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Old    Jeff Walker (surfdad)      Join Date: Sep 2004       08-24-2009, 8:08 PM Reply   
I created a fiberglass mold of the top of a board last year, and I'm finally getting around to testing a section tonight! :-)

The mold's surface is gelcoat, so I need to apply a release to it so that the cured epoxy won't stick to the surface and ruin the mold. A fresh mold needs a bazillion coats of wax to release. :-) I use Fiberglass Supplies 306 B sealer/release wax.

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Old    Jeff Walker (surfdad)      Join Date: Sep 2004       08-24-2009, 8:11 PM Reply   
I'm testing a sandwich build - so I cut out some d-cell and a rough shape of some eps. The EPS isn't shaped to fit, just close, and hopefully the vacuum will do the final shaping.

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Old    Jeff Walker (surfdad)      Join Date: Sep 2004       08-24-2009, 8:13 PM Reply   
I believe that I can apply some paint to the release agent and it will transfer off of the mold onto the finished part.

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Old    Jeff Walker (surfdad)      Join Date: Sep 2004       08-24-2009, 8:20 PM Reply   
I just want to test a section, so I am just going to bag a small part of the mold to test the rails and release. I use putty to seal the bag.

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Old    Jeff Walker (surfdad)      Join Date: Sep 2004       08-24-2009, 8:23 PM Reply   
I then stack the laminate - Zylon, D-cell, Zylon, EPS and get ready to bag it all.

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Old    Jeff Walker (surfdad)      Join Date: Sep 2004       08-24-2009, 8:24 PM Reply   
Pulling a vacuum - hopefully it's perfect when it comes out.

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Old    Jeff Walker (surfdad)      Join Date: Sep 2004       08-24-2009, 8:29 PM Reply   
Sometimes, molding can create heavy boards because there is no escape for the resin as with bagging with a breather and perf ply. However, if the resin is just enough to cover the hotcoat and lamination amounts, I believe that less resin can actually be used, thereby creating a lighter overall board.

If the finish can be applied to the mold directly and there isn't a need for final shaping of the core, the process could easily reduce skilled labor hours to produce a board.
Old    Timmy! (timmyb)      Join Date: Apr 2007       08-24-2009, 8:55 PM Reply   
The stuff you do really amazes me! Good luck on this one! Some day I will take all of these threads worth of information that you have posted and make a board of my own!
Old    Jeff Walker (surfdad)      Join Date: Sep 2004       08-25-2009, 6:52 AM Reply   
Thanks Timmy, you're too kind.

I'm going to have to pry the test piece out of the mold, I'll wait until the neighbors are awake for that :-)

Not a great picture, but the theoory of vacuum forming did, in fact, work. The soft'ish EPS readily conformed to the underlying shape of the mold without any significant shaping. Also, the D-cell made the tight radius without issue, although I did thin that out along the last few inches, before stacking in the mold.

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Old    Jeff Walker (surfdad)      Join Date: Sep 2004       08-25-2009, 8:29 AM Reply   
A little elbow grease and the proper size hammer and plastic wedge and it's out. :-)

I was able to test and prove all the assumptions. The paint on the mold surface transferred without issue. This could be substituted with a 2 pac or polyester gloss without the need for any polishing/sanding.

The various foams retained the mold shape after demolding and I believe that with a properly seasoned mold, a board would just 'pop-out' :-)

The low density EPS did vacuum form to the conturs of the mold, elimianting the need for elaborate machining or hand shaping. Although I believe that a rough shape that is slightly oversize works best.

The fabric up against the molds surface is smooth and does have the finished quality of a GREAT hotcoat. The resin/fabric matrix leaves an exact duplicate of the mold surface.

Some pictures of the result:

After demolding

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Fabric and resin matrix at surface

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Narrative of the test results

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Old    Jonathan Tollefson (jon_tollefson)      Join Date: Oct 2005       08-25-2009, 9:55 AM Reply   
Very Nice Jeff, I can't believe the paint works like that!! Cool designs could come from that!

