High temp Tooling Sealants/ Moulds for carbon fiber

[CorbinJ PBR]

I was wondering if anyone knew of any good tooling sealants for MDF or Renshape molds and plugs that will leave a very nice finish on carbon fiber parts.

[Owen Thomas]

What do you mean by "tooling sealant"? You mean something non porous to stop air/resin from leaking through the mold?

[Kirk Feldkamp]

Coastal Enterprises (http://www.precisionboard.com/) has some great products worth considering. They make both high and low temperature urethane foam, and don't seem to make any temperature distinctions on their finishing products. You can always call them to be sure, but their FSC-88 WB HDU surface primer should do the trick.

[onemaniac]

One cheap way of doing it is wrapping the surface with Tuck tape (the red tape used in construction) and wax the surface a few times.
It gives very decent finish.
Obviously though it's not so great for a small, complex shape.

[Owen Thomas]

Well, the two products we use similar to the ones from Coastal linked by Kirk are drywall filler and wood glue. Yeah that's right, non-toxic, waterproof, high-temp, low-temp, paintable, sprayable, sandable, available-at-home-depot carpenters glue. We tested out some different methods last year for sealing/smoothing our molds and it turned out to be the cheapest option with the best results.

[Crispy]

I'm not a proper composites guy, but I believe we use a "High Performance Sealer" from Huntsman for Renshape tooling board.

[Lorenzo Pessa]

Using tape over MDF is not so smart.
With MDF you can't achieve a smooth surface so the tape fix on it badly.
That's better to paint the mold.

[CorbinJ PBR]

Thanks for the suggestions! My team is currently trying to test out a spray on aluminum coating that Boeing uses specifically for this type of application. However the test sample we sent to them has been there for a very long time already and progress has been slow. In the mean time I'm probably going to test out some these suggestions. Here's a pic of one of the molds I need to coat.
http://sphotos-b.ak.fbcdn.net/...1514_594110020_o.jpg (http://sphotos-b.ak.fbcdn.net/hphotos-ak-snc6/705397_10151360005881514_594110020_o.jpg)

[Will M]

We have used this stuff for years.
http://www.fibreglast.com/prod..._Primer_1041/Duratec (http://www.fibreglast.com/product/Duratec_Gray_Surfacing_Primer_1041/Duratec)

-William

[Moke]

If you paint the mould with a thin resin which will soak in first then spray with Duratec you will be laughing. This how we treat our MDF plugs at work.

[Will M]

@Mokr - Laughing because it makes it so easy?

I never tried it but I think it would be a very good idea to do two layers of Duratech (or what have you) in two differnt colors. That way you when you hit the first coat you know to stop sanding.
That would have saved me many hours repairing molds...

-William

[onemaniac]

Originally posted by Lorenzo Pessa:
Using tape over MDF is not so smart.
With MDF you can't achieve a smooth surface so the tape fix on it badly.
That's better to paint the mold.

Have you tried it? I have. It gave me some decent finish. (Very glossy and smooth, though I had to do a little bit of fine sanding to get rid of some of the epoxy lines from the seams of the overlaps)
I never said which is better. I too think paint coating is the 'smarter' choice.
It really does not hurt to know another way to do a job in case someone really needs it quick. (local hardware store vs composites distributor)

[Moke]

Originally posted by Will M:
@Mokr - Laughing because it makes it so easy?

I never tried it but I think it would be a very good idea to do two layers of Duratech (or what have you) in two differnt colors. That way you when you hit the first coat you know to stop sanding.
That would have saved me many hours repairing molds...

-William

Not so much because it's easy but rather it will work and give a good finish.

One of the old boat builders said that he's done that before and it worked well. Duratec do make different colours.