I used to make boards long ago , squeegeed polyester glass over stringered heavier foam.
They were heavier than now but were solid and never delaminated.
Ding resistance probably the same.
My question .....
Would squeegeed epoxy with good S glass over styrene core be a bad thing ?
As far as I can remember I used two layers of 4 oz on bottom and two of 4 oz on top. One 6 oz from mast track back and one more under feet. Extra on mast track and fin boxes.

Please stop me if this is wrong.
In my mind I have the perfect shape that I want but never sandwiched or vacuumed .

Select to expand quote

Imax1 said..
I used to make boards long ago , squeegeed polyester glass over stringered heavier foam.
They were heavier than now but were solid and never delaminated.
Ding resistance probably the same.
My question .....
Would squeegeed epoxy with good S glass over styrene core be a bad thing ?
As far as I can remember I used two layers of 4 oz on bottom and two of 4 oz on top. One 6 oz from mast track back and one more under feet. Extra on mast track and fin boxes.

Please stop me if this is wrong.
In my mind I have the perfect shape that I want but never sandwiched or vacuumed .

Sorry mate, unless you get very high density styrene (the closed cell styrofoam isn't a bad idea) and use lots more glass or even carbon, that board will dent like crazy.

To get the best from styrene you need to sandwich.
Polyurethane blanks had a harder crust than the inside foam. Polyester resin is harder than epoxy.

Nooooo,
Thanks decrepit from saving me from a stuff up.
Ok , so sandwich it is. Is there a flexible medium I can sandwich between layers of glass using layup instead of vacuuming ?
Or do I have to get with it and relearn everything I know ?

Select to expand quote

decrepit said..

Imax1 said..
I used to make boards long ago , squeegeed polyester glass over stringered heavier foam.
They were heavier than now but were solid and never delaminated.
Ding resistance probably the same.
My question .....
Would squeegeed epoxy with good S glass over styrene core be a bad thing ?
As far as I can remember I used two layers of 4 oz on bottom and two of 4 oz on top. One 6 oz from mast track back and one more under feet. Extra on mast track and fin boxes.

Please stop me if this is wrong.
In my mind I have the perfect shape that I want but never sandwiched or vacuumed .

Sorry mate, unless you get very high density styrene (the closed cell styrofoam isn't a bad idea) and use lots more glass or even carbon, that board will dent like crazy.

To get the best from styrene you need to sandwich.
Polyurethane blanks had a harder crust than the inside foam. Polyester resin is harder than epoxy.

sorry for barging in on this but what was the old foam called ,i am wanting to bring my first glass board back to life and was thinking of polyester with extra glass and not so saturated and then finish with filler and paint in stead of hot coat ,or epoxy build with some foam lamination,s around foot straps [i did this with a wave board years ago worked well, i don,t expect it to be light as the foam blank is heavy with out the glass ,i just like the old shape . i can always mount it in the pool room if it don,t work ,so epoxy or polyester?.

Select to expand quote

grich62 said..
sorry for barging in on this but what was the old foam called ,i am wanting to bring my first glass board back to life and was thinking of polyester with extra glass and not so saturated and then finish with filler and paint in stead of hot coat ,or epoxy build with some foam lamination,s around foot straps [i did this with a wave board years ago worked well, i don,t expect it to be light as the foam blank is heavy with out the glass ,i just like the old shape . i can always mount it in the pool room if it don,t work ,so epoxy or polyester?.

Old foam was polyurethane. poxy is more expensive, softer and a brownish colour. Polyester is harder, cheaper and clear.
Epoxy is stronger, and doesn't melt styrofoam. It works much better with carbon, polyester is too brittle it gives way before carbon can achieve it's extra stiffness. So if you want a clear finish on urethane, polyester is the obvious choice. If you are doing a carbon sandwich over styrene epoxy is the only way to go.

Select to expand quote

Imax1 said..
Nooooo,
Thanks decrepit from saving me from a stuff up.
Ok , so sandwich it is. Is there a flexible medium I can sandwich between layers of glass using layup instead of vacuuming ?
Or do I have to get with it and relearn everything I know ?

So herex is a softer foam sandwich material it's much more flexible than d-cell, and less brittle.

Then there is coremat, this is extremely flexible, it's not a foam, but I'm not sure it can be "laidup" , I've always vacuumed it.

One of my mates uses a jig with lots of strong rubber bands, to apply tension around the board, instead of vacuuming, this would work with herex, but I think it would leave big marks in coremat.
Coremat is also heavier as resin soaks through it.

