PVC "glue" is a powerful solvent which melts the PVC together, it's not for bonding PVC to other material.

Most of the different kinds of epoxy are just a question of flex and viscosity. Marine being quite thick so you can use it at different angles. Then laminating and finally infusion.
I actually do quite a bit of repair work with thin infusion epoxy since it wets out cloth easily on the board itself. The downside is it doesn't fill weave very well.

I also always mix by weight which is far more precise than any other method. Especially in the small batches you need for repairs.

From the Komatex site:
Laminating to other
material should present no problems. Common resin-based adhesives or mastics can be used. For best results, Komatex must be clean and free of dust and dirt. Check with the adhesive manufacturer to be sure it will work with Komatex PVC.

i hope if you use this , the adhesive you use, won't destroy the EPS.

About resins. All glues are "resins."

Polyester resin.
Epoxy resin.
Polyurethane resin.

Since our boards these days are blanked with EPS foam, use ONLY epoxy or polyurethane. Polyester will eat EPS foam in milliseconds.

Polyester is great for fiberglass work with boats and wind turbines (no foam), and it was the resin and glass used to build the old "glass" boards that used polyurethane foam as blanks.

For today's boards, stick with epoxy. EPOXY !!!

Today's epoxies are formulated to wet glass fiber and carbon fiber and kevlar fiber just fine.

--Retired Boeing Chemist

Select to expand quote

segler said..
About resins. All glues are "resins."

Polyester resin.
Epoxy resin.
Polyurethane resin.

Since our boards these days are blanked with EPS foam, use ONLY epoxy or polyurethane. Polyester will eat EPS foam in milliseconds.

Polyester is great for fiberglass work with boats and wind turbines (no foam), and it was the resin and glass used to build the old "glass" boards that used polyurethane foam as blanks.

For today's boards, stick with epoxy. EPOXY !!!

Today's epoxies are formulated to wet glass fiber and carbon fiber and kevlar fiber just fine.

--Retired Boeing Chemist

It is how they interact with the EPS , or other materials that's a concern. But then I got it figured out.
What does a Boeing chemist do ?

Select to expand quote

Imax1 said..
I use key hole surgery . It leaves all the original laminate for strength and neatness and is easy .
Rout through the laminate the size of the new bigger plug .
With a srewdriver gouge out the eps foam core 1 cm deeper and wider than the plug . Don't need to be neat .
With a bent nail or coat hanger scrape foam from under the laminate also 1 cm ish.
Fill with 80 kg expanding foam . No need for glueing or glassing in block . ( you could use expand foam in a can , Bunnings $8 ) .
Re rout hole plug size .
Glue in plug . If you want you could glass line the hole , I don't .
A couple small glass patch layers over the top .
This way it's a smaller fix area that the pad will probably cover .
Done , super dooper easy .
Same can be done with mast track and fin boxes .

Excellent tip, I reckon I'll try this method.
another question, when installing a fin box, is buttering with a q-cell epoxy mix essential given you're only connecting to polystyrene, which is the weakest element? I'm wondering, if pour foam is stronger/denser than polystyrene, could I use this? apologies for the hijack

Select to expand quote

Stretchy said..

Imax1 said..
I use key hole surgery . It leaves all the original laminate for strength and neatness and is easy .
Rout through the laminate the size of the new bigger plug .
With a srewdriver gouge out the eps foam core 1 cm deeper and wider than the plug . Don't need to be neat .
With a bent nail or coat hanger scrape foam from under the laminate also 1 cm ish.
Fill with 80 kg expanding foam . No need for glueing or glassing in block . ( you could use expand foam in a can , Bunnings $8 ) .
Re rout hole plug size .
Glue in plug . If you want you could glass line the hole , I don't .
A couple small glass patch layers over the top .
This way it's a smaller fix area that the pad will probably cover .
Done , super dooper easy .
Same can be done with mast track and fin boxes .

Excellent tip, I reckon I'll try this method.
another question, when installing a fin box, is buttering with a q-cell epoxy mix essential given you're only connecting to polystyrene, which is the weakest element? I'm wondering, if pour foam is stronger/denser than polystyrene, could I use this? apologies for the hijack

I use 8 pound pour foam, for boxes, that are on the small size, US , mini tuttle, slot, shortened US, surf boxes, the box itself gets wrapped in carbon and glass when installed into the hole. I may or not use a additive to the epoxy.
done this , a lot, removed a couple , they are secure and strong.

Hmm, deciphering 8 pound.
I get this.
decrep@PCSSD:~$ units 8lb/ft3 kg/m3
* 128.14771
If this is correct, that's much more dense than the 80kg/m>3 the board lady recommends.
The foam I have (GP330) is much lighter at 33kg/m3.
windsurfer polystyrene is typically 13 or 16kg/m>3.

Maybe Forceten's 8lb is per cubic yard not cubic foot, in that case it would be.
units 8lb/yd3 kg/m3
* 4.7462114
/ 0.21069437

Well no I don't think so, I was forgetting a cubic yard is 27 times bigger that a cubic foot. not 3 times.

It's obvious forcetens foam is going to do a better job than mine. But I think that 33kg/m>3 is open air, it will be denser if it's under compression while foaming, seal the hole and put a weight over it.

