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what kind of FG mold separator

Old 07-15-2007, 11:28 PM
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VMC
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Default what kind of FG mold separator

hello everyone Im makin a mold of a cowling but I never find out the mold separation wax method to leave a shinny piece

so this are my questions

do you use polyvinil alcohol film to separate them?
or are you just using wax over the plug and then the resin?

I have troubles with the pv film I hate it it screws up the glossy finish of the pieces

what method do you use?
Old 07-16-2007, 06:05 AM
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Ed Smith
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Default RE: what kind of FG mold separator

I never use PVA for the reasons you state. For a new mold I polish with mold release wax at least a dozen times. Spread the applications over a week or so. The time allows the wax to harden. After the initial waxing just one polish per use is adequate.

Ed S
Old 07-16-2007, 08:40 AM
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Default RE: what kind of FG mold separator

You can get a good finish using PVA, it really just depends on how the PVA is applied on to the waxed molds. An easy way is to use a cheap plastic spray bottle. Mix the PVA 50/50 with water and mix well, and pour into the spray bottle. VERY lightly mist the mold with the pva, it will look like small water droplets on the mold. Wait about 10 minutes and the PVA will wet out smooth. Apply a 2nd MIST coat and wait another 10 minutes. I usually add a third coat also and wait another 10 minutes.
Old 07-16-2007, 11:37 AM
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Default RE: what kind of FG mold separator

hey thanks....I think I´ll try both, I want that perfect finish, I know it needs a lot of patience and practice but it worths it
Old 07-16-2007, 12:24 PM
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Default RE: what kind of FG mold separator

Just go VERY light with the mist. Don't try to put it on like paint.
Old 07-16-2007, 02:33 PM
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Default RE: what kind of FG mold separator

I trick I learned while using PVA in an industrial coating application is to use a spray bottle to put a light mist of denatured alcohol over the PVA before it dries. This helps break the tiny bubbles you get, and reduces the tendency to orange peel.
Old 07-16-2007, 05:27 PM
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Default RE: what kind of FG mold separator

well this PVA water 50/50 mix doesnt work in a spray bottle its not liquid enough to have the spray effect when it comes out from the bottle, it stills a straight stream...but I think to achieve the little details of the plug like screws and panel lines, it only needs a lot of wax
Old 07-16-2007, 06:26 PM
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Default RE: what kind of FG mold separator

Wrong kind of bottle than, it has to be one with a fine mist setting, not stream.
Old 07-16-2007, 09:56 PM
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Default RE: what kind of FG mold separator

this one does it spreads a fine mist of water but the PVA doesnt ....it still having viscosity
maybe a 70 water 30 pva mix may work
Old 07-17-2007, 10:17 AM
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Default RE: what kind of FG mold separator

OK use pva on first part as safety precaution of sticking after layers of wax buffed good once first piece is pulled then look to see if pva is on part & not mold if on part in full sheet the wax & pull next part PVA is a safety net. why do rc guys insist on epoxy resins compared to polyesters? I was toolmaker for over 10 years in composites of all kinds. If I can help anyone pm me please or email me & I'll be glad to help not always on this board tho so email best result.
Old 07-18-2007, 11:28 AM
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Default RE: what kind of FG mold separator

Two things;

1. To Cadmn; We use Epoxy because it is more stable, stronger, and less brittle. It also is much nicer to use since it doesn't smell so bad.

2. To VMC; Try using PVA wiped into the mold with a soft rag soaked in PVA, then rung out. Wipe it into the mold, and wipe it until ther is a fine film covering all surfaces, but no runs or drips. It will leave a smooth, shiny surface with a very thin film of PVA. It's the best way I found to get a good surface quickly with no extra equipment, and it helps to protect the mold. Also, before using the mold, I use Meguires Carnuduba Paste Wax about six times before using the PVA the first time I use a mold. After that, I wax one time and PVA every use. If you are using the mold a lot, occaisionally clean it well with laquer thinner or a good wax remover and re-wax 5-6 times before using again.

Good Luck,

David Layne
Old 07-18-2007, 05:50 PM
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Kevin Matney
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Default RE: what kind of FG mold separator

Hi
What I do is this for the first time 6 coats of Johnson paste wax. Then I take a paper towel and a little water from a spray bottle and wipe it all. Then take the PVA with a real good fine brush. And brush it on and let it dry and good hr.
If it is the first pull I will put 2 coats of PVA. Then every time after take I will wax , then PVA
Old 07-20-2007, 09:41 PM
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Default RE: what kind of FG mold separator

PVA=Poly Vinyl Alcohol so why we thinning with water? thin with denatured alcohol! after first part pulls good, Just use wax, couple of good coats each part & should be fine

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