I cut a hole in the wall... now what?

[TrainNut]

Yep. I should'a done that or one of the others. Being the lazy soul that I am, I chose to go with the foam idea. I thought it'd be quick and easy. However, Murphy lives in my house and the results were FAR from pleasing. I lined each hole with wadded newspaper, sprayed the foam inside and sat back and waited. After 1 hour, it was still squishy. After two hours, the center had begun to dissolve itself. After four hours of waiting, I started to cut around the edges with a hacksaw blade only to find the entire center had dissolved into one big sticky gelatinous mess. EPIC FAIL. I followed the directions on the can but obviously, there was something important I missed. Of course, I did both holes at the same time so I've got a big sticky mess X2. I'm hoping that if I give it some more time, it will eventually dry and I can salvage what's left.

[Gary S]

Oh man, I'm sorry I suggested that! :oops:

I wonder what happened? I haven't ever seen the foam do that... It always worked on filling the pipe holes. Could this be a bad can of foam? I mean, it can't be much simpler than "point and shoot." What could go wrong?

What does the can say about drying time? I am quite perplexed and embarrassed on this one. Sorrrrrrrrrrrry.... :oops:

Still, it should have worked!

[TrainNut]

It's no fault of yours Gary and for anybody else, it probably would have worked great. This is the way everything I do turns out. I'm not sure what happened. It was really strange... like I said, after a couple hours, it's like it started to digest itself from the inside out. I thought the drying time was 1 hour... I threw the can away and it's in the bottom of the dumpster now and I'm not going to go dumpster diving to verify that. I just checked what's left of the foam and 7 hours later, it seems to have finally cured so I'll see what I can do now!

[nachoman]

Some foam dries flexible, others dry rigid. If you got the flexible stuff - bad news. If the rigid stuff is applied thick, it may be overnight before cured all the way through.

[TrainNut]

I bought the stuff you guys referred to earlier... Good Stuff or Great Stuff... gap and crack filler. I guess I should have looked for the can that said, "N scale tunnel filler."

[Steamtrains]

I ran into one of those (N-Scale Gap-Filler Foam) cans sometime ago, but didn't see any need to buy it since I do HO....

Seriously...I used some of that foam to seal around AC penetrations on the outside walls of the house and it started to expand and harden almost instantly, and was fully cured a couple of hours later. Guess it's wait-and-see.....

[Gary S]

TrainNut, I was talking about the stuff that Gus is talking about!

Geez, I didn't know there are two kinds... flexible and rigid. The stuff we used cured rigid and the hacksaw cut it cleanly for a nice finish. Darn it, I'm still embarassed and perplexed.

[TrainNut]

Nah, don't worry about it Gary. I've been shaping it for a little bit now and it looks like things aren't as bad as I'd thought. It still left some big holes where it tried to digest itself but I think I can fill that with several layers of WJC and call it good.
It was a good idea and despite the complications I think it will turn out okay.

I think, when it came down to it, I guess I just didn't wait long enough for it to completely cure.

[Gary S]

I'm glad that it is working out. I was imagining you having to spend hours cleaning all that mess out of the wall and using some other method to close it up.

I've never seen the foam do what it did in the photos. Like you said, it looks like it is dissolving itself in the middle. That is soooo weird!

[MasonJar]

If you have some scraps of drywall, you can cut some patches. Cut the pieces bigger than the hole by about 2", then cut from one side only the exact size needed. Peel the paper and gypsum away leaving the paper on the other side to act as the "tape" for patching.

   

Works well. I have patched holes up to about 8 inches in diameter like this. If you don't have any scraps, your local big box hardware store likely has some damaged or broken sheets they'll give you a chunk from.

Andrew

[Russ Bellinis]

Train nut, is there a date stamped on the can? Most of the spray foam is polyurethane, and I think it has a "life expectancy" where it is still good. If it gets too old, it may have problems. It will probably eventually harden, but it should have a chemical reaction and harden within minutes of spraying. If the store sold you an old can that is beyond the expiration date, you might complain to them and at least get a refund or a replacement can of fresh stuff.

[TrainNut]

Andrew, thanks for the tip. I'll definitely file that for future use the next time I've got some holes to patch. Come to think of it, I've got one out in the garage that could benefeit from this very tip!

Russ, Come to think of it, the can did have a pretty healthy coat of dust on it but I grabbed it from the front of the shelf at Lowes so I wouldn't think it would have been out of date. I'd check the expiration on the can but like I said earlier, the cans now in the dumpster under several layers of yuck and I'm not worried about it enough to go digging for it.

[Russ Bellinis]

Stores generally rotate old stock to the front of the shelf. and put the new stock in back. On something with an expiration date, I look at the date before buying to make sure I get something fresh enough to not have any problems. On the other hand, when buying hobby products like kits or details, it sometimes pays to look for the old stock since the price may be lower on an item that has been on the shelf a while, especially if the product has had a recent price increase.

[Gary S]

TN, so how goes the holes?

[TrainNut]

It's going good. I filled in all the foam holes with WJC and let it dry for a bit. Since the trackwork inside will be temporary, I've gone with Kato Unitrack. Once I get the rest of the layout far enough along, I'll pull up the Unitrack and continue it straight through on both sides to pop out in the living room. In the meantime, I've been working on laying the rest of the cork and finishing off the trackwork enough to get both loops of the mainline continuous so I can finally run some trains. I still need to trim the cork at the edge of the wall so that the Unitrack will match up and sit flat for the transition. I was hoping to leave the Unitrack/flex joint take-apart-able but the Unitrack rails are slightly smaller than the flex track I buy and so I will end up soldering those instead.

Left side, laying cork and getting ready to connect to the Unitrack.


Same view, a little closer. I need to find another building facade to disguise the giant opening a little better.


Right side, still have not connected the flex to the Unitrack but getting closer.


And an in your face shot of the opening... I still need to paint the inside black too.