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Overner said..

Gestalt said..

which filler are you referring to?

I don't understand the question.

You said your advice was to fill the surface of the sandwich material and to bulk out and reduce the density of the epoxy resin to fill the holes in the surface.

Which filler are you referring to that bulks out and reduces the density of the epoxy.

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Gestalt said..

Overner said..

Gestalt said..

which filler are you referring to?

I don't understand the question.

You said your advice was to fill the surface of the sandwich material and to bulk out and reduce the density of the epoxy resin to fill the holes in the surface.

Which filler are you referring to that bulks out and reduces the density of the epoxy.

Ah OK.

Well that's up to you really, depending on the properties you want. I have a preference, the one I use is a UK based filler, which is not my secret to divulge. But in the past I have used West's Micro Light, Sicomins have a 'helium filler'. I personally find glass bubbles, talc and micro spheres too heavy / tough / hard. But that is my personal experience.

e.g.: www.westsystem.com/410-microlight/

Select to expand quote

Overner said..

Gestalt said..

Overner said..

Gestalt said..

which filler are you referring to?

I don't understand the question.

You said your advice was to fill the surface of the sandwich material and to bulk out and reduce the density of the epoxy resin to fill the holes in the surface.

Which filler are you referring to that bulks out and reduces the density of the epoxy.

Ah OK.

Well that's up to you really, depending on the properties you want. I have a preference, the one I use is a UK based filler, which is not my secret to divulge. But in the past I have used West's Micro Light, Sicomins have a 'helium filler'. I personally find glass bubbles, talc and micro spheres too heavy / tough / hard. But that is my personal experience.

e.g.: www.westsystem.com/410-microlight/

Is that basically wood dust (which I've found to be a pain to sand)?

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Paducah said..

Overner said..

Gestalt said..

Overner said..

Gestalt said..

which filler are you referring to?

I don't understand the question.

You said your advice was to fill the surface of the sandwich material and to bulk out and reduce the density of the epoxy resin to fill the holes in the surface.

Which filler are you referring to that bulks out and reduces the density of the epoxy.

Ah OK.

Well that's up to you really, depending on the properties you want. I have a preference, the one I use is a UK based filler, which is not my secret to divulge. But in the past I have used West's Micro Light, Sicomins have a 'helium filler'. I personally find glass bubbles, talc and micro spheres too heavy / tough / hard. But that is my personal experience.

e.g.: www.westsystem.com/410-microlight/

Is that basically wood dust (which I've found to be a pain to sand)?

I don't think so, but I cannot honestly answer that as I do not know. But it sands very well, and can be mixed to a lower density than PVC foam.

No I have found it is a thermo plastic micro sphere.

www.google.com/search?q=what+is+410+MICROLIGHT+made+from&tbm=isch&ved=2ahUKEwiP5ovw4YfvAhUGlBoKHXo-AgMQ2-cCegQIABAA&oq=what+is+410+MICROLIGHT+made+from&gs_lcp=CgNpbWcQAzoECAAQGFDtsQFYpPIBYLn0AWgDcAB4AIABswGIAfwSkgEFMTAuMTKYAQCgAQGqAQtnd3Mtd2l6LWltZ8ABAQ&sclient=img&ei=JQY5YM-_A4aoavr8iBg&rlz=1C1GCEB_enGB824GB824#imgrc=1SFTy41jTo1EBM

Getting a little confusing here!
There are additives for epoxy. Some are for filling and some are for bonding.
Generally the fiber ones are for bonding and the sphere ones are for filling. Different companies call them different things but if you read the small print the info should be there.
If you use filling additives instead of bonding additives you will have very different results.
No yacht painters I know use epoxy and add filler additives. Its too expensive. No boat builders i know use epoxy filler because its cheaper.

