oily substance in my mortar tubes

[chrish]

after using my new hdpe mortars this year I swabbed my finger on the inside and there is an black oily black substance coating the inside. I figured this was condensation that mixed with the black powder remnants. I figured the water would evaporate and leave a dry residue behind. it hasn't really evaporated.

I am using a swab of paper towels on a drill to wipe them dry for now.

also I have the same issue on some of my fiberglass tubes so I blew an acetylene torch down a couple of the tubes for a second or two. the oily substance dried up and left a hard char product. it is sort of like the product when heater tubes coke up industry. just a hard carbon char left behind. so it will reduce down from a liquid to a solid, but will a little more heat.

my concern is this stuff soaking into fusses next time I use them. I load up several hundred of these per shoot, so they may spend a couple days in the mortars before I am ready for them due to the time it takes to prep 5-600 mortars.

how does everyone else handle this oil black stuff?

[WithReport]

I have 200+ DR11 HDPE tubes. I have never noticed any oily substances. I just went out and checked all the ones I used this year and some of the ones that were not used this year. None of them had any "oily black stuff."

We'll see what others say.

[chrish]

my guess is all three shoots I did with them were after rain storms. humidity was horrible. when the tubes were hot after firing I could see the air inside saturating with more moisture since it was hot. once it cooled this extra moisture would have to condense out and cling to the inside of the tube with the burned powder.that is my theory, but I was expecting a dry powdery black/grey residue.

it has the consistency of wd-40. and black as coal. I may leave a rack out in the sun tomorrow and see it dries (if it will ever stop freaking raining here in eastern ky)

[cptnding]

I've seen it on and in the tubes in my racks many times. Always happens in really high humidity. Humidity is a near constant in GA. I load my racks well in advance as well. Almost every shoot I have one or two (out of 300) shells that the fuse goes out as i it burns between the tube and the canister shell itself. I've often wondered if that was the cause. Even if it is, as long as its minimal failure, it will never justify washing and drying all those tubes. The big concern is always keeping the chain fuse dry and burning.

[chrish]

thank you for the confirmation.
i may join you on accepting a 2-3 percent failure rate.
i am looking to go up to 400 mortars next year and can't see myself cleaning them all.
i may do some testing this week to see how much this stuff affects fuse burn

[Big Worm]

I live in NE and my mortars have been this way also after a show. I store them inside and they seem to always dry out.

[FBpyro]

I found black residue on the inside of my mortar tubes the first day I used em this season as well, I just used a paper towel and shoved it down and used a twisting motion to clean it out. I find that over time the build up on the inside makes the shells a tighter fit.

[Big Worm]

What is the best way to get that build up out?

[Rick_In_Tampa]

I live in the swamp and I've never had this problem with my tubes and I keep my tubes in my garage 24/7/365. I'll be on the lookout from now on though.

[Forti1bs]

I have experienced this too. I live in an area with very high humidity and I believe this is the reason. After a show I tip my guns upside down to clear them out and sometime I even swab them out...