Humidity vs. Layout - Are You Tracking It?

[C855B]

Is anybody else keeping tabs on the humidity in their layout space?

Where we live in southern Illinois is especially known for its sultry summers. Aside from constructing the layout entirely from non-wood materials (steel studs and pink foam), also I put one of those new "smart" thermostat gizmos in my train room. So, so far I have about a year's history of temp and humidity. I am finding that even with the thermostat's advanced over-cool mode where it tries to control humidity by running the A/C longer, still, the room is now holding 60-65% RH. From renovation work over the past five years*, I have a hunch the problem is the concrete slab wanting to "sweat" from the moist soil underneath.

* - Including the demolished apartment building next door. The basement could have up to a foot of water in it just from groundwater seepage. One of the many reasons we gave up on renovations.

The problem I am having with the layout is a black crust that develops on the rails, and it is only in the past few weeks. There were no issues, or very few, through the fall and winter. I can correlate it approximately to the seasonal weather change and the recorded humidity levels in the space. The black stuff won't budge with contact cleaner alone, it takes 2000-grit sandpaper to polish the rails back into operation. I only really noticed it this spring because I didn't have enough track down last year at this time to observe the effect. I would really, really like to not have to do this kind of ongoing polishing process, because it is beyond the ability of any track-cleaning train, and I am especially concerned about the risk to planned scenery and trackside details from the repeated physical efforts to scrape the crust off.

I've read a couple of posts in online forii connecting humidity levels to nickel-silver rail corrosion. So, I am curious where the threshold is. 40% RH? 50%? 53.872%? I know at >60% I have problems, and that we now know I'm going to have to throw money at it in the form of an industrial-sized dehumidifier (24,000 cu. ft.) and the power to run it. Anybody have a ballpark where the magic number might be?

[Scottl]

If it is the concrete, that can be solved with a barrier coating. That is a much better solution than powering a larger dehumidifier as it solves the problem, not the symptom.  A simple test is to tape a square of vapour barrier over the concrete and leave it.  You'll see condensation if that is the issue.

I have data loggers operating in my house (obsolete for work, but good enough for home).  I have a pretty steady 50-65% RH in my basement, with and without the dehumidifier.  Temp variation is about 4 deg C over the year.  I built my layout with pretty much all wood and have never seen a hint of deformation or other humidity effect.

[Blazeman]

When you poured your slab, was there a vapor barrier in place? Although I have  doubts if they are truly effective.

My phenomena is that I create shocks during the winter whenever I walk across the room and come in contact with the track. Leather soles, rubber soles, composite soles. Flooring is squares of interlocking tiles with a plastic base sitting on a vapor barrier on top of the concrete. I worry about possibly affecting decoders with that situation.

[C855B]

Yeah, I knew there were enough scientists (and/or the insufferably curious) on this forum to help think on this.

Floor coating is already in place - that impossibly-polished look you see in the big photos of the space. We know the old part of the slab has no vapor barrier underneath, we had surface condensation on moister days during build out. The new slab has a barrier. There has been no visible condensation on the old slab with the coating - but I'll confirm how good the barrier is with your test.

I have one more possible to-do, positive ventilation of the attic space. I don't really have much hope for this since the ceiling tiles were a barrier type, and it has barrier insulation above it. "Climate" difference between conditioned space and up top is remarkable.

It's possible to run the A/C at meat-locker levels to control the humidity. The over-cool function drops RH quickly, but temperature, too, so it gets too cold too fast, cycling much more than it would maintaining temperature alone. My thinking at the moment is unless there's a "do'h!" I've overlooked, the solution has to be dealing with the symptom since we've reasonably addressed the cures. You've basically confirmed the threshold for the track corrosion problem is somewhere in that 50-60% range.

