West System epoxy with filler 404 swell / expand, normal?

[skippeer]

I’m re-installing aft anchor holder on the integrated bathing platform with sandwich GRP.

Used a 27 mm hole saw to make a 43 mm deep hole.
Filled with epoxy and filler 404, prior the hardening started the surface was alined with the teak.
Next day it had swelled / expanded.
Is that normal or did I do something wrong?

 

[Poignard]

You did something wrong!

The mixture gets hot and expands due to the formation of bubbles.

You should have built it up in layers.

 

[skippeer]

Thanks, next time smaller batches and maybe it is better with slow hardener 206 now when I am on the hard in Lagos, Portugal.

 

[Tranona]

That is a splendid example of an exotherm. Lucky it did not catch fire!. Solid epoxy is not an appropriate material for filling a 43mm deep hole. It should be plugged in some way first and then levelled with a fairing filler.

 

[thinwater]

Thanks, next time smaller batches and maybe it is better with slow hardener 206 now when I am on the hard in Lagos, Portugal.

This. Even in cool weather, you CAN'T use fast hardener for filling holes.

It can be helpful to add some fiber to large holes; eliminates cracking and makes it stronger. It can be chopped fiber, or just small bits of glass cloth crammed into the hole.

 

[skippeer]

Based on your experienses, how thick layer of 105/206 with filler 404 could I aim at per batch?

I have filler 402 milled glass fible blend in the boat for another task that I could have used instead of the 404.

Suspect that we are many WS users without the knowledge of how to replace balsa in GRP constructions in the right and secure way.
This thread will be a reminder for me and maybe others in the future.

#
My last WS work was performed without swell due to small batches yesterday afternoon, temperature was 44 degrees on epoxy surface and 34 on the teak a bit beside (Portugal). Was stressed to finish before shipyard staff planned to reinstall anchor holder 10 mm differently compared with original location.
White surface is the last epoxy task, the more light yellow is a month old (expected shipyard to reinstall anchor holder after my last visit 3 weeks ago).

In the future I will choose a cooler period of the day.