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Old Oct 31, 2012, 04:49 PM
GeoffH is offline
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Mdf plug fiish


Hello I am wondering what would be the best option to finish my MDF plug. I soaked it with resin then a few coats of resin with 423. I am going to use wax/pva. Would there be any advantage or risk of mold realse problems with painting it with krylon or rustolem vs leaving the surface expoxy and graphite? I am assuming that painting and polishing would give a better surface vs resin and graphite sanded as good as possible. I am woried about the paint sticking to the mold.

If I finish it with resin and graphite does the entire surface need to have a uniform colour finish? I have a few spots such as edges and hatch lips where there is no graphite as the plug has been sanded down to the original resin layer. Cannot feel an edge but will there be release issues on the resin vs resin graphite surface?

Thanks
Geoff
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Old Oct 31, 2012, 06:47 PM
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First off you can always test on samples to see how things will release. This is the most reliable way to determine how everything will work.

I would forgo the paint if I was going to use PVA.
Old Oct 31, 2012, 06:52 PM
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Thank you. I tried sanding a good finish on the graphite mix and it went well. The only issues are some pin holes from air bubbles. I was thinking of primer and paint to cover these. I think will just stick with resin. Will sand everything smooth then mix some resin, 423 and filler to fix any defects or bare spots.
Old Nov 01, 2012, 02:28 AM
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Geoff,

Something that works well it to heat the resin with a flame torch or a heat gun directly after applying it, this removes the bubbles on the surface, just don't hold the heat in one place long.
Hold just long enough to pop the bubbles.

If you are going to use a filler make sure its just enough to fill and not affect the resin strength. Don't use Cabosil to thicken the resin as this will make it very difficult to sand.

If you want to paint it the best is to do it when the resin is green.
You can do the touch test which will show a finger print but is not tacky to the touch, spray over this, this will give you the best bond to the resin and should (never tried) prevent the paint from coming off.
Old Nov 01, 2012, 07:37 PM
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With many layers of paint I have found that some of the paint always comes off and sticks in the mould, even with pva. This is no big deal though unless you want to use your plug again. Because you used pva the paint should come out of the mould pretty easily and then you will have a nice mould to use.
Old Nov 02, 2012, 07:24 AM
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Josh,

I have use 2k paint which is very durable and polishes beautifully.
I have only once had the paint stick but even the mdf came with, it stuck to the mdf like superglue.
I do prefer Corian to making plugs with MDF especially because it is quick and easy.
repeated use of the molds are achievable but you must take care of the molds.

I'm sure if you ask around someone could help you with your sketches and your molds.
The trick is to ask and maybe someone would do it.

Best of luck
Orrin
Old Nov 02, 2012, 08:02 PM
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I used Krylon on my last plug and it stuck something fierce. With great effort I was able to get the plug out (probably took about 200lbs of force ), but quite a bit of paint stayed in the mold and it took a ton of work to get it all out. On my next mold I'll probably just forgo the paint. Painting when the resin was still tacky isn't something I considered, but I can see that helping.
Old Nov 02, 2012, 10:18 PM
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I personally have never had problems with the paint being pulled off.
Old Nov 23, 2012, 10:34 PM
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I'm wondering if acrylic lacquer would be any better than rattle can enamel paints for plugs.
I know that 2k is superior, but it's expensive and I do worry about the safety aspect of using it, even though I scored a supplied air helmet recently.

Jim.
Old Nov 24, 2012, 02:38 AM
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I think if you use pva your ok jim, but other wise it reacts through the wax, I think....
Old Nov 24, 2012, 03:15 AM
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I'm planning on using PVA for sure! I'm tempted to give it a go with the acrylic.
Old Nov 24, 2012, 05:04 AM
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Quote:
Originally Posted by Jimbello View Post
I'm planning on using PVA for sure! I'm tempted to give it a go with the acrylic.
Stick with the 2k Jim. You will get a better result with a higher rate success.


Tim
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Old Nov 24, 2012, 02:11 PM
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Quote:
Originally Posted by timbuck View Post
Stick with the 2k Jim. You will get a better result with a higher rate success.


Tim
+1
also i never use pva,
much better finish without it.

Flo
Old Nov 24, 2012, 03:53 PM
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Originally Posted by timbuck View Post
Stick with the 2k Jim. You will get a better result with a higher rate success.


Tim
I think that is wise advice Tim. Especially given the small draft angle the wing fillets on my Wompoo fuselage will present. I will post a picture of them on my build log for interest sake sometime later. They will be a marvel if they pull ok even with the very best of paint and release system!
Living on the edge a bit with this one.
Thanks.

Jim.
Old Nov 24, 2012, 08:04 PM
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If your not living on the edge your taking up to much space...

One of the best "NO FEAR" brand sayings..
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