[davefoxx]

The problem I am having with the layout is a black crust that develops on the rails, and it is only in the past few weeks. There were no issues, or very few, through the fall and winter. I can correlate it approximately to the seasonal weather change and the recorded humidity levels in the space. The black stuff won't budge with contact cleaner alone, it takes 2000-grit sandpaper to polish the rails back into operation. I only really noticed it this spring because I didn't have enough track down last year at this time to observe the effect. I would really, really like to not have to do this kind of ongoing polishing process, because it is beyond the ability of any track-cleaning train, and I am especially concerned about the risk to planned scenery and trackside details from the repeated physical efforts to scrape the crust off.

I can confirm that I had similar results on Atlas Code 55 nickel silver track in my basement over the last five years.  During the spring, summer, and fall months when I'm not running our oil furnace, I have to run a dehumidifier in the basement.  When the heat's on in the winter, the humidity of the basement is much better, and I give the dehumidifier the winter months off.

When I first moved into the house, before I bought a dehumidifier, I felt like my track had to be cleaned almost daily!  My basement is fairly dry (there's not even a sump pump in the crock) but it gets humid.  Once I bought the dehumidifier, I still needed to clean the track at least weekly.  During the winter months, I clean the track much less often.  I use a Bright Boy by the way.  I believe that there is a direct correlation between humidity and Atlas Code 55 track (I don't use Code 80, so I don't know the effects there).  I do know that what little ME track/rails that I had on the layout was not affected as much, and a pile of Kato N scale Unitrack that I recently pulled out of a box (stored in the basement) and haven't used (or cleaned) in five or more years was as good as the day I bought it.  Oh, and the Kato HO scale Unitrack that's been in my basement since last August has never been cleaned, either, and it works fine, too.  Go figure.

DFF

P.S. Oh, and if I had to guess at the magic number of RH re nickel silver oxidation, I'd say less than 60% is okay and less than 50% is optimal.

[basementcalling]

I was told once that using abrasives on track that will leave scratches increases the surface area, thus starting a cycle where you must increase the frequency of cleanings because you now how more rail exposed to the air to corrode.

Just run trains all the time.

[davefoxx]

I was told once that using abrasives on track that will leave scratches increases the surface area, thus starting a cycle where you must increase the frequency of cleanings because you now how more rail exposed to the air to corrode.

I've used a Bright Boy for years, and that is not my experience.  I believe humidity is the number one culprit on my track.  I'm curious to see how Atlas HO scale Code 83 fares when I get that installed.

Just run trains all the time.

I know that's tongue-in-cheek, but there probably is some truth to that.  However, it's not practical to run trains twenty-four hours per day, and, even if you wanted to, that's really only going to affect your mainline.  Sidings and yards don't see that kind of traffic.

DFF

[wazzou]

Just run trains all the time.

I bet Victor never had to deal with dirty track.   

[C855B]

I was told once that using abrasives on track that will leave scratches increases the surface area, thus starting a cycle where you must increase the frequency of cleanings because you now how more rail exposed to the air to corrode. ...

I hold to that belief, too, which is why I mentioned 2000-grit sandpaper. That's awfully close to a polish. BrightBoys, despite the rubberish binder, are fairly coarse, and leave striations in the metal roughly equivalent to 200-grit or so.

Now, that said, I could very well be inducing a polish-corrode-polish-etc. cycle with this process by exposing virgin metal on each polishing. OTOH, I've been using this method from the beginning, where the first thing to happen after track goes down is to polish off the oxidation from several years of storage, in some cases. Only this spring have we had issues.

I can confirm that I had similar results on Atlas Code 55 nickel silver track in my basement over the last five years. ... I'd say less than 60% is okay and less than 50% is optimal.

Thanks! I'm mostly M.E. Code 55, but am starting to catch rail-top corrosion on Atlas turnouts. Now I'm really curious... the small amount of Code 40 I have down right now doesn't seem to have the crusting problem. There could be other factors there, but... still...

[peteski]

Mike, can you take a really close macro photo of the "black crud"?  I'm curious about how it looks. There are also different nickel-silver alloys (probably used by different track manufacturers). Some might be more resistant to oxidation than others. But of course, this is a moot point.

