jukebox Posted June 18, 2013 Share Posted June 18, 2013 I posted about this in my layout thread, but wanted to raise it here in the per-way area, to see if anyone else has seen this before - or can suggest a remedy. I have been gluing brand-new factory-fresh-out-the-box flex track down on my layout the last few weeks, and it has become apparent that there is a reaction going on between the PVA and the rails, leading to rapid (i.e. overnight) oxidation of both steel (C+L) and nickel silver (Peco Code 70) flex. The trackbed is plywood, with 3mm Depron foam attached to it using dilute PVA. The track is then stuck down onto the the Depron using a thin layer of neat PVA for 3-4 cribs very 100mm. The track is lightly weighted down over night, and this is the sight that greets me 24 hours later: The NS is similar, if less severely affected: This is the guilty party: I know the atmosphere in the room is not the culprit - the tracks get laid out for a week before I glue them, with no reaction. It's not the Depron on it's own - otherwise the oxidation would not be only above where the glue has been spread. It's not moisture on the rails themselves - I schmear a thin layer of PVA on the Depron, then place the track on that. Nothing contacts the actual rails. I have Googled PVA glue, and in some metalworking forums there are references to the fumes generating localised oxidation on steel, but I am surprised that this seems so aggressive, and that it hasn't been discussed at RMWeb before (I searched, and I could not see any obvious references). The steel oxide does brush off quite easily with a cloth+solvent - but I am worried it will continue to return until the leaching fumes abate. Painting or brushing a layer of varnish over the top may be needed. Of course that won't help when it comes to ballasting. I don't fancy using an acid-based rust removal fix (phosphoric acid flux, for instance) for fear what long-term damage that solution might create. The NS oxide is a lot less aggressive, but much harder to remove - it makes a yellowy tinge when buffed with a cloth, but leaving most of the patina behind. I have not energised the track yet, so am not yet able to comment on the effect these oxides have on conductivity, but clearly it can't be improving current flow! I'm due to get some samples of 3mm EVA foam shortly, and so will experiment with test lengths of track glued to them, and with track glued directly to plywood, to see if I can find a less reactive way to secure my per-way. Interested to hear if anyone has experienced this before, and if so, if they found a remedy. Cheers Scott Link to post Share on other sites More sharing options...
kandc_au Posted June 18, 2013 Share Posted June 18, 2013 Scott, If no-one in the UK has this issue it must then be something peculiar to Oz, as I have the issue in Victoria as well. NO, I haven't found a fix for it either. I have been using C&L Track. Khris Link to post Share on other sites More sharing options...
Grovenor Posted June 18, 2013 Share Posted June 18, 2013 What are you using to weight the track down while the glue sets? I have seen similar effects but only under the weights where I have noted that the drying time is longer. I suspect the vapour is being held under the weight. Now I monitor the setting process and remove the weights as soon as the track is held. However, I have not had any long term issues from this, its just a minor irritant. Keith PS. might be worth setting up a fan to blow the fumes away while the glue is setting, although I haven't tried that, not been a big enough problem for me. Link to post Share on other sites More sharing options...
jukebox Posted June 18, 2013 Author Share Posted June 18, 2013 Scott, If no-one in the UK has this issue it must then be something peculiar to Oz, as I have the issue in Victoria as well. NO, I haven't found a fix for it either. I have been using C&L Track. Khris Hi Khris - I wondered if it wasn't a humidity issue that means the fumes leached faster (being part of the house, the room is quite dry). Amazed that it bloomed so quickly, really - esp as I've had the loose track out for almost a month and not seen a spot of oxide. What are you using to weight the track down while the glue sets? I have seen similar effects but only under the weights where I have noted that the drying time is longer. I suspect the vapour is being held under the weight. Now I monitor the setting process and remove the weights as soon as the track is held. However, I have not had any long term issues from this, its just a minor irritant. Keith PS. might be worth setting up a fan to blow the fumes away while the glue is setting, although I haven't tried that, not been a big enough problem for me. Hi Keith - I used construction lumber (4x2's) laid on the track, so yes, if vapour is rising, this would possibly trap it around the rails as it overhangs by 14mm or so. I might try with tinned food cans, placed where there isn't glue, and see if that helps - but I think your fan idea is a winner, and also want to, if you'll pardon the poor pun, give that a blast! At least it does not seem to be re-appearing: the areas I cleaned last night seem to have remained so. Still, I think I will see if a latex adhesive is any better - mind you, the comments about chlorine smells and Copydex suggest it may be just as problematic... Cheers Scott Link to post Share on other sites More sharing options...
