Tracks sinking in Pink Foam

Bill, I tried gently lifting the truck up from the foam but it appears to be imbedded in there.  Afraid of the foam ripping up if I pulled it out of there and possibly destroying the tires if there is a chemical reaction.

 

Just leaving it alone for now to see if there is any further issues.

 

My wife (my scenery builder) just gently reminded me that the foam that was cut out is also glued to the the mountain and the portals and would be a major PIA to simply replace the piece.

 

So i might have to think about propping it up if it gets worse.  Luckily so far it appears to only be this small section.

 

All in all its a learning experience.

I would recommend removing the truck. Simply cut the foam leaving about a 1/4" around the  tires and then cut underneath them and lift the truck out with the foam pieces attached. You can then carefully start removing the foam from the tires by picking or breaking it off. 

 

This will also show you how much and how deep the deterioration is on that piece. One more question. Is that entire piece soft or is it only in selected areas of the piece?  

Then you can patch the holes in the foam from the tires with foam putty.

I agree.I use foam mainly for scenery. But for layout base I have a 1/2" of Homasote on top of 1" of pink foam, on top of 5/8" plywood. With the Homasote glued to the foam there is no chance of the foam compressing and the Homasote holds track screws well. The foam also allows for cutting in rivers and such.

Just as an aside, I have a Lionel flatcar with a diecast combine with rubber tires on it (combine came with the car from Lionel), and they have a piece of thin clear plastic (like model "windows" are made from) set below the tires. I've seen this on other Lionel cars with similar loads. This is apparently necessary to prevent adverse chemical reactions between the rubber tires and the plastic flatcar deck.

If its not spreading, you may want to prop it up now, if your not going to remove it.

  It may stay soft, but it's just as likely it could cure to a rock hard state that would be very much harder too remove & repair later.

 I can't tell what type of scene it is, but "paving" the area if its just parking, would allow a less than perfect chunk to come out , a less than perfect chunk to go in, and some ground cover built up over the gap should look normal butting to the pavement. 

 

 I doubt its anything to worry about here.

But I've had enoughwood finishing rags catch fire in the sun, to always lean to the cautious side with chemical reactions.

 Linseed oil & cotton can catch fire eventually. That's why professional woodworkers  soak their trashed rags, and keep a fireproof garbage can around

 

 

"The tackle box effect" had pretty much disappeared by the mid 80's. But thanks to certain modern Asian production values, its back! What a treat!   

I wonder if edible gummy worms work well and/or if they dissolve too fast 

I have not had this issue with track, but with autos. As the attached photos show, sometimes the tires sink into the latex painted 2" pink Styrofoam. Different rubber wheels seems to react differently. See the two taxis- one is sunken WAY down, the other barely has an indentation. In the motel photo, the truck- a little heavier- is sunken way down, while the convertible is not sunken at all. It took a couple of years for this to become apparent. My train room is temperature and humidity controlled. Oh, and two different brands of latex paint. Makes me go hmmmm.

I decided to remove the truck and see what is happening.

 

Attached are the pictures of the truck and the foam.  You can also see the seam in the background

 

After removing the truck I gently removed the foam remains from the wheels and they came off easily.  There was no apparent damage to the rubber wheels

 

The truck really left some indentation in the foam and it is not a heavy truck.

 

As with Jerry's post above some sort of chemical reaction with the rubber wheels plus foam softness caused the issue.

 

As a remedy I will fill the holes with putty of some sort and remove and putty the section of the track ties that have sunk.

Jerry, thanks again for your post.

 

At least I know I am not crazy seeing things!!!!!!!!!!

 

George

 

By the way the truck that was sinking was a Lionel truck part of a flatbed car.

 

Very interesting. If the indentation was solely because of weight then I would think everything on the foam would be sinking. 

 

So it appears that the latex paint does not effectively form a barrier to stop a chemical reaction between the tires and the foam. I have never experienced that problem but I make my roads etc. out of Foamcore covered with Durham's Water putty--the Foamcore having been glued over the pink foam base.

 

That IS interesting.  And a little surprising.  I just checked the cars on my layout that are directly on painted rigid foam.  A few were a little stuck to the surface, but not sunk in.

 

For patching the holes, I would use Woodland Scenics Foam Putty.  Apply with a putty knife.  Let it dry overnight and then sand.  You can also use it to make that seam disappear.  Just cut a small V in the seam first and fill it with the putty.

It is not from the weight. It is from the chemical vapors that leach from the vinyl (or whatever they are made of) tires. I have seen this happen many times over the years, and as I said before, it has happened to hard plastic. I have a clear display case that my son placed a car on top of. It now sports four sets of tread marks dissolved into the plastic.

Well that's not as bad as I thought. Actually not even near as close to "bad" as I thought.

 The curve of the track, camera angle, and my computer reverting to an old aspect ratio,(reset last night) contributed to that area looking like a "giant" sink hole.

 But it looks like it is "the tackle box effect", and those tires are the issue.

  I wonder if a better solution could be found on any die-cast/diorama specific modeling sites?

 

I'd prime(thick) and paint the holes and around them reset the wheels into the holes, and call a tow truck. (some one mentioned that didn't they?) If you can lift the front with the wrecker, fill those front holes 1/2 way with water effect.

 Maybe the business owner could be having a visit from the rep for Al's Paving too.

