laminate surface finishing

[giorkos]

hi All,

Im new to the forum and by no means an engineer !!
i am a hobbyist getting into carbon fiber lamination.

I have been collecting information on lamination techniques and vacuum bagging, but one thing that i yet to find answers to is what i will ask below .

lets take a simple carbon fiber laminate sheet of lets say 4 layers of carbon fiber.

i know (and have seen ) that you can obtain one side of the laminate to be very smooth (glass shiny in many cases) where the other side (the side that contacts the peel ply and breather material) mat and not shiny.

my questions are:

1. if i wanted to get a sheet of laminate that will have both its sides glass shiny (or at least shiny), what do i do then. do i just vaccum bag and get normal one side shiny and one mat and then i just spray 'paint' the mat side with resin, or a suitable 'varnish' or top coat ?

2. if i wanted to get both sides of the laminate sheet to be mat (orange peel) ...can i vacuum bag my layers of carbon 'sandwiched' in peel play and breather on both sides
like i show below:

vaccum bag
breather
peel ply
carbon layers
peel ply
breather
surface (sealing to vaccum bag)


i know that my questions are very elementary , but i could really do with the answers to this, so that i can avoid spending money just to find out something that someone is willing to tell me !

Thank you ,

George

 

[berkshire]

If you want to get both sides of your lay up shiny, then you need to do a perimeter bleed instead of a vertical bleed which is what you are doing now.

Do your lay up with a perimeter of bleed felt around the edge of your part sucking the excess resin to the sides.

You may have to use a squeegee to move some of the excess resin to the perimeter at the start of the vacuum pull.
B.E.

 

[giorkos]

Hi Berkshire,

Thanks for your reply,

I will have to experiment now and see what i like best...

Thanks again,

George

 

[MSSandvik]

The surface of the laminate is typically very close to that of the contacting surfaces. not wishing to sound patranising... polished aluminium or glass which is then released gives good surfaces.

To get the 'bag-face' shiny use a caul plate. this being a flat (if making flat panels) plate of reasonable stiffness to resist the vacuum pressure. glass has a tendency to break for this, but i have got away with it in the past.

You can use peel ply on mould and bag face if you so wish. this also helps evacuate air to reduce porosity. It does however leave you with a terrible surface. Two satin/matt finish ali plates would be better.

you don't show release film as a barrier between laminate and breather. Is this intentional?