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Old Jun 27, 2013, 10:17 PM
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If I recall correctly when using Frekote the only drawback is the built up in the mold (this is mentioned on the product data sheet, or was long time ago). It might goes as far as messing up tolerances in very accurate molding processes. As Tom says the only way is to re-polish the mold and start a surface treatment again. The build up is usually a result of over use of the release agent. Most of the time operators are too concerned by products not releasing from the molds and "over wax" the molds. This not only can be detrimental to the mold tolerance wise, but as well may lead to "stick up" when using wax and/or PVA as the new (and often too thick) layer will soften the (good) under layers.

Wyowindworks: I thought that Frekote offered a cleaner to get rid of the built up... But then you will need to re-do the proper mold treatment starting from the surface sealing. Here is a very good guide for Frekote products: http://www.evroberts.com/images/evr_...e_brochure.pdf
Look at the end of the document for the trouble shooting tips and look at the specific product,with micro abrasive, to fight build up in molds.
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Old Jun 27, 2013, 11:55 PM
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The Frekote cleaner is used to clean/prep a mold before applying the sealer and release.
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Old Jun 28, 2013, 06:11 AM
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There's a cleaner product (CMR maybe?) to remove buildup but I can't find ANYONE who actually has it in stock. I assume few if anyone is using it.
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Old Jun 28, 2013, 06:34 AM
Father of Fr3aK, DLG Pilot
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Here's a picture of the buildup before I repolished the molds. This area is under a mylar "cover" that leaves a panel indented into the wing. Amazing how much dulling there is going on here due to the buildup.
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Old Jun 29, 2013, 02:14 AM
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I am currently looking at alternatives for the Frekote system and in at least two other systems they list a "cleaner with very fine abrasive". So it seems to be a pretty standard practice to, once in a while, clean the molds when using a liquid release agent. BTW this apply as well when using wax... especially in sharp corners and tight areas.
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Old Jul 26, 2013, 09:27 PM
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I use Johnson paste was and pva for over 30 years now
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Old Jul 27, 2013, 06:32 AM
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I've used PVA for a long time too Kevin, but with DLG wings it's hard to get the PVA off without using alot of water. We use such light glass that the water travels thru the glass weave and into the foam and is trapped there for a LONG time. I've had wings that picked up 15g (over 10%) in water weight and took almost a week to come back to their "dry" weight.

BTW after polishing again with really fine compound, the wing molds look perfect again and the last few parts came out beautifully. I'm playing with doing 4-5 parts between release application now instead of every other. I'm still very nervous and will probably keep pushing it until I have a stickup... but I want to see how far I can go.

I'm really a big fan of both release systems, Frekote and Wax / PVA but both seem to have their strengths and weaknesses.
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Old Jul 27, 2013, 12:47 PM
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Macking tape will take off PVA too and still be dry. All so try some air.
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Old Jul 27, 2013, 12:48 PM
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I have lost some molds to Frekote. So it will never be in my shop any more!!!!!!!
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Old Jul 27, 2013, 08:51 PM
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A few things to remember about semi-permanents:

1) They can expire
2) The appropriate mold sealer should be used.
3) Not all epoxy resins will release from semis
4) They don't facilitate a release from all types of release surfaces

I personally haven't used wax/pva in over 5 years and can't imagine going back. The time savings and finish quality is work it. Everybody has their favorites though for various reasons.
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Old Aug 13, 2013, 06:55 AM
Aussie F3K Pilot
Melbourne, Australia
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The other thing to do is make sure there is NO Silicon in your shed anywhere, throw it all away! You only need a few particles to get mixed into a layup or on a rag and you are history. Silicon is like a virus you can not see..
Silicon can be in:
Car wax
Syringes - if you use syringes to measure your epoxy you can get contamination.
Spray guns - often spray guns can have silicon lube in them.
Silicon lube
Silicon spray, as used on winch line.

Believe it or not I traced a failed fuz mould back to using a syringe to measure the epoxy with. Also, a friend of mine had a can of car wax he used to polish his kids bike and the next day had a wing get stuck in his mould. Every little touch on the bench or on your fingers can contaminate a layup.

Also, I have had 2 friends have issues with Freekote, one day it ok and the next day it is not.

I hope this helps.

Marcus
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Old Aug 27, 2013, 07:21 AM
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On a new mould i tried sealer and then priming wax + pva. The relase was absolutely easy. On another mould i tried only sealer, i had a decent release too but not so easy
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Old Oct 01, 2013, 01:49 PM
Inherent Tinkerer
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What kind of sealer is everyone using?

Jimmy
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Old Oct 01, 2013, 02:29 PM
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The one matched to your release system.

For PVA it's wax.

For Frekote it's FMS (usually)

I also use FMS for McLube 971.
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