Mistakes made. Creosote. Now what?

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New Member
Dec 21, 2023
Shenandoah Valley, VA
Short version:
Osburn 3500 Insert with stainless steel insulated liner (installed oct 31st). No blockoff plate. ~ 19foot chimney.

After 1.5 months of good burning, I messed up. During a very cold week (<25F for about 5 days with lots of time in the teens), I burned some wood that was too wet. Glass got all brown and firebricks got ugly. I ordered a soot eater knockoff. but I'm anxious about how shiny and bad this looks!

Have I done damage? Can I fix it? I know that even small amounts of creosote like this cause fire risk -but would you use this before cleaning? I cleaned off what I could using a plastic brush I had - but it's still mostly like the first pic.

Am I over reacting? Even though I think this is mostly the result of the wet wood, could there be other problems?

I stuck my phone down my chimney with a selfie stick.
Pic1: about 6 feet down the ~19ft. chimney.
Pic 2: Top few feet of liner
Pic 3: cap.

Mistakes made. Creosote.  Now what?
Mistakes made. Creosote.  Now what?
Mistakes made. Creosote.  Now what?


I'm pretty anxious because my house is set up for wood heat and it is cold (and expensive) with just the gas. I just paid a lot to upgrade the stove and install the liner. I have started stocking up on wood from my property, but my wood won't be dry until next year minimum.

I know I need to burn dry wood and possibly at hotter temps. I thought it was getting hot enough before this cold snap - I cannot tell you how hot. I don't actually have money right now for a probe thermometer, but I will get one. The thermostat controlled blower came on and stayed on for most of the cold spell.

I bought a house that uses a wood stove as primary/supplemental heating. Not wanting to use the old wood stove - I installed a new Osburn Matrix 3500 on Oct 31st. Things were going really really well: I got dry wood off a friend. I have a moisture meter and checked what I was getting. It was easy to light. I was very warm and happy.

Then, I decided to stop mooching off my friend and buy some wood. I was not vigilant. I was not feeling well, it was raining out. I took possession of the wood and tried to just pick out the dry pieces. But then I wasn't feeling well, and there was a cold snap, and a friend came over for a few days and was chucking wood I didn't check on the fire.

Any advice welcome!
I don't think that looks too bad. Run the sooteater up, clean the cap, get up to temp quick, burn hot, split big splits smaller, don't let it smolder, keep an eye on it... If you have good secondary combustion occuring you should be OK.

First year is a challenge. Try to get 3 years ahead on wood. Creosote can only form at temperatures less than 250 degrees. I figure 200 degrees of temperature loss from the flue probe to the top, so I try to get and keep the probe over 450 until I'm down to coals. There's also varying degrees of unseasoned wood and species. 25% is better than 35%; 25% ash burns OK, 25% oak not so much.
I can’t quite make out what the last picture shows in relation to buildup so I’ll comment on the other pics:
I don’t think that is too bad. It’s a pretty thin layer. It’s is shiny, but pretty thin. If you have better wood available, having more normal temp fires may help convert the shiny buildup to a more degraded form that will be easier the sweep out.
Knock off or not, it’s just weed eater line. Looks like you didn’t run it hard enough for long enough. I have a couple steel brushes. One is real tight, one is not. Occasionally I’ll take the loose one and run it on the drill for a deep clean. That usually gets me back to nearly bare metal. The tighter one will just twist the rods. I wouldn’t do that often as I’m sure there is some erosion happening at some level. I have a straight shot. I also wouldn’t do that in a liner. I only have two pieces of class A, so when it’s time to replace it in 15 years, it probably won’t be that bad.
Almost everyone has trouble their first year.

Pallets are often available for free and they are pretty dry due to their shape and air movement.

Break them down with a sawzall. You can mix wetter wood in with the pallets.
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I assume it's the first year. You burn what you have and keep the stove hot. I plugged and gooed up the screen in my first 2 months. Black glass after ever fire. It all goes away when the wood is 3 years old and kept dry.
You need to do this at least yearley , so get yourself a poly brush and rods and sweep it.