RMweb Premium kevinlms Posted June 18, 2013 RMweb Premium Share Posted June 18, 2013 Interesting. I had a similar problem years ago, in my case a section of double track about half a metre long. It went green. I was under the impression that is was because I added washing up detergent to it & perhaps too much. I never did reproduce it, despite using Selleys PVA from the same bottle several times later and using the same technique. Perhaps it was a random result as a result of humidity conditions? Or else it somehow reacted with the brass component in nickel silver track - it was code 75 plain track. I really don't know why. I'm in Melbourne, so perhaps its something in the formula of Aquadhere? Link to post Share on other sites More sharing options...
Campaman Posted June 18, 2013 Share Posted June 18, 2013 A long shot but could it be moisture being drawn out of the lumber you are using as weight. Link to post Share on other sites More sharing options...
Kallaroonian Posted June 18, 2013 Share Posted June 18, 2013 I have had the exact same problem (also in Perth). I'm using code 75 rail in n/s. I'm painting the sides of the rail though so despite having seen these effects I'm not bothered about it. Provided the top of the rail is clean it will conduct fine ie any surface effects in the form of etching or corrosion aren't going to prevent the rail conducting electricity. I agree it does look odd after the track has set in place though - on the n/s as you say a green or yellowy tint. rgds Link to post Share on other sites More sharing options...
meil Posted June 18, 2013 Share Posted June 18, 2013 Under certain conditions PVA can produce acetic acid. Do you have anything alkaline knocking about nearby? This might be your problem. I suggest good ventilation. Link to post Share on other sites More sharing options...
Doughnut Posted June 20, 2013 Share Posted June 20, 2013 I have recently been laying Peco code 100 N/S flexitrack and after setting the ballast with PVA-Water-Washing up liquid drops, I have found that the N/S rail is tarnished with brown stains on the railhead, up and down the track,. It does come off with a track rubber but can come back. Track that has not been in contact with PVA/water mixture is un-tarnished, in the same room. Dave K Link to post Share on other sites More sharing options...
jukebox Posted June 22, 2013 Author Share Posted June 22, 2013 Just a quick update on this issue. I glued some more track yesterday, and followed Grovenor's advice on using less enveloping weights, and also having a small fan blowing overnight to keep the air circulating. The set up looked like this: Vegetarian's paradise - tomatoes, chick peas... This morning, I checked the track - no oxidation at all: So ar least I now have one way of taming the problem. The EVA foam has arrived, so I will still do those tests - will add to this thread when I have the results. Thanks all for your interest and guidence. Cheers Scott Link to post Share on other sites More sharing options...
DadExtraordinaire Posted July 5, 2013 Share Posted July 5, 2013 Hi, I have read somewhere online that PVA can oxidise metals - I believe wargamers have experienced this problem as well. Link to post Share on other sites More sharing options...
Theakerr Posted October 2, 2013 Share Posted October 2, 2013 This thread, found after a search, supports my theory about a problem on a friends under construction layout. He has a test section of code 75 NS track test laid directly onto the plywood base and it has worked well for over a year (DC). We have just finished laying a new section that we only want to do once due to basement limitations. So the fabrication is "complete", i.e bus-bar, cork underlay, painted baseboard etc. We started out with 3/4 plywood and after much cutting we painted it on both side with an oil based paint. Very shortly after drying we completely covered the running side with cork that was glued down using Le-Pages contact cement. note we had to put two coats of cment onto the cork to seal it. Track from the same box as the test section was then attached to the cork using wide headed screws. All operations were completed in his well ventilated forced air heated dining room. Last week we finally got around (after the summer poor skiing break) to installing the completed section around the back of his furnace. Believe me you only want to do that once unless you work for the circus as a contortionist. Anyway after connecting up his test section to the new section, the locos would run as far as the new section and stop dead. After much thought!!! my friend experimented by cleaning an easily accessible section of track with a track rubber and you can guess the result. The locos ran on the cleaned track section and now stopped a bit further in on the non cleaned section. We had tested the track electrically using miniature crocodile clips and point probes and we got current, so the surface layer must be very very thin. We had checked the rail surface with the old finger test and nothing, i.e no black carbonaceous crud and no improvement in running so the surface layer must be tough. We did rub the surface with a bit of track cleaner and got a yellowish tinge to the cotton bud but no improvement in running. Anyway, we ended up hypothesising that either the paint or the glue (most likely) was out-gassing fumes that were oxidising (I am presuming it is an oxide) a very thin surface layer. Found it hard to believe because all work was done in a largish well ventilated room where the air was moved due to the forced air heating. After some contortions we got the entire section"abrasively" cleaned and we now have full operation. We have also cleaned a section of track using a track cleaner that as well as cleaning off carbon crud is supposed to improve electrical conductivity. I will report on the impact of this, if any, later. p.s. we live in Canada Link to post Share on other sites More sharing options...
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