While I really hate to say and I'm cringing now, you might consider using an oily coating on your track. Think Wahl clipper oil or, um, transmission fluid. Even the NoOxID is an oily substance.  Some modelers swear those work miracles on the track. One thing for sure is that oil will create a barrier for moisture and oxygen.  But it will probably attract dirt and gum up the wheels. While I never thought a would recommend this method, it is worth a try.

[Chris333]

It rained yesterday and all night here. I just got 56% in my basement.

[randgust]

I track mine carefully because I've found that resin casting is incredibly sensitive to humidity - above 62% and you can forget it.

My layout room is in the basement with a vinyl floor over the concrete, and a dehumidifier for the summer.   I never let it get to 70%.  I've also got a big collection of books and photos in the room, that concerns me more even than the layout.

There's a real 'sweet spot' on heat vs. humidity that if you try to dry it out too hard you create enough waste heat that you can't stand to be in it.   My sweet spot in the summer is about 68% that I can hold and keep the temperature comfortable.

[peteski]

I track mine carefully because I've found that resin casting is incredibly sensitive to humidity - above 62% and you can forget it.

There's a real 'sweet spot' on heat vs. humidity that if you try to dry it out too hard you create enough waste heat that you can't stand to be in it.   My sweet spot in the summer is about 68% that I can hold and keep the temperature comfortable.

But you don't cast resin in the Summer, correct?

[C855B]

It looks like we can't avoid installing a dehumidifier if the expectation is maintaining humidity below 60%. Plotting the entire history (117505 data points!), what was quickly apparent was the "noise" in the plot correlating to A/C operation. Sure enough, the A/C would dehumidify quickly, but as soon as it reached temperature, humidity would jump back up almost immediately to 75-80%.



You can see the noise as well - again, A/C operation - when over-cool was enabled earlier this month. It's hard to tell from the plot alone if we're fighting peak RH versus average RH. However, loosely associating rail oxidation/corrosion/whatever-the-hell-it-is seems to point at peaks >60% if not average >50%.

I can't rely on the over-cool function for long. The other tenant in the space is complaining about the chill.

One positive here is noting the low humidity through the winter, the lows induced by heat operation. If I hadn't adopted humidity-resistant construction, with as much linear benchwork as there is it would have been shrinkage hell. George Costanza knows the problem.

[learmoia]

It looks like we can't avoid installing a dehumidifier if the expectation is maintaining humidity below 60%. Plotting the entire history (117505 data points!), what was quickly apparent was the "noise" in the plot correlating to A/C operation. Sure enough, the A/C would dehumidify quickly, but as soon as it reached temperature, humidity would jump back up almost immediately to 75-80%.



You can see the noise as well - again, A/C operation - when over-cool was enabled earlier this month. It's hard to tell from the plot alone if we're fighting peak RH versus average RH. However, loosely associating rail oxidation/corrosion/whatever-the-hell-it-is seems to point at peaks >60% if not average >50%.

I can't rely on the over-cool function for long. The other tenant in the space is complaining about the chill.

One positive here is noting the low humidity through the winter, the lows induced by heat operation. If I hadn't adopted humidity-resistant construction, with as much linear benchwork as there is it would have been shrinkage hell. George Costanza knows the problem.

One thing I heard was that living in the mid-west with Corn and Soybeans everywhere.. that the farming process 'artificially' raises the RH 10-15% from where would otherwise be..

After installing my Ecobee, I haven't noticed any effect using over-cool dehumidify..

If your reading your Ecobee Data for this chart, I did notice that my Ecobee Humidity is 5-10% above the rest of the readings from the little digital readers I have (not the Ecobee sensors, I haven't set those up yet.. (doing that in the new house).

Meanwhile in the basement.. with the dehumidifier running in the middle of the train room.. Have the dehumidifier set to maintain 50%, and it cycles on and off all the time.. but the digital readers at outside points of the train room show the 24 hour range between 51-53%

~Ian