's windy I also would like to have more sealed to the ground pitch. Perhaps some sort of an inner skirt would help? Thoughts?

"That reminds me. How do people get Duomids or similar tents as close to the ground as possible? I can not get the edge of the tent closer than about 1-2" from the ground. In a strong wind and rain water gets blown in. When it's windy I also would like to have more sealed to the ground pitch. Perhaps some sort of an inner skirt would help? Thoughts?"

Stake it directly through the loops that the linelocs are sewn to.