As per our Day 1 Seb wasn’t available (Sunday rock-climbing training) so I asked Greg to assist us and we started with planning first.
While probably even more cryptic then the one from previous day, decoded it comes like this:
- Apply the demolding spray
- Weigh all CF so we can calculate amount of resin mixture needed
- Check if anyone has any urgent needs now (restroom visit)!
- Check all tapes are ready
- Calculate resin needs
- Prepare resin mixture (wet-job timer starts here)
- Apply 1st layer – this is probably one major change to our original plan. Serge came with idea that having a first layer wet will do well as excess resin will be soaked by the second one.
- Apply 2nd layer – this one comes as a dry one
- White tape with 50% overlap
- Office 80%-90% overlap to squeeze the job even more (wet part of our job finishes)
Job started with the demolding spray application. Serge places several markers there so we won’t miss a spot.
The next in the line was the CF weighing which worked out being roughly 47g per layer.
Based on this value we decided to prepare 150g of resin mixture in a 1:3 ratio (1 part of hardener on 3 parts of resin). Then we hit quite an interesting & unexpected obstacle just before getting it mixed – I’ve been recommended to use Nitrile gloves – but how the heck do you put them on in ~30C heat-wave?
Mixing resin was easy with scales – 37g of hardener + top up to 150g with resin. Our wet-job timer started here!!
The next stage was to make sure that all CF is getting wet properly.
On to laying the first (wet) layer + Serge using squeegee to spread resin evenly on top.
Straight to the second (dry) one.
White tape! (~10 minutes in). Here you can see that we ended up with few “white” patches where tape seems not to be having enough resin. This will be visible even more later, but raising it here as it became apparent for the first time (pretty early in process). It is likely that we still had a good chance to add some resin to fix this at this stage.
… and yes, final layer with the office tape!
Done! All in roughly 15 minutes!
At this stage we found ourselves in an interesting situation – what should we do next? As we couldn’t get the actual resin I’ve been looking for we ended up with a more traditional one which sort of even doesn’t require any heat-assisted curing. It can cure on its own though several days. Another question here was when should we expect that curing process to start as being almost an hour in the “wet” job, while mixture’s viscosity was still – honey-ish.
We left an excess resin in a jar so we can oversee that actual curing process and it actually all happened in a matter of minutes … right just when team (Serge & Greg) left. Resin temperature suddenly spiked to 90C+ and I couldn’t pinch its surface anymore.
Seb then had a quite a fun testing it – and we were quite amazed that he needed to use a hammer to actually smash it.
Discussing it further with Serge we decided to test the high-temperature (70C) curing on it as well. And so we did!
Heater needed to be injected in the wider tube again and we wrapped whole contraption in a thermal insulation to reduce the heat dissipation. Strangely contact of our temperature probe with that aluminium foil seemed to confuse readings again so I decided to cutout a bit to avoid any. That also opened way how to cross-measure temperature with our IR thermometer.
Richard’s heater & Seb’s monitoring system did the job and together with a bit of manual overload we’ve been able to keep pretty stable 70C for 90 minutes.
Giving it another hour to cool down – we started removing the white-tape wrap. It was strangely satisfying experience seeing how it is coming out.
At the end I took few pictures of that texture – it looked perfect!
Well and here we are! We apparently have an awesome CF tube ready, but I don’t seem to know any way to get it from the mold! Not like it would be glued to the Al tube, but it is so tight that it is clear that stripping it away will be difficult to the point where I am already quite negative that it will work out.
Anyway, there is still a chance that our Al tube expansion wasn’t big enough as we were using different resin than intended for our final go (150C). We should also consider using even more of that de-moulding spray, probably in multiple layers (4+) – one by one when they get dry.
Finally, there is that problem with CF not being properly wet on few places. That needs to be something we need to watch after next time.
Otherwise, I think this was an amazing job for our first go! When around and having some ideas, please leave us those in comments, as always more brains comes handy.