Select to expand quote

decrepit said..

grich62 said..
sorry for barging in on this but what was the old foam called ,i am wanting to bring my first glass board back to life and was thinking of polyester with extra glass and not so saturated and then finish with filler and paint in stead of hot coat ,or epoxy build with some foam lamination,s around foot straps [i did this with a wave board years ago worked well, i don,t expect it to be light as the foam blank is heavy with out the glass ,i just like the old shape . i can always mount it in the pool room if it don,t work ,so epoxy or polyester?.

Old foam was polyurethane. poxy is more expensive, softer and a brownish colour. Polyester is harder, cheaper and clear.
Epoxy is stronger, and doesn't melt styrofoam. It works much better with carbon, polyester is too brittle it gives way before carbon can achieve it's extra stiffness. So if you want a clear finish on urethane, polyester is the obvious choice. If you are doing a carbon sandwich over styrene epoxy is the only way to go.

There are quite a few clear, UV stabilised epoxies around now that are produced specifically for surfboard manufacture.
From my experience trying to direct 'glass' polystyrene foam, the biggest ussue is delamitation. When your foot flexes the skin, the foam does not recover and tears away from the skin. Perhaps if you just use PVC sandwich foam on the deck under the standing area it might go OK. The core is quite a bit lighter, so you should be to glass it heavier to compensate.

Also, use small bead polystyrene.

Select to expand quote

decrepit said..

grich62 said..
sorry for barging in on this but what was the old foam called ,i am wanting to bring my first glass board back to life and was thinking of polyester with extra glass and not so saturated and then finish with filler and paint in stead of hot coat ,or epoxy build with some foam lamination,s around foot straps [i did this with a wave board years ago worked well, i don,t expect it to be light as the foam blank is heavy with out the glass ,i just like the old shape . i can always mount it in the pool room if it don,t work ,so epoxy or polyester?.

Old foam was polyurethane. poxy is more expensive, softer and a brownish colour. Polyester is harder, cheaper and clear.
Epoxy is stronger, and doesn't melt styrofoam. It works much better with carbon, polyester is too brittle it gives way before carbon can achieve it's extra stiffness. So if you want a clear finish on urethane, polyester is the obvious choice. If you are doing a carbon sandwich over styrene epoxy is the only way to go.

There are quite a few clear, UV stabilised epoxies around now that are produced specifically for surfboard manufacture.
From my experience trying to direct 'glass' polystyrene foam, the biggest ussue is delamitation. When your foot flexes the skin, the foam does not recover and tears away from the skin. Perhaps if you just use PVC sandwich foam on the deck under the standing area it might go OK. The core is quite a bit lighter, so you should be to glass it heavier to compensate. Add at least on extra layer of glass.

Coremat can work well in some situations, but be very careful not to over saturate it. It can soak up too much resin. It must have some in it though to make it stiff. I would only use it to stiffen the standing area.

Also, use small bead polystyrene.

Select to expand quote

decrepit said.. so herex is a softer foam sandwich material it's much more flexible than d-cell, and less brittle.

Wooops, sorry people the above is wrong!!!!!!!!!!!!!!!!!!!!

Herex is standard sandwich material similar to dinycell and corecell. they are all a bit brittle and need to be bent with care.

It's Airex that is more flexible and tougher, and possibly harder to get hold of.

Sandwich technique pretty much demands vacuum... I would hate to try sandwich a board without vacuum. Just get a small cheap vacuum pump, it pulls way more than you need so if there is a leak somewhere its not the end of the world. Get a needle valve so you can regulate the pressure to be between 0.2 to 0.3 bar or about -10 inHg.

You can also try 2mm cork on the deck, it works pretty well albeit a bit heavier.

Select to expand quote

decrepit said..


Old foam was polyurethane. poxy is more expensive, softer and a brownish colour. Polyester is harder, cheaper and clear.
Epoxy is stronger, and doesn't melt styrofoam. It works much better with carbon, polyester is too brittle it gives way before carbon can achieve it's extra stiffness. So if you want a clear finish on urethane, polyester is the obvious choice. If you are doing a carbon sandwich over styrene epoxy is the only way to go.

We developed some epoxies for the surf industry, so to say that epoxy is softer and brownish colour on polyurethane.. you must be using older style epoxies? That doesn't have a UV stabiliser?
Think of it this way - lets talk in PSI (pressure per square inch) Typical poly resin has a bond pressure of 500psi and most epoxies start at 2000psi with some getting up to 2500psi - it might look like its softer than poly, but that is just that poly is brittle and will crack (loosing bond) where epoxy will indent but keep more of a bond than poly - look at a indent on a poly board and you get the onion ring cracks with epoxy not so much.. so if doing a clear finish still go epoxy like a lot of surfboard manufacturers in the US and now theres a few changing over here. All Hayden Shapes PU boards are epoxy, same with Sculpt, Eye symmetry and a lot more are looking into it.

