Mold release

SeanKewley · Jan 25, 2011

I’ve recently made a plug and mold for a canopy to use on my FE rigger (My first mold attempt.) I used FibreRelease on the plug and was not very happy with its release. I have since cleaned up my mold and re-polished it. I was wondering what some of you use successfully as a release agent for fiberglass molds.

Rudy Formanek · Jan 25, 2011

Most beginners at molding have had great results using Partall wax and PVA release on new molds. Production guys can use other releases that use rattlecan application, but most beginners have bad luck until the mold has been seasoned with a few pulls. I always use Partall and PVA after a stuck plug scare. The PVA part is the important part of the equation, the wax is more of a primer so the PVA won't bead up. a good forum on Composites is:

http://www.rcgroups.com/composites-fabrication-210/

FloridaScaleBoater · Jan 25, 2011

SeanKewley said:
I’ve recently made a plug and mold for a canopy to use on my FE rigger (My first mold attempt.) I used FibreRelease on the plug and was not very happy with its release. I have since cleaned up my mold and re-polished it. I was wondering what some of you use successfully as a release agent for fiberglass molds.

Hey Sean,

I have had good success with waxing the mold/plug with a GOOD mold release wax.

When ready to lay up a part, spray in PVA, it a green liquid, that is water soluble (soap & water cleanup)

I use my small detail HVLP gun and just mist it into the mold, do this a couple of times. let dry (about a 1/2 hour) then lay your part up

If you would like to try some, and are in the lower 48 I could send you some to try.

SeanKewley · Jan 25, 2011

Thanks for the help guys, and the offer to try a sample. I will order a small quantity of the Partall wax and PVA. This mold making is cool stuff and I will most likely do some more in the future. It really allows you to get creative with the appearance of your hulls/canopies.

Here is a picture of the plug on my JAE to give you an idea of what I'm aiming for. I modeled it after a F-15 canopy.

HTV Boats · Jan 25, 2011

Read the instructions on whatever wax you use. Allow it to set up before buffing and at least a half hour to cure between coats. Overnight for one won't hurt. 3-4 coats to start and in a new mold or for overkill in small part runs I'd wax every pull. I apply PVA with a small swatch of cloth like a good t-shirt and leave the mold with a wet look. Allow time to dry and if you don't like the finish just wash it out and redo.

Mic

SayMikey · Jan 26, 2011

On a new mold id wax it at least 5 times ,then 3 times till you pull enough parts to season the mold. Lots of good high tech stuff like freecote but draft angle helps more than anything. Nothing worse than a stuck part

SeanKewley · Jan 26, 2011

I made my first mold with 2 layers of 1.5oz glass and 2 layers of 6 oz glass on top of that. It seems pretty stiff. How many layers and weight glass should be used? I realize that some flex is needed in the mold to help with release.

SayMikey · Jan 26, 2011

All my molds are at least 1/4 thick,your mold should be rigid no flex and as shiny as the new part.

Tim leyde · Jan 26, 2011

Rudy Formanek said:
Most beginners at molding have had great results using Partall wax and PVA release on new molds. Production guys can use other releases that use rattlecan application, but most beginners have bad luck until the mold has been seasoned with a few pulls. I always use Partall and PVA after a stuck plug scare. The PVA part is the important part of the equation, the wax is more of a primer so the PVA won't bead up. a good forum on Composites is:

http://www.rcgroups.com/composites-fabrication-210/

I'll second that. This is what I use also. Never a problem!

SeanKewley · Feb 11, 2011

I finished the mold for my JAE 21FE cowl. I used Partall wax and PVA this time.

The first part should be cured later today. I built a couple of things into the mold. I molded the contour of the tub into the front of the cowl so it lays flat, and I also built a windshield outline into the mold to take the guess work out of masking the windshield.

Here is a picture of the layup curing in the mold. I have 4 plys of 1.5oz glass curing right now and will add another ply or two of 8oz cloth on top of that.

Terry Keeley · Feb 11, 2011

SeanKewley said:
I finished the mold for my JAE 21FE cowl. I used