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exploding liners

post #1 of 3
Thread Starter 
has anyone had any conformable foams 'explode' on them?

Here's the situ;

Shell check ok, not tight
Blew through tubes, all clear

When the foam was going in, very little - none was going through the inside. We closed off the outer tubes when we realised, a short time later still with no foam on the inner tube, the foam exploded out the outisde front toe of the liner.

The first time, yes this happened TWICE, we hadnt checked the tubes, the second, we did, and it happened again, same boot.

All we can think is that the inner tube was split inside the liner thus giving the impression of airflow when we blew but never letting foam through. But twice??

And how does the foam burst out of the toe of the boot, don't think we left it too long.

btw we used the 'brown' mix
post #2 of 3

I have not foamed a pair of Conformable liners in many years however I foam Strolz boots with foam liners on a regular basis and have a few comments and suggestions for the future if you happen to try it again.

It sounds to me like the exit tubes were blocked - or like you said - the liners were not stitched properly and had holes in them or for whatever reason the exit tubes did not allow air, or in this case, foam to flow through. However, it seems to me (if) the liners were new they should have been stitched OK? We may never know for sure.

One question...you wrote: “We closed off the outer tubes when we realised, a short time later still with no foam on the inner tube, the foam exploded out the outside front toe of the liner”.
Did you mean to write: “then” we release the (exit) tubes? Or – as you wrote – “when” we released? which tubes did you mean? Exit or entrance tubes?

FYI...I never close the exit tubes other than when one side is flowing more than the other I 'might' pinch off one side momentarily (1 or 2 seconds) to get the other one to flow better, then I release the one I pinched right away. (Note: I am sure there are several methods that fitters use when foaming, but this works for me).

So here is what I think, assuming the liners were ok. It really does sound like the exit tubes were blocked. You said there was 'very little' foam going through the tubes and liner, which makes me believe the tubes were blocked from the beginning. You, or whoever you were foaming, should have felt foam surrounding the foot immediately. The foam cannot flow into the liner – at least not very well - unless there is adequate air flow through the exit tubes and liner. That being said, once enough pressure built up from the foam it found the weakest point at the toe of the liner.

Here is one suggestion and what I do to check for adequate air flow before foaming...

After putting the footbed in the liner, and the liner in the shell, I check to make sure there is adequate air flow by blowing through the tubes – as you did – however, I block one exit tube and blow through the entrance tube and hold the one un-blocked exit tube up to my face so I can 'feel' the air coming out through the tube. Then do the same with the other exit tube. If there is air flow I am good to go, if not, I know I have blockage and need to re-adjust the tubes and check again.

I hope this helps a little, and good luck on the next one.

Don (Strolz Boot Guy)
post #3 of 3
maybe i have just been lucky, the only one i had go wrong was when i let the trainee play with the liner prior to the foaming, he managed to pull out the entry tubes then tried to push them back into the liner and didn't tell me....what a mess!!!

Don pretty much summed everything up, had you removed or wedged open the water dams at the front of the boot so they weren't crushing the exit pipes

what shell was it BTW
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