Bit of advice on Air Bubbles
Discussion
I am looking to get some parts made in CF and I know that over the years there are some here that know a bit about this.
I have already selected my source, however I wanted to know when is a job acceptable. What I mean is that I have seen some pretty shabby work (not here I might add) and some really good stuff, mostly around thickness of the gel-coat and air bubbles.
Considering how costly it is to have CF stuff made in comparison with GF, and that imperfections are impossible to fix afterwards unlike GF.....
Would you accept a job with air bubbles in the gel? I believe it is quite difficult to eradicate all bubbles, so when does 'acceptable' cross the line to 'not acceptable'?
You thoughs would be very welcome!
cheers
I have already selected my source, however I wanted to know when is a job acceptable. What I mean is that I have seen some pretty shabby work (not here I might add) and some really good stuff, mostly around thickness of the gel-coat and air bubbles.
Considering how costly it is to have CF stuff made in comparison with GF, and that imperfections are impossible to fix afterwards unlike GF.....
Would you accept a job with air bubbles in the gel? I believe it is quite difficult to eradicate all bubbles, so when does 'acceptable' cross the line to 'not acceptable'?
You thoughs would be very welcome!
cheers
Airbubbles can be avoided with pre impregnated cloth, but this needs curing in a autoclave with closed molds. Very expensive and hard to get your hands on.
Other option I used is vacuumbagging, this gets rid of excessive resin which are mostly reason for bubbles to appear and presses the cloth better down in the form.
It comes all down to being patient and careful with pooring the resin in the mixture can, mixing the resin and hardener, applying the resin on the mold, rolling out the airbubbles.
Big airbubbles the size you see in a glass of soda are due to the previous mentioned, and comes down to the patience.
Bigger airbubbles are mistakes and I wouldn't accept them. It means no resin impregnated in the cloth.
Also problem areas are tight corners where you risk the deformation of the cloth when draped in place and airbubbles due to the resistance of cloth staying in place. If this happens you should have closed molds to force the cloth to follow the shape better.
So, open molds more risk of airbubbles specially in thight corners.
Just a very very quick note.
Other option I used is vacuumbagging, this gets rid of excessive resin which are mostly reason for bubbles to appear and presses the cloth better down in the form.
It comes all down to being patient and careful with pooring the resin in the mixture can, mixing the resin and hardener, applying the resin on the mold, rolling out the airbubbles.
Big airbubbles the size you see in a glass of soda are due to the previous mentioned, and comes down to the patience.
Bigger airbubbles are mistakes and I wouldn't accept them. It means no resin impregnated in the cloth.
Also problem areas are tight corners where you risk the deformation of the cloth when draped in place and airbubbles due to the resistance of cloth staying in place. If this happens you should have closed molds to force the cloth to follow the shape better.
So, open molds more risk of airbubbles specially in thight corners.
Just a very very quick note.
My very limited understanding of carbon goes like this..
A gel coat is not used because you don't want to add any more weight than necessary.
The carbon has, or is laid up, with the minimum amount of resin required to thoroughly wet the layup.
If you want a gloss finish (which defeats the prime purpose for carbon) then lacquer is applied afterwards using normal car painting methods of rubbing down between coats and buffing afterwards.
Steve.
A gel coat is not used because you don't want to add any more weight than necessary.
The carbon has, or is laid up, with the minimum amount of resin required to thoroughly wet the layup.
If you want a gloss finish (which defeats the prime purpose for carbon) then lacquer is applied afterwards using normal car painting methods of rubbing down between coats and buffing afterwards.
Steve.
Hi Steve,
with convential methods not using AUTOCLAV you will need a transparent gelcoat, otherwise you would have the structure of the mat
visible later. For avsmooth finish gelcoat is mandatory, if you do not want the painful process to apply tranparent resin later and grind it.....the lacquer serves more for a glossy finish and UV protection. but cannot remove the structure of the carbon mat.
with convential methods not using AUTOCLAV you will need a transparent gelcoat, otherwise you would have the structure of the mat
visible later. For avsmooth finish gelcoat is mandatory, if you do not want the painful process to apply tranparent resin later and grind it.....the lacquer serves more for a glossy finish and UV protection. but cannot remove the structure of the carbon mat.
Pin-hole/cavity repairs to carbon fibre or carbon kevlar are easy so long as you have some of the original resin+activator material. Prepare them with a wire drill and use a syringe to fill the voids,careful not to overfill, allow to cure and flat/polish with 1200-2000's W+D. Same as repairing a gel coat finish, no drama at all !
Just make sure you remove all traces of release agent if you are planning to lacquer afterwards, otherwise fisheye will likely occur. Good luck.
Just make sure you remove all traces of release agent if you are planning to lacquer afterwards, otherwise fisheye will likely occur. Good luck.
Since we're on topic of carbon fibre, does anyone know exactly what a pre-peg carbon fibre body would cost? I have looked up a Ward Nissan Gt-R body kit which comprise of pre-peg carbon fenders, hood, front nose, and rear valance. Those alone cost 24k USD. Furthermore, how difficult is it to repair a damage pre-peg carbon body? ie. a crack. Additionally, how does carbon break? i.e shattered like glass, bend like aluminum.
Pre-Preg and Autoklav is the most expensive process to make carbon or kevlar parts. You need to cool the prepregs at -20 degree and usually need robots to put them - then the vaccum and autoklav machine. This is mainly used in aircraft industry and Formula 1. Carbon parts shatter like glass just watch the accidents when they hit each other the debris is immediately distributed everywhere.
Gassing Station | Ultima | Top of Page | What's New | My Stuff