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tarquin1 said..
Getting a little confusing here!
There are additives for epoxy. Some are for filling and some are for bonding.
Generally the fiber ones are for bonding and the sphere ones are for filling. Different companies call them different things but if you read the small print the info should be there.
If you use filling additives instead of bonding additives you will have very different results.
No yacht painters I know use epoxy and add filler additives. Its too expensive. No boat builders i know use epoxy filler because its cheaper.

So how do you stop all your resin moving out of your laminate and occupying the air voids in the polystyrene or pvc when under vacuum?

e.g.

This is a different subject and two different questions.
Use pre preg and bake it for the pvc and use very low psi polystyrene. I think.
I am no expert but have built a few boards with help from boat builders.
I have destroyed boards with vac bagging.
I have cracked 5mm wood making skateboards.
I am not sure vac bagging a single layer of fabric onto a polystyrene blank is that good an idea.
There are so many different variables. The higher density foam you use the less epoxy it will use in the laminate, but more expensive. Different viscosity of epoxies etc. Different properties of epoxy.
Prepreg that bakes at a lower temp or certain pressure is being worked on. Using less electricity in the build process.
To get back to the eco side big boat companies are concentrating on the efficency. Not so much the materials.
Look into what 11th hour racing are doing and some of the boat yards in the North of France.
Not relevant to what you re doing!
I think what you are doing is great. I have a huge amount of Paulownia veneer, cork, balsa etc in my cave from trying different techniques.
As you have said the most important thing with all these products is they soak up epoxy so seal them first.
Again all this depends on which country you are in and what products you have access too and how much money you want to spend.
I have said it before and I will say it again. I spent a lot of time talking to a lot of big companies all over Europe about eco building SUP boards. At the end of the day buy local is the answer.

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tarquin1 said..
Getting a little confusing here!
There are additives for epoxy. Some are for filling and some are for bonding.
Generally the fiber ones are for bonding and the sphere ones are for filling. Different companies call them different things but if you read the small print the info should be there.
If you use filling additives instead of bonding additives you will have very different results.
No yacht painters I know use epoxy and add filler additives. Its too expensive. No boat builders i know use epoxy filler because its cheaper.

yep agree and why i asked overner. i was pretty sure he was suggesting low density fairing fillers where he should be suggesting high density bonding fillers. West systems suggest microfibers for wood so i will grab some today at least for the hardware fixing.

imax had suggested the method that west systems recommend. ie. thin epoxy to the core followed with 404 or microfiber glue mix for the structural bond.

Can anyone tell me what the difference in weight would be between pre sealing a blank when hand laminating .
Ive had a problem with cheap crumbly pvc delaminating . The resin peeled off the pvc with a layer of dust stuck to it . So I'm thinking not sealing it and letting the resin soak in would have been better in this situation . It was not vac bagged but wetted out on bench .
My concerns with hand laminating is : voids between the balsa , ( or any sandwhich material ) , and board .
A pre sealed sandwich would become stiff and would not contact the board properly without vaccing .
So , would a weaker thickened resin mix that takes up the voids be better or worse for bonding than a thin layer of normal resin with less contact ?
A vac would fix all these problems .

Select to expand quote

Overner said..

Gestalt said..

Overner said..

Gestalt said..

which filler are you referring to?

I don't understand the question.

You said your advice was to fill the surface of the sandwich material and to bulk out and reduce the density of the epoxy resin to fill the holes in the surface.

Which filler are you referring to that bulks out and reduces the density of the epoxy.

Ah OK.

Well that's up to you really, depending on the properties you want. I have a preference, the one I use is a UK based filler, which is not my secret to divulge. But in the past I have used West's Micro Light, Sicomins have a 'helium filler'. I personally find glass bubbles, talc and micro spheres too heavy / tough / hard. But that is my personal experience.

e.g.: www.westsystem.com/410-microlight/

whats the big secret? no disrespect but are you remind me of Bourke?

again to go back to my previous comments. using low density fillers in the sandwich compromises the strength because low density fillers are not recommended for structural applications..

i did use low a low density filler to seal the eps and will use the same mix to patch things as needed.

