silicone bag and sheet wax

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#1

I have a mold and I want to do a silicone bag. My question is…I can do the bag directly on the mold, or I have to do a thickness like the final piece before do the silicone bag? I can use sheet wax to make the thickness. I ask this because piece thickness is about 1 layer of 200 gr carbon + 1 of 650 carbon, so less 1 mm.
It’s a little complex shape

Some pics of mold and final piece. My doubt is for the gauge port, if I do the silicone bag directly in mold, then I will be able to put in into mold, with fiber thickness?

#2

Not about your problem but… I noticed you use resin and CF to built mould… its bad idea, try always use gelcoat on your moulds, it will stick like paint and leave nice surface without voids and air bubbles etc. + good surface to polish.

ps. Is it simple to join wax sheets if mould are bigger than one sheet ?

#3

Hi fiberpro, I don’t know if it’s simple or not to joint wax sheets, I have never used them…I will buy tomorrow for the first time.

This mold is made with transparent gel coat and then with 200 gr twill and 650 twill carbon, made with resin infusion, so without voids and air bubbles. Only the small mold (see the gauge port) isn’t made with resin infusion, here I had some problems with air bubbles

#4

you’ll have to cut and splice the wax up to get it to conform to the tool, It has some give but not a ton. You can I guess to put it burnish the seams down and together with your fingers along with some heat. Possibly try and make up some simple paper patterns for the complex zones.

#5

thanks, I guess I have to do that. I’m thinking if it’s better a rigid upper mold with a silicone insert into the gauge port. If I do like this, I don’t need every time peel ply, resin mash ecc and I can do RTML. Weight isn’t the priority, so this can be the better choice. In this case I need to use wax sheet

#6

question…I can infuse over wax sheet? or the pressure is a problem?

#7

Yes. But there will be a lot of print through.

#8

thanks ASB. I presume that PVA should be used for a 100% easy release without problems (for example, resin between the union of wax sheets)

#9

Do you know, the silicon bag you can use about only 40 times with epoxy resin? After 40 times the bag will be stiffer and not extensible.
The silicon bag excellent work with polyster resin. You can use it with polyester more than 100 times.

#10

FICI superflex sheet wax works really well for this and is compatible with Smooth On’s bushable or sprayable silicone rubber bag material. That stuff drapes over countours nicely and you can use a heat gun to really make it flow well. Have had good results with them in the past.

-Adam Hennessy
Rennessy Fabrication.

#11

thanks Geko, I didn’t know it. I thought that EP is less aggressive than PE. I can do with PE without problems

#12

thanks, now I’ve stopped with this mold, next weeks I finish it and post a pic

#13

The small gaps between the wax sheets can be filled with modelling clay.