Select to expand quote

sanded said.. you must be using older style epoxies? That doesn't have a UV stabiliser?
Think of it this way - lets talk in PSI (pressure per square inch) Typical poly resin has a bond pressure of 500psi and most epoxies start at 2000psi with some getting up to 2500psi - it might look like its softer than poly, but that is just that poly is brittle and will crack (loosing bond) where epoxy will indent but keep more of a bond than poly - look at a indent on a poly board and you get the onion ring cracks with epoxy not so much.. so if doing a clear finish still go epoxy like a lot of surfboard manufacturers in the US and now theres a few changing over here. All Hayden Shapes PU boards are epoxy, same with Sculpt, Eye symmetry and a lot more are looking into it.

Yep, that's true.
Are you talking about polyurethane blanks being covered with fibreglass/epoxy resin? I'd assume they would dent vary easily, unless they've upped the foam density or are using more fibreglass.

Yes PU blanks with epoxy
We have done tests with epoxy and 1 layer of 4 all over on a PU blank (our "Pro" resin) and done the same layout with PU/Poly and 1 layer of 4 all over and the footwells are less in 6 months of use on the epoxy compared to the poly (same blank - Surfblanks Blue Superwhite - same test rider).
poly also had fractures from use on the bottom as well as "onion ring" fractures in the footwells
But there are still footwells (indents) in the epoxy.

There are epoxies and there are Epoxies... just like not polys are the exactly the same.. always look at their TDS's to see the differences. lots of epoxies are also playing with special tints and chemicals to get the photochromic "bright" colour change outside in the sun, great for colour! but does affect strength of the epoxy so always check the TDS

The only way of stopping indents is replacing the core with something less fragile - (something we are working on..) or increasing the skin thickness (layers of glass or other composites) but this will add weight and not as good as a stronger blank.

Thanks Sanded, very interesting!
How about wear resistance?
We have a big problem with our abrasive weed, fin leading edges don't last very long at all. I've gone to using stainless steel leading edges, but it's a hassle to do.

Select to expand quote

decrepit said..
Thanks Sanded, very interesting!
How about wear resistance?
We have a big problem with our abrasive weed, fin leading edges don't last very long at all. I've gone to using stainless steel leading edges, but it's a hassle to do.

Thanks Decrepit

Ours have an Acrylic mixed into it (think of the acrylic shop signs you see about) we did a test of just painting a finish coat on some pavers and left them outside for 2 years 24/7, out of all the resins only ours and one other still had a covering... (even though it was discoloured as all resins will discolour over time even with the uv stabilisers) all poly resins had weathered away to nothing as well most epoxies, ours and a high temp premium resin were the only ones left.

So it probably wont be the answer to your weed prob as that can be very abrasive over time, but it might slow the process down, stainless steel sounds like its working so that might be a good option

Select to expand quote

sanded said..
Ours have an Acrylic mixed into it (think of the acrylic shop signs you see about) we did a test of just painting a finish coat on some pavers and left them outside for 2 years 24/7, out of all the resins only ours and one other still had a covering... (even though it was discoloured as all resins will discolour over time even with the uv stabilisers) all poly resins had weathered away to nothing as well most epoxies, ours and a high temp premium resin were the only ones left.

So it probably wont be the answer to your weed prob as that can be very abrasive over time, but it might slow the process down, stainless steel sounds like its working so that might be a good option

That sounds really good, so next question, how much is it and where can I get it?
There is still a bit of wear behind the stainless I have to rebuild every once in a while. Better abrasive resistance would reduce the frequency.

And on the foot well problem with surfboards. I've come across a bright white high density foam, ( seems the same as 80kg/m3 d-cell) a 2-3mm sandwich of that would allow a much lighter blank.
I've no idea what it is, when sanded it has an acrylic smell and it works very easily.
It was inside a European x-ray table, transparent to x-rays with no artefacts.

Select to expand quote

decrepit said..

sanded said..
Ours have an Acrylic mixed into it (think of the acrylic shop signs you see about) we did a test of just painting a finish coat on some pavers and left them outside for 2 years 24/7, out of all the resins only ours and one other still had a covering... (even though it was discoloured as all resins will discolour over time even with the uv stabilisers) all poly resins had weathered away to nothing as well most epoxies, ours and a high temp premium resin were the only ones left.

So it probably wont be the answer to your weed prob as that can be very abrasive over time, but it might slow the process down, stainless steel sounds like its working so that might be a good option

That sounds really good, so next question, how much is it and where can I get it?
There is still a bit of wear behind the stainless I have to rebuild every once in a while. Better abrasive resistance would reduce the frequency.