Select to expand quote

Imax1 said..
Can anyone tell me what the difference in weight would be between pre sealing a blank when hand laminating .
Ive had a problem with cheap crumbly pvc delaminating . The resin peeled off the pvc with a layer of dust stuck to it . So I'm thinking not sealing it and letting the resin soak in would have been better in this situation . It was not vac bagged but wetted out on bench .
My concerns with hand laminating is : voids between the balsa , ( or any sandwhich material ) , and board .
A pre sealed sandwich would become stiff and would not contact the board properly without vaccing .
So , would a weaker thickened resin mix that takes up the voids be better or worse for bonding than a thin layer of normal resin with less contact ?
A vac would fix all these problems .

i'm doing the resin to the balsa first method. i'll only do the side that i'm bonding so the balsa will still have some flex. once bonded i'll do the top side so by that stage the balsa is already formed.

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Gestalt said..

yep agree and why i asked overner. i was pretty sure he was suggesting low density fairing fillers where he should be suggesting high density bonding fillers.

You can lead a horse to water, but you can't make it drink.

I have tried to explain to you the advantage. It's up to you to do as you please.

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Overner said..

Gestalt said..

yep agree and why i asked overner. i was pretty sure he was suggesting low density fairing fillers where he should be suggesting high density bonding fillers.

You can lead a horse to water, but you can't make it drink.

I have tried to explain to you the advantage. It's up to you to do as you please.

no disrespect, but did you stop to consider you might be the horse?

i'm not the only person in this thread suggesting not to use low density fillers for structural applications.

i posted technical papers and manufacturers sheets to add weight to the conversation. I can't find anything or anyone to back up what you are saying. it feels like hearsay.

if you can provide something or i can find something i'll buy into what you are saying.

as an example, you suggested microlight. below is a screen shot of what the manufacturers of microlight suggest. as you can see it doesn't suggest microlight for any structural purposes. actually they suggest microfibers for use with wood when you read the data sheets.


today i went to the local boat builders and asked their opinion. they said do not use low density fillers to glue the balsa. they sold me aerosil. suggested i seal the balsa with neat epoxy then use the epoxy/aerosil mix for glue. every person i have spoken to has said something similar by recommending using a bonding filler.

Neigh.....

Qcel sealed then sanded blank




Basalt stringers on.

I didn't suggest you use a low density filler to glue the balsa. I suggested you fill the micro pores as a surface preparation to prevent too much resin absorption and prevent a resin starved laminate.

But if I'm not preaching what you want to hear, no matter how loud I get it won't convert you.

it doesn't matter if you use the low density filler you suggested to fill the sandwich core or as the glue you will still produce a weaker sandwich. low density filler is not recommended for structural applications.

the recommended method is to seal the end grain balsa with neat epoxy.
that is the method recommended to me by the surfboard and boat builders i spoke with and also referenced in boat building guides i read and within the west systems manual on bonding.

here is the section from the west systems manual.

3.2 Bonding (gluing)

This section refers to two types of structural bonding. Two step bonding is the preferred method for most situations because it promotes maximum epoxy penetration into the bonding surface and prevents resin starved joints. Single step bonding is occasionally used when joints have minimal loads and excess absorption into porous surfaces is not a problem. In both cases, to achieve the ultimate bond strength, work the epoxy into the surface with a roller or brush.

Two-step bonding

1. Apply a resin/hardener mix to the surfaces to be joined (Figure 9). This is called "wetting-out" or "priming" the bonding surfaces. The epoxy is applied with a disposable brush in small or tight areas; wet-out larger areas with a foam roller or by spreading the resin/hardener mix evenly over the surface with a plastic squeegee/spreader. Proceed with step two immediately or any time before the wet-out coat becomes tack free..........

page 14. WEST SYSTEM user manual with hyperlinks 5th May 2004.indd

honestly, it's not that you are preaching what i don't want to hear. what you are preaching i have been specifically told not to do and i'm trying to be polite by backing up my statements with supporting information to convince you. should i follow your advice or the advice of the people that make the epoxy and fillers. is it possible you should rethink your approach? this feels like deja vu and i'm speaking to bourke.

