I want to try to do a sample pressing tonight and have always used a top sheet. I will try it without the top sheet but have a few questions.
What are you guys using to prevent the glass from bonding with the top of the mold.. I have used plastic in the past but have had the resin adhear to it. I know some of you ise a mold release. What is it (brand cet)?
Do you put another coat of epoxy on top to the glass or is the epoxy pulled from the underside durring the pressing?
After the pressing, is there sanding involved and recoating with some type of varathane?
Any help would be great!
Thanks much,
rockaukum
No top sheet help
Moderators: Head Monkey, kelvin, bigKam, skidesmond, chrismp
I do this in a vacuum bag.
I just use regular 6 mil plastic sheeting from the hardware store over my last layer, and haven't had any issues with it sticking.
Yes, you do have to put epoxy on the last layer of glass. It won't take very much, as some will seep up from the last layer. I put plenty of epoxy on and then squeegee off the excess. Just make sure it is wet out.
As far as the sanding goes, you might have to, you might not have to. My first ski came out with some ripples that I tried to sand out. The second ski came out smooth as glass (in the portions that were clamped correctly-my pump died overnight). For any long term use, I would overcoat with a outdoor type varnish, as epoxy has a tendency to yellow when exposed to UV light.
Here is a detail of my layup:
Aluminum mold w/ wax release (Mequire's carnuba wax)
P-tex w/ edges
VDS
22-oz glass
Core
22-oz glass
Graphics layer (cotton fabric)
4-oz glass
6-mil plastic sheeting
Breather
Then I seal up the bag and turn the pump on.
I just use regular 6 mil plastic sheeting from the hardware store over my last layer, and haven't had any issues with it sticking.
Yes, you do have to put epoxy on the last layer of glass. It won't take very much, as some will seep up from the last layer. I put plenty of epoxy on and then squeegee off the excess. Just make sure it is wet out.
As far as the sanding goes, you might have to, you might not have to. My first ski came out with some ripples that I tried to sand out. The second ski came out smooth as glass (in the portions that were clamped correctly-my pump died overnight). For any long term use, I would overcoat with a outdoor type varnish, as epoxy has a tendency to yellow when exposed to UV light.
Here is a detail of my layup:
Aluminum mold w/ wax release (Mequire's carnuba wax)
P-tex w/ edges
VDS
22-oz glass
Core
22-oz glass
Graphics layer (cotton fabric)
4-oz glass
6-mil plastic sheeting
Breather
Then I seal up the bag and turn the pump on.
I also have been doing this with good sucsess.
Instead of 6mill plastic I've been using a screwed up printed topsheet (the printing got messed up). I just put it shiny side down.
My breather goes on top, then into the vacuum bag..
Using a topsheet that is resonably stiff I've had perfectly smooth skis from pressing.
I origionaly used some thin plastic (not sure of thickness) and ended up with an imprint from the corrigated carboard I'd been using as breather.
Instead of 6mill plastic I've been using a screwed up printed topsheet (the printing got messed up). I just put it shiny side down.
My breather goes on top, then into the vacuum bag..
Using a topsheet that is resonably stiff I've had perfectly smooth skis from pressing.
I origionaly used some thin plastic (not sure of thickness) and ended up with an imprint from the corrigated carboard I'd been using as breather.
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MartinJern
- Posts: 48
- Joined: Sat Jul 28, 2007 1:27 pm
- Location: Sweden
I was under the impression that the peel ply sold by composite/epoxy stores put a texture on the surface so it could be bonded to other parts/layers later. If you just want to prevent the breather from sticking to the composite you can use a layer of simple painters plastic which can be bought at home improvement stores. Its alot cheaper than "real" peelply.