Question on how to wax mold

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#1

Hi Composite Experts,

I had a question about the proper method on waxing a glass mold.; for vacuum infusion. Am I supposed to wax the glass mold, and then remove the wax (the same way you wax a car).

OR,

Am I supposed to wax the glass mold and LEAVE the wax on the mold.

I am a little unsure, because I have been waxing the glass mold and then removing the wax… but it seems like my laminate is sticking to the glass, quite a bit. I was thinking of maybe leaving the wax on this time, without removing it. Any downsides to doing this?

#2

You are supposed to wax it as you would a car - apply it, let it dry up a bit and then buff it off. As with a car, don’t let it dry out for too long or you’ll break your arm trying to fully buff it out :slight_smile:

#3

This doesn’t seem to be working out very well for me. Laminate is still sticking to a nice flat glass mold. I don’t have access to PVA.

Does anyone have ideas for a good release alternative to PVA?

#4

What about aluminum foil?
Or vaseline?
Or putting some release film on top of the mold?

#5

I’m surprised it’s sticking to a glass mold, if the mold is flat and highly polished like you’d expect normal glass to be it should be one of the easiest surfaces to release off of. You definitely cannot use aluminum foil, but release film or a vacuum bagging film should give a decent release. If you go that route just make sure you apply it taut over the glass; creases will show on your finished panel.

I’d imagine that Vaseline would not work.

What type of wax are you using? There are special wax formulations designed for mold releasing, and I’m not sure if a typical car wax would work, or at least work as well.

#6

Just use a semi permenant release. Chemlease is one of the best but a little more expensive than marbocote but either one is good… Just go for a high gloss one if that is what you are after and you will not need to release after every pull as it will be good for at least 10 pulls once you have released it up fully…

#7

Wax should not give any problems at all on a glass plate. But keep in mind the instructions, for most waxes that is: apply on a clean surface, wait for it to harden up a bit, and rub it off with a clean towel. wait for 15-30 minutes, and repeat. 5 layers should be enough. After final coat wait for 24 hours, sometimes less depending on your wax. After that a recoat with one layer should be enough. Some only recoat after a few pulls, some apply 5-7 layers every time.

Wax is a good release, but it should be applied with care. It’s not as easy as PVA, but gives a better quality, and not as care free as a semi-perm, but cheaper for small production. (although when you have a semi perm, you’ll probably won’t use wax that much any more :wink: )

#8

Susho… How true… I have 2 tins of wax that hardly ever get used… I use semi permanent release for almost everything. it has to be used for Pre-pregs anyway so it is a good practice using it with every mould and keeps it simple with every part. I just use the same product for everything.

#9

Also critical is to know which wax is used.

#10

use semi perm and save your arm and shoulders from waxing and buffing. I have plenty freekote semi.perm and I can send you a sample if you pay for the shipping :slight_smile: easy to apply and lasts you for 10 or so pulls as mentioned above. never done hand lay up with it but works perfectly for infusion.

#11

…and save a lot of time too.

Like Richard (aka morepower), I use semi perm spray applied on all things.

I use Xtend one, probably not the more glossy at all, but spraying in fine layer on well prepared polish mold give some nice result and pulled without any crack sound

#12

Don’t make the same mistake I did when using a semi perm on glass. I thought just releasing it 5 times would do. I was wrong:

The epoxy ripped chunks out of the glass:

Turns out glass is porous and you need to seal it. After I sealed it, it released 20 times with only 2 coats of release.

#13

Yikes… good tip. I would not have expected that you need to seal glass!

#14

I think either you used the wrong kind of semi permanent release, or the release went bad (left the container open too long). Usually just 2-3 coats of rekote 770nc without sealer on glass is enough for e few pulls

#15

Used Chemlease which is 6 months old. Didn’t think I would need sealer. That happened. Sealed it, then used the same Chemlease and it released beautifully. I’m gonna stand by my experience and say glass needs to be sealed. This was heat soaked tempered 20mm thick glass used as staircase panels.

#16

I second that, never used sealer on glass before and used 700nc semi-perm. That must have been good fun removing those beastly glass chunks.

Regarding the question about leaving wax until it dries, etc: depends on the type of wax - some require a wet buff and others you need to leave it to dry before buffing off.

#17

Could be the epoxy used. it could be more aggressive on the release. Which chemlease you use?

#18

Used medium temp prepreg (cures at 80 for 12 hours, I cured it at 100 for 4 hours)
Sandwiched between the glass and a 1mm plate of aluminium. The aluminium released fine without sealer.
Using Chemlease 70-90,

#19

Im not familiar with the 70-90 so I googled it and found this TDS: http://www.freemansupply.com/datasheets/Chemlease/Chemlease70-90.pdf
Its designed for polyester,not epoxy. If sealing helps solve the problem then thats good, however I would suggest using a release system better designed for your application such as Frekote 770NC

#20

Sorry, it’s 41-90. just double checked