And on the foot well problem with surfboards. I've come across a bright white high density foam, ( seems the same as 80kg/m3 d-cell) a 2-3mm sandwich of that would allow a much lighter blank.
I've no idea what it is, when sanded it has an acrylic smell and it works very easily.
It was inside a European x-ray table, transparent to x-rays with no artefacts.

Here you go
www.sanded.com.au/collections/surfboard-resins

interesting on the foam! we are working on a foam that uses alcohol as a blowing agent and is waterproof, but in early stages. the foam you are describing sounds like the new firewire/slater designs foam they are wrapping the boards with. Talking to their R&D guys it sounds similar.

Select to expand quote

sanded said..
Here you go
www.sanded.com.au/collections/surfboard-resins

interesting on the foam! we are working on a foam that uses alcohol as a blowing agent and is waterproof, but in early stages. the foam you are describing sounds like the new firewire/slater designs foam they are wrapping the boards with. Talking to their R&D guys it sounds similar.

Fantastic, looks like a great product, especially for conventional surfboard making.
I'm getting slow and stupid in my old age, 30mins pot life would be fine for making fins. But I'm not sure I can get a board in a vacuum bag in that time.
Can the resin be slowed down at all?
My shed can get over 30C in summer, I assume that would reduce pot life significantly?

If you like I can send you a foam sample, you may be able to figure out what it is.

Select to expand quote

decrepit said..

sanded said..
Here you go
www.sanded.com.au/collections/surfboard-resins

interesting on the foam! we are working on a foam that uses alcohol as a blowing agent and is waterproof, but in early stages. the foam you are describing sounds like the new firewire/slater designs foam they are wrapping the boards with. Talking to their R&D guys it sounds similar.

Fantastic, looks like a great product, especially for conventional surfboard making.
I'm getting slow and stupid in my old age, 30mins pot life would be fine for making fins. But I'm not sure I can get a board in a vacuum bag in that time.
Can the resin be slowed down at all?
My shed can get over 30C in summer, I assume that would reduce pot life significantly?

If you like I can send you a foam sample, you may be able to figure out what it is.

Sorry mate been away camping for the weekend with no internet (trying to get the kids off the screens!) Sounds Good decrepit would love to work out what it is.

We can slow it down to about 40 mins but with that formular thats the max, we can do an Epoxy 5-1 mix which we can slow down massively.

30c is about 25mins with the Flex.

Would love to see a sample of the foam! Cheers

In about 1991 i made a slalom board with m grade white beaded polystyrene core and sp clear epoxy and no stringer. 3 layers of 5oz eglass on deck plus 2 extra at back plus three extra patches under feet and one layer on bottom. It came in at 5kg which was ridiculously light. Deck seemed durable enough but bottom got a crease in it across the middle and next to the fin box sailing only flat water. Awesome but short lived. Two layers on the bottom would have been ok. In 93 i made a slalom board using blue dow wall mate foam and same laminate. I think it only had one layer on bottom but maybe two. I flogged that thing like crazzy, jumped it, sailed it hard downwind in swell, catapulted a few times and it survived. Used a home made tuttle box made of 9mm plywood. No stringer. that was with ciba lc192? epoxy and painted with single pack killrust house grade epoxy enamel. Looked rough but i made it in one weekend and it was light. You can do it without sandwich. It is not as good or as durable but quick cheap and good to teast a new shape. Some surboard guys put a layer of inegra between glass layers. Inegra is low density fiber and super tough but not very stiff by itself, use it as a thin core. Best lightest toughest board i ever made was with help from burt burger at sunova beach. Balsa sandwich and a very multi step process with vac bagging. Easiest is polyester and glass over pu core. Vac bagging is not hard. Worth having a go at. Lots if videos on line help. Knowing the tricks is key.

any one know what the old paint were that they used to color the cores on polyester boards and where to buy them.

Select to expand quote

grich62 said..
any one know what the old paint were that they used to color the cores on polyester boards and where to buy them.

There are a few different ways, you can get tints to add to polyester, so the colour goes on with the fibreglass, But you need to be good with a squeegee, any difference in resin thickness are immediately obvious. Kids water colours straight on the foam also works well, as long as it's completely dry before you laminate it. I've a vague recollection of using automotive spray paint, but it's possible that just went on the top of the glass. If you want to do that test it on scrap foam first.

Select to expand quote

grich62 said..
any one know what the old paint were that they used to color the cores on polyester boards and where to buy them.

just use acrylic spray cans. Nothing special

^^^
Thats what i used to use.