Hi, i have some flat fibre glass panels im wanting to stiffen up. I cant mould ribs on the back, i was just going to lay up another layer or 2 of csm on the back until i came across coremat. From What ive read i can use this in the middle of the layers of csm to make it even stiffer for less weight increase.
My question is can i use it on an already cured panel ie polyester resin on, coremat on, then csm, then roller it through? Or does it have to be all layed up in one go to adhere to both sides?

I would give it a good clean with acetone , then a layer of CSM , coremat , then CSM .

what about the stick on panels used to reduce vibration in doors etc

Thanks Claire
Not seen the stick on stuff, any idea what its called to look it up?

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Originally posted by austin man
what about the stick on panels used to reduce vibration in doors etc

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Ah right, doesnt really sound like what im after then, ill give the core mat a try. Ta

I used this stuff Fibreglass Polyester 3mm Coremat XI Bulker Mat 3m x 1m on eBay (end time 17-Dec-10 15:59:30 GMT) for my hard top that I'm currently working on. You'll need quite a lot of resin (it needs to be saturated), and a layer of CSM over the top but it will stick to cured GRP if the surface is well cleaned with acetone.

Clean the surface
Apply a thick film of resin
Lay on the coremat
Saturate with resin
Lay on the CSM as normal

It makes a lot of difference to the stiffness of a panel!

Ed.

Hi Andrew,

How much coremat do you need/want?

quote:

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Originally posted by Madinventions
I used this stuff Fibreglass Polyester 3mm Coremat XI Bulker Mat 3m x 1m on eBay (end time 17-Dec-10 15:59:30 GMT) for my hard top that I'm currently working on. You'll need quite a lot of resin (it needs to be saturated)/, and a layer of CSM over the top but it will stick to cured GRP if the surface is well cleaned with acetone.

Clean the surface
Apply a thick film of resin
Lay on the coremat
Saturate with resin
Lay on the CSM as normal

It makes a lot of difference to the stiffness of a panel!

Ed.

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It is good stuff, but as others have said, just be aware it soaks up resin like a sponge.... Remember also that the resulting laminate should be symmetrical about the centre line, in terms of its layup... so if you add coremat now, you will need to also add everything currently below the coremat above it... othersie it will warp considerably (shrinkage in the resin).

best to add coremat into a moulding from day one as part of the layup, virtually no shrinkage then.

in this instance as the panel its to be added to is already cured, abrade and then wipe thoroughly with acetone as mentioned before.
as for resin loading, just because it can absorb large quantities of resin, doesnt mean you have to. On racer panels i always just use a paint roller and qucikly and lightly run over both sides of the coremat (very sparingly, but even) before adding to the panel and then add a sparingly wetted out layer of CSM or wove over the top. Try not to add resin to the additional layer of glass as the core will just absorb it, just work the pre-wetted additional csm or wove with an ally roller. Trick is to get thin even coverage and use minimum amount of resin (heavy component)

if using the foam sheet (10-15mm thick) radius the edges, chamfer,so that the CSM or wove over the top drapes over it properly and doesnt leave a gap as that affects the strength a fair bit and its always the blunt edges where the panel breaks in a shunt as it becomes a stress raiser.

Do you think shrinkage will cause me a problem, the panels are approx 1m wide x 35cm, i made them of 4x450g CSM and i was just going to add one more layer till i came accross this stuff. Thought i could maybe have just added 1 layer of coremat then a layer of 300 g/sqm to make it stronger still. If i need to add 4 layers its gona be way too heavy too. am i best just sticking to the original plan of 1 layer of csm? Thanks

Probably stick to the original plan then, but it wont be anywhere near as stiff....