To my knowledge Bouke doesn't hide behind pseudonyms other than 'Witchcraft'. I am not Bouke.

I find it amusing you find me frustrating, like you found Bouke. I'm taking that as a compliment.

Have a look at potting compounds used in aerospace honeycomb structures. It is a low density epoxy filler, no microfibre. Yet they site stronger mechanical bonds, tougher sandwiches, better vibration control, etc. If you consider foams as inconsistent honeycomb structures (because of the micro pores they are) then you can start to build a picture of what I am trying to achieve.

You could pour resin in there if you want, or thickened microfibre epoxy. It's no skin off my nose. The term sledge hammer to crack a nut comes to mind.

Have a look at Carbon Art's video on sandwiching and there you will find the secret I am not at liberty to give you. And believe me it doesn't include micro fibres or thixotropic resin. If another board builder is using it other than myself... I can't be that far wrong.

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Overner said..
e.g.

I'm confused here .
Im presuming in both these cases the resin impregnated cloth is done on the bench not the board , so how can the pic on the left be heavier ?
In hand laminating it would make sense .
Also , when hand laminating and using more resin , even though the laminate may be no stronger , it would have to bond better to the core .

I've seen a board build vid where they use a sheet of plastic with millions of tiny holes , over the lams and then on top of that have a thick sheet of something . In the vac bag it would absorb any extra resin . Talk about trying to get out every oz of unwanted resin . I would be worried about resin starvation .
Not very eco friendly .

Not very secret if he mentions it in the video.
Foaming agent for the epoxy.
I bought some last year and was playing around with it for this use. I got the idea again from Grant Newby's technique of vac bagging wood onto a blank with PU glue. The PU glue foams up and really pushes into the blank.
I thought wouldn't it be good to be able to do that with epoxy.
Never made a board but made some test pieces with various results.
Again the vac pressure is crucial. Too much seems to stop the foaming process or suck all the bubbles out.
Interesting he uses West system.

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Overner said..
To my knowledge Bouke doesn't hide behind pseudonyms other than 'Witchcraft'. I am not Bouke.

I find it amusing you find me frustrating, like you found Bouke. I'm taking that as a compliment.

Have a look at potting compounds used in aerospace honeycomb structures. It is a low density epoxy filler, no microfibre. Yet they site stronger mechanical bonds, tougher sandwiches, better vibration control, etc. If you consider foams as inconsistent honeycomb structures (because of the micro pores they are) then you can start to build a picture of what I am trying to achieve.

You could pour resin in there if you want, or thickened microfibre epoxy. It's no skin off my nose. The term sledge hammer to crack a nut comes to mind.

Have a look at Carbon Art's video on sandwiching and there you will find the secret I am not at liberty to give you. And believe me it doesn't include micro fibres or thixotropic resin. If another board builder is using it other than myself... I can't be that far wrong.

i've seen the videos a few times. very well done and great to watch.

are you recommending i use foaming epoxy without a vac bag. i'm not using a vac bag.

lets look at what carbon art use that i am not using.

heated wetout tables,
heated curing ovens,
vac bags
rocker tables.

Any reason you resist using a vac bag?

I keep coming back (in my head) to the elegance of a wood sandwich using PU glue. I use PU quite a bit for repairs and it really reinforces the core nicely.

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Grantmac said..
Any reason you resist using a vac bag?

