what the H3ll happened here????

General Discussion
1

ok. i’m hoping there are a few good detectives out here who can help me solve this riddle.

this problems involves a pu/pe board glassed using uv curing resin. after laminating the bottom of a freshly shaped blank, i noticed that there was an area under the lap about 5 in. x 2 in. where the foam had depressed about a 1/4 in into the board(taking the cloth with it, so its not a void under the cloth). nothing had come into contact with the board other than my squeegee during the process.

then to add insult to injury, during sanding i noticed a larger spot near the leash plug that did the same thing. now i have a guess as to what caused this divit, one of the other guys in the shop installed the leash plug and i think he set off the resin too hot.

anyone care to venture a theory??

brasco

2

Sounds like shrinking foam. All PU blanks are not created equal.

3

well…either you hit it on something will the lam was curing, or you got a bad blank, as in it’s shrinking. did you notice if the foam was really, really soft? we had some bad blanks come thru back in 2006…forgot what company they were, but same thing, you would lam a board and come back and the whole rail would be collapsed. most of the time we would catch it before getting glassed by how friggen soft the foam was.

4

thank you for your input guys. i did not notice any soft spots while i was shaping obiwon, doesnt mean they werent there though.

what is the cause of “blanks gone bad” ? and what resposibility does the manufacturer or supplier have to replace the blank?

brasco

5

Usually bad foam shows itself in shaping, but not always. Normally you’ll see a ‘‘shiny’’ spot or

some other dif in cell structure in the ‘‘bad spot’’. Sometimes it’ll shrink while you’re shaping,

sometimes it takes awhile. Anything I’m suspicious of I’ll set aside for a day or two to see what

happens. The manufacturer should definitely replace the blank, all the good ones will, no questions

asked. (if the blank was a ‘‘first’’, if it’s a second or a reject, you’re on your own).

Barnfield posted a pic of an EXTREME example of shrinkage on here a few months ago. Proof that it’s

best to only buy the top-of-the-line PU. Post-Clark, there’s been a lot of bad foam out there.