Here's what I could find about future foam's system.

Physical Properties: Measurements were determined on samples without skin, compression and flexural loading perpendicular to foam rise. Samples were produced on a high pressure machine.Density (moulded): 38 kg/m? Comprehensive Strength at 10% Compression: 145kPa AS 2498.3Closed Cells: 92% AS 2498.7 Water Absorption: 1.46 Vol.% AS 2498.8 Thermal Conductivity: 0.0225 W/m.K

I'm not sure 8ib foam is available here. But the blue closed cell styrofoam I use for inserts is about the same density and works well on my 20year old boards.

It's available from many sources.
fiberglasssupply.com/Product_Catalog/Pour_Foam/pour_foam.html


its 8lb per cubic FOOT.
We gone down this road / topic before, at that time I posted a place where you could purchase it.
yawn

My thought is that pour foam likely "keys" into the board's core very nicely. Epoxy won't fill voids like the expansion of the foam will.
The PVC foam "cassette" you encase things in is just to create more surface area to bond with the core.

It would be interesting to try a bigger install like a foil box with it. The last one I did I used thickened epoxy and carbon fabric but I'm not convinced that was totally necessary. An expanding glue/foam probably would have done a better job with significantly less weight.

Select to expand quote

Stretchy said..

Imax1 said..
I use key hole surgery . It leaves all the original laminate for strength and neatness and is easy .
Rout through the laminate the size of the new bigger plug .
With a srewdriver gouge out the eps foam core 1 cm deeper and wider than the plug . Don't need to be neat .
With a bent nail or coat hanger scrape foam from under the laminate also 1 cm ish.
Fill with 80 kg expanding foam . No need for glueing or glassing in block . ( you could use expand foam in a can , Bunnings $8 ) .
Re rout hole plug size .
Glue in plug . If you want you could glass line the hole , I don't .
A couple small glass patch layers over the top .
This way it's a smaller fix area that the pad will probably cover .
Done , super dooper easy .
Same can be done with mast track and fin boxes .

Excellent tip, I reckon I'll try this method.
another question, when installing a fin box, is buttering with a q-cell epoxy mix essential given you're only connecting to polystyrene, which is the weakest element? I'm wondering, if pour foam is stronger/denser than polystyrene, could I use this? apologies for the hijack

I'm a bit confused when you say connecting the box to styrene . The box is connecting to the much harder pour
foam .
If that's what you meant , are you asking about using the pour foam as a glue instead of resin ?
If so , resin will be much stronger because it fills the undercut voids on the sides of the box that joins to a layer on the sides which then sticks to the foam . Otherwise the undercuts will only be filled with no strength foam .
and , the pour foam will lift the box up even with weights on it .
If that's what your asking
Tip , for mast and fin boxes , ( no need to worry about the smaller plugs ). When pouring the expand foam ,( or can foam ), after its foamed and before its set , prick some holes into the outer skin of the foamed mushroom to release some pressure otherwise it may want to slightly lift the laminate up with the pressure .
By doing this it does create a less dense foam but mostly in the middle which you remove anyway .

Select to expand quote

forceten said..
It's available from many sources.>

Yes granted, but I can't find any aussie ones, and a lot of US sources don't ship here.
OK just did a dummy run, and your link above looks like they will ship here.


The only local stuff I can find is less than 40kg/m3.
So Imax, where did you get your 80kg stuff?

Select to expand quote

decrepit said..

forceten said..
It's available from many sources.>

Yes granted, but I can't find any aussie ones, and a lot of US sources don't ship here.
OK just did a dummy run, and your link above looks like they will ship here.


The only local stuff I can find is less than 40kg/m3.
So Imax, where did you get your 80kg stuff?

Well I'm not looking again.

Select to expand quote

Grantmac said..
My thought is that pour foam likely "keys" into the board's core very nicely. Epoxy won't fill voids like the expansion of the foam will.
The PVC foam "cassette" you encase things in is just to create more surface area to bond with the core.

It would be interesting to try a bigger install like a foil box with it. The last one I did I used thickened epoxy and carbon fabric but I'm not convinced that was totally necessary. An expanding glue/foam probably would have done a better job with significantly less weight.

been doing pour foam since 2007.
the foam acts as a buffer between the epoxy, which heats when setting, and the EPS.

Select to expand quote

forceten said..

decrepit said..
OK just did a dummy run, and your link above looks like they will ship here.

Well I'm not looking again.

Well you don't have to do you?

I don't see any advantage in using carbon or glass around the insert unless it's well tied into the sandwich. That means rounding off the edge of the sandwich, so the cloth can bend around it without creating a void. Carefully sanding back the outer layer of cloth, so the tie in doesn't create too big a lump. I've done it from scratch, by routing out the sandwich core a mm or so to accommodate that overlap, before the last layer of cloth goes on. But to do afterwards, the expanding foam seems like a much easier solution.

Select to expand quote

decrepit said..

forceten said..
It's available from many sources.>

Yes granted, but I can't find any aussie ones, and a lot of US sources don't ship here.
OK just did a dummy run, and your link above looks like they will ship here.


The only local stuff I can find is less than 40kg/m3.
So Imax, where did you get your 80kg stuff?

Dalchem in Vic .
I use a 96 kg
They have various weights