For my Senior Project in College, we used about the same technique for a wakeboard, however we use pour foam to create the foam blank. We also used a gel coat on the tooling surface that ended up turning out like a perfect hot coat. Do you know anything about other gel coats other than tooling gel coat? They seem to work fairly well.

I also agree that this process can cut down on a lot of the time that it takes to sand a blank, lay it up, paint it, hot coat it, and everything else that goes along with hand laying up a board. Not to mention bagging material; because you could virtually have two mold halves that press together and get the same result that the vacuum would give you. Save some cash.

Thanks for Sharing, Jon T
Old    Jeff Walker (surfdad)      Join Date: Sep 2004       08-25-2009, 10:19 AM Reply   
Yeah, exactly Jon. Oh, and thanks for the compliment. I think for stock shapes with long run cycles, a builder could reduce costs considerably and manufacture without the need for highly trained labor or high cost machines. The key would be that the shape remains the same for long enough to offset the increased cost of the mold. For the most part, I think when the part comes out of the mold, it's done other than dealing with the flash along the part line. Much less labor intensive than hand making a board, plus each part will be identical. If the only change is graphics from year-to-year, the mold could see lots of use.

The paint transfer was interesting wasn't it? I'm not sure that external paint is a good choice, but a spray gloss that would protect a decal or other laminate would make quick work of graphics.

I really don't know much about gel coats. I'm limited to the tooling gel coats which are supposed to have a polyester resin that resists heat distortion, but that could be hype for all I know.
Old    Robert Garcia (ragboy)      Join Date: Aug 2007       08-25-2009, 11:18 AM Reply   
That is very cool.
Old    Brian (TXSurf) (bac)      Join Date: Feb 2008       08-25-2009, 6:09 PM Reply   
Neat Jeff!

Its about time you did something with that mold! I remember that thread now. One step closer to being able to sell boards and produce them quickly enough.
Old    BOARDS MADE IN USA (brewkettle)      Join Date: Jan 2009       08-26-2009, 5:46 AM Reply   
and will you still have to use a vent for the 1 pound eps foam??
Old    Jeff Walker (surfdad)      Join Date: Sep 2004       08-26-2009, 9:54 AM Reply   
Thanks guys.

@ TXSurf, I know I'm a slow poke! That top half of the mold has been gathering dust! :-)

@ Jim Beam, I don't think so, although it certainly wouldn't hurt. I've done some looking into the construction and the potential for a delam. As you know, 1# EPS is mostly gas either as the air between beads or C02 inside the beads.

It is not the air in the blank that is expanding. Solid polystyrene's density is like 65 lbs/cu-ft. In the expanded form in 1 lb/cu-ft density, only 1-2% of the volume is actually plastic, and about 98-99% is CO2 blowing gas and some air in the bead gaps. There is more CO2 than air, and it is far more reactive to temperature than air. Therefore by its formulation, it is each bead of EPS that is expanding. At a small temperature increase, the volume change of the blank is absorbed by the air spaces between the beads. At higher increases in temperature, the air gaps are maxed out and the blank volume overall must increase. If vented, the air now under higher pressure, because of the bead squeezing, maintains some gaps between beads and has a place to exit. This allows a volume change with the EPS without an overall change in the blank.

Boards that have D-cell laminations (like Surftech and my test) often do not experience delamination from core expansion as readily as conventional cloth laminations. This is because the high density D-cell acts as an thermal insulating barrier. Inland Surfer's wood laminate, I'm sure, does the same. Further, the delamination, if it occurs is under the skin and doesn't really effect the exterior as that skin is still laminated top and bottom. In effect, it almost doesn't matter if the core is laminated or not.

With smaller beads and thus more air between beads, you have more room for expansion. Now that doesn't mean you can bake it at 180 degrees without ill effects, but it's the selection of the EPS that makes the difference in this sort of construction and I think dictates the use of a vent or not.

Anyway...that's my story and I'm sticking to it! :-)

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