I keep coming back (in my head) to the elegance of a wood sandwich using PU glue. I use PU quite a bit for repairs and it really reinforces the core nicely.

vac bag produces waste and adds cost both of which i'm trying to avoid. also, vacuum pumps are noisy and need to run for 6 hours. i'm building these boards in my garage in a residential area.. running a vac pump for 6 hours is something i am trying to avoid and i'm just not keen to do.

i don't believe i need to vac bag to produce a well built structurally sound board and have to say i prefer the feel of boards that aren't super stiff.

what i'm doing is bespoke. sure i'm interested in pushing the boundaries and exploring new techniques and processes. i can because this is a bespoke project but those ideas and advice need to be achievable within my current setup

Very interesting discussion. I am learning some great things. I use a old fridge compressor to do my vacuum bagging. I to could not handle the racket from my first vacuum pump. Yes there is a lot of waste bagging but as a garage hack builder I think it helps guarantee a level of success as long as you keep the pressures down. Good luck with your build.

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boardhead said..
Very interesting discussion. I am learning some great things. I use a old fridge compressor to do my vacuum bagging. I to could not handle the racket from my first vacuum pump. Yes there is a lot of waste bagging but as a garage hack builder I think it helps guarantee a level of success as long as you keep the pressures down. Good luck with your build.

a friend suggested i look into laboratory pumps as they are quieter. costly tho.

can't help but think the simpliest and easiest to get right method is a simple high density eps blank with a couple of layers of cloth and some extra reinforcing....like a surfboard. no vac bag or sandwich construction needed.

this board was an experiment to see what happens if i build something half way between surfboard construction and a fully bagged sandwich board. based around light weight eps. keen to see how it turns out and how strong it is,

the last board i built was simply 2 layers of 6oz over a 28kg/m3 blank and it has something about it i can't put my finger on when turning. could be flex. not sure really just that it is very smooth around corners.

speaking of learning great things. when at the boat yard yesterday i was commenting on how its so hot and the resin is going off super quick, the guy suggested i put the part A in the fridge to help.

4.5oz basalt biax cloth patches and inlay ready to go. 2x nose, 1x pads, 1x mast and a full inlay.




4oz basalt cloth ready to go.


biax inlay and patches laminated.


basalt cloth laminated.




i really pushed the limits of my skills with this because i decided to laminate all layers in one go to minimise the resin and get a better mechanical bond between layers. i did the biax patches and inlay first then the final layer of basalt cloth while the biax was still wet. the rebate edge for the balsa also made the rails harder to manage.

the basalt cloth is great to work with. it's soft and drapes really nicely. having never used either basalt or biax before i had no idea what to expect. the biax cloth holds a huge amount of resin which i didn;t expect so had to make up additional resin batches to keep things moving. i also found the best way to work the biax was to follow the 45 degree fibers and not try and squeegee nose to tail like normal cloth. i had to work the biax more than usual to make sure i'd pulled as much resin a possible prior to the next layer being laminated.

all up used about 750g of resin which is about 100g more than i was hoping.

I'm having the opposite problem. Over an hour until the epoxy gels even with a fast hardener. Was starting to worry that I'd messed up the ratios until I brought the whole thing inside next to the fire. Thankfully it was just a nose repair and not a full build (haven't done that yet).

I thought there were ways people have worked on to do vac bagging without any significant waste? Also the few times I've seen it done didn't seem very loud, maybe that was because they used an old fridge pump?

Lookin good Gastalt
Will u glass over the balsa , if so will it be clear to see the balsa sexiness ?
On my build I used 4.5 oz biax glass under standing area and that also used a huge amount of resin . I think it's a biax thing . Even though it's light and bendy it is thick . Probably best used in a vac .

Nice work. Yes thats a lot to do in one go by yourself.
I mix up batches if I am doing a SUP. I did a 11x30 SUP once. Thats when pumps are great and you can quickly mix another batch.
Pouring the mixed epoxy into a big roller tray will slow it down as well.
I had a few cups of resin measured out so I just had to add hardener. I have a big syringe I use for the hardener. Put the resin cup on the scale add hardener with syringe. Its quick and easy.
Lab pumps are diaphram pumps. I bought one that had a valve and gauge added. Quiet and no oil mist that you get from a normal pump. Expensive but worth it if you decide.
Still can't get basalt here!
Keep the pics coming.