 

You could drop small grey blocks in/ or thin ones over it for small concrete pads too.

 

 

I have several old Japanese Godiakin toys from the 70s  I keep in the original packaging which is styrofoam and I've noticed that some of the rubber parts in these mostly die cast toys react to the foam and eat into it. My solution has been to place card stock between the rubber and the foam tray.

Not a chemist but manufacturing engineer.

In my experience when people painted wooden shelves with latex and then placed objects on them, they would occasionally "sink".
What was happening was a plastizer migration happening due to the pressure of the object. The paint was actually flowing very slowly.
Black rubber toy tires and early black rubber track ties have a tendency to continue to out gas for years untill the eventually "dry out" and crack.

It is possible that you have a combination of small pressure points, plastizer action in the paint with out gassing causing a thermal or chemical reaction just warm enough to melt the foam.
Just an opinion. Could be little leds or gnomes jumping on top of the truck.

 Change the card stock every 2-3 years. I can tell you from dealing with comics & collectibles the chemicals are soaking into it. Once they make it through, or saturate well reactions begin against the card stock. If you can find open pore on one side, and gloss on the other use that(acid free too.) Put the tires on the matte side so it can absorb into the paper better.

 

I had a few die-cast cars come with flat tires from being screwed on so tight.

Adding a spring or washers to raise them on stands would work well Id think.

 

vallieone,

What kind of track was it that was sinking into the foam, did it have metal cross ties like Lionel, or a plastic based roadbed like MTH or Fastrack? The truck sinking was definitely a chemical thing, but I'm not sure about the track. Could be that you could just add a piece of poster board between the foam and the track that could be hidden by ballasting (after painting it an appropriate color using water-based latex paint color matched to the ballast). That would make it like foam core, but with a minimum thickness difference.

 

Bill in FtL

I think most "rubber" model vehicle tires are made of some form of PVC - polyvinyl chloride. The pink foam is extruded styrene. could it be that the PVC tires is reacting with the styrene? Possible the reason the track is sinking is that the track ties are painted with a lacquer-based paint?

Did I miss something? I have yet to see a photo of where or how bad the track is sinking into the foam.

I didn't say that it was. Clearly everything on the foam is not sinking as evidenced by his photos. My second paragraph explains my view that the latex paint did not create a barrier to stop the chemical reaction.

 

 

Hmmm, did a "B" fly up your Dennis?

 

There is still nothing showing that the track has sunk into the foam. In fact, it appears that the ties are above the foam.

Jim, you have misunderstood my post. Again, I have never been in disagreement with you. You'll get no argument from me. It was the original poster who said his track was sinking in his very first post and then again in the post that accompanied this photo:

 

"I am attaching a picture of the section where it is sinking, it is the outer section of the track tie which you can't see here..." 

 

We  have not seen the track sinking and even if is, that is not related to the chemical reaction between the tires and the foam.  

 Never used it? I don't know if its a sealer, "but sounds" like it may be firm,  impermeable enough barrier that its acting like a primer.

 

Are there any holes?  A few strategic razor slices may release some trapped gasses.

Are both sides painted? Does the paint feel soft?

 

Try again in a new spot.

  If it continues, I think all you can do is accept it and rebuild.

And if its stopped, work around it, or rebuild it. A red/brown primer for a "dirt pad", over that paint, might provide a "sheet" of protection. 

 

  IMO, unless that Beep is pulling cast cars; you have a real issue, if there is sunken foam there under track too. If it has just "parted the paint", that's the paint on the foam's fault.

  Prime/test on some scrap, then weight, & wait!?

Adriatic, I have sealed foam with Latex paint and then used ACC to bond something to it. On raw foam, ACC will eat right through it. So, in my experience, latex paint does act as a barrier. I suspect you may be right about there being a break in the paint surface. Also, Ffffreddd (in his post above your previous post) presents another logical explanation to explain what could be happening. 

Not just latex. A primer is a little different than a regular paint.

Note flat paints are not primer either. Many think that's the same, but its not. Flat paint is a topcoat.

On my layout, I have always used an earth colored flat brown latex paint for a base coat over my substrate, be it foam, Homasote, ceiling tile or plywood. Nowadays, many paints come with primer already added.  

You cant "add primer" in that sense.

here's the relevant definition by Oxford dictionary

 

I would call it a topcoat without need of a primer. In that application it is more about adhesion, and low soak, meaning less coats on a job.

A primer is a "introduction" "a base". Sandable fillers, sealers, or barrier coat, choice are about doing it right for the job.

 Those same low soak, high adhesion chemicals might be an issue on foam.

A neutral primer choice should not react, if chosen correctly. Once dry it should form a barrier that would allow a carefully applied top coat, or even other primers. After a couple careful selections, you should be able to eventually topcoat with more paint types, without a reaction.   

 I.e For a "Get er done" low buck room painting. I might choose it.

But a "Real rooms" paint is usually 2 coats of primer, 2-3 top coats, with sanding between each coat, and oil base or stain on the trims.

 

   

I have not seen any evidence of the track sinking into the foam, but I have seen evidence on my own layout of certain rubber tires sinking or chemically reacting to the Pink Foam painted or not.

As to the track I place cork under the gargraves that is placed on areas of pink foam supporting the track. No issues with sinking at all.