To the builders that use West Systems resin , I have a few questions .
1 , I'm presuming 105 ?
2 , Any problems using the extra slow hardener 209 . In Qld winter ?
3 , I believe it doesn't contain UV stabilisers. If I was to use white pigment in the final coats , instead of painting , how quick will it yellow ? I could use the UV stabilised resin I have for filler and finish coat . Would it matter using different brands of epoxy ?
Im thinking of changing to West so I have more work time .
Also having the extra time , using peel ply over the hand lam . I've been told it will soak up a little resin and make it flatter , so using less resin and filler ?

The slower resin will just give you more time and cure slower which is good if your not fast at laminating and gives you more time for the rails, nose and tail.

it's good for gluing in the boxes and inserts as it does not heat up as much and wont melt the styrofoam when its thick and has q-cell ect mixed with it when filling in the gaps around the boxes and inserts.

You should be using peel ply and a wadding layer if your bagging it, yes it makes it smoother and will allow you to not use so much filler.

It does yellow, you might get a season out of it before it looks really bad, i would go a black pigment then do a white primer and sand that back, filler coat does not always get all the pinholes so it should have something over it.

I think using a UV resin over the top would be worth it.

West System have pretty good doco available.

www.westsystem.com/hardener-selection-guide/

www.westsystem.com/the-105-system/epoxy-resins-hardeners/209-extra-slow-hardener/

Wasn't there another hardner that mixed in a 3:1 and that was (more) UV stable?

Q3. Non UV resin with white pigment will yellow in under 2years if exposed to sun regularly.
Peel ply will definitely flatten n reduce excess resin whether vac bagging or not. Also cuts down sanding between layup layers.

I would not use West Epoxy without UV stable paint over - even if it is just UV screening clear coat. It is not just the yellowing but actual UV degradation to worry about...

Been years since I have used 105. From memory it's quite thick, formulated for primarily glueing and bonding. Not that you can't laminate with it but in cooler temps, having a thicker resin might be a pain wetting out surf cloth.
Check the MSDS about cure times on extra/ultra slow hardeners, they are the most temperamental to reach full cure. They will generally require a decent post cure to reach acceptable physical properties unlike regular slow/fast which will reach pretty good cure/properties at ambient temps. Also be cautious having long periods when the resin/laminate is complete but not going off. The surface will crystallise without being worked and inhibit full cure.
Exposed resin of any description will suffer property degradation when exposed to UV for extended periods whether it's pigmented, UV stable (the stabilisation additives do not last forever) or otherwise. Yellowing is mainly cosmetic & the first visible sign of UV exposure issues. It signifies what follows, the reduction in physical properties, ouch.

Select to expand quote

P.C_simpson said..
The slower resin will just give you more time and cure slower which is good if your not fast at laminating and gives you more time for the rails, nose and tail.

it's good for gluing in the boxes and inserts as it does not heat up as much and wont melt the styrofoam when its thick and has q-cell ect mixed with it when filling in the gaps around the boxes and inserts.

You should be using peel ply and a wadding layer if your bagging it, yes it makes it smoother and will allow you to not use so much filler.

It does yellow, you might get a season out of it before it looks really bad, i would go a black pigment then do a white primer and sand that back, filler coat does not always get all the pinholes so it should have something over it.

I think using a UV resin over the top would be worth it.

interesting your point about 105 and heat ;
i used 105 with 206 to stick down a minor delam and melted the styro.
i mentioned it to a friend who says he had a similar experience and that only ever happened with the west he was using.
i had used 105/206 to do that before without issue, maybe in cooler months.

Select to expand quote

fjdoug said..

P.C_simpson said..
The slower resin will just give you more time and cure slower which is good if your not fast at laminating and gives you more time for the rails, nose and tail.

it's good for gluing in the boxes and inserts as it does not heat up as much and wont melt the styrofoam when its thick and has q-cell ect mixed with it when filling in the gaps around the boxes and inserts.

You should be using peel ply and a wadding layer if your bagging it, yes it makes it smoother and will allow you to not use so much filler.

It does yellow, you might get a season out of it before it looks really bad, i would go a black pigment then do a white primer and sand that back, filler coat does not always get all the pinholes so it should have something over it.

I think using a UV resin over the top would be worth it.

interesting your point about 105 and heat ;
i used 105 with 206 to stick down a minor delam and melted the styro.
i mentioned it to a friend who says he had a similar experience and that only ever happened with the west he was using.
i had used 105/206 to do that before without issue, maybe in cooler months.

Melting the polystyrene will generally be one of two reasons.

Chemical reactions. Thinners or other 'not styrene friendly' additives used in fast-ish epoxy hardeners not behaving with the polystyrene. Rule of thumb, the faster the hardener, the higher the probability of meltdown.

Heat. Polystyrene starts sh!Ting itself at 70?C. Much more temp & you end up with a petrochemical puddle gassing off. Have run tests where bulk or fast hardened epoxy can reach 120?C. Feel free to draw your own conclusions in this case.

I've had good experiences with BoteCote resin and their non-yellowing hardener. I've used it to laminate both glass and carbon on pawlonia core kiteboards. After a full year of use there's no sign of yellowing. Not too viscous even in Vic winter and cures very strong and tough. Way less odor than any other epoxy I've used.

Here's an old school 8'4" wave board from under the house. In it's time a game changer serious dtl Taranaki waves 6mm H80 kevlar sandwich board with clear expoxy resin.
Was working a real job so built after work at factory and wanting to minimize 'undercoating, spot filling, etc clear epoxy resin from NZ manufacture Resinmax which from memory was 4:1 and great to use laminating. I think CRC brought them but point is have a good look around to see what available to you. The rails were painted with a industrial container hi build paint (employer at the time) to cover carbon patches etc and under non shid an automotive 'dulon' single pack for color with waxed polyester resin Castor sugar grip.


It was well used board that got occasional thrashing on the rocks so looking a bit rough on the rail edges

If you are looking for a good laminating resin I can recommend Araldite LY3600 laminating resin. Low viscosity, very long working time (over two hours). Nicer to work with than West 105

West system and 105 lasts long enough to work on a small thing like a windsurf board . I have done sailing dinghy hulls and its still flowing fine in 23 C temps. Just make sure you are organised and have a little dry practice. One thing to watch is not putting enough resin on before covering with peel ply. Peel ply allows you to really scrape the surface hard and work surplus resin out without disturbing the underlying fabric. Its marvellous stuff and you can even put two layers on if its still a bit wet. Key though as above is not to have bits that dont make the peel ply translucent. Its really annoying peeling off to find voids here and there where there wasnt enough resin. If you work the resin and scrape you get a lovely surface all over. Get a retarder additive if you are a bit slow or practise sticking some mat on some other thing to get comfortable with how it all works.
Painting the board to stop UV really isnt going to add weight that you will notice. Use a clear International varnish if you want your Australian pine .0005 inch ala Starboard super top surface to be visible...or go to Bunnings and buy a spray can. Its great fun and your garage floor will love a coat of West system drips. Read West System literature and a ribbed metal roller over peel ply is a good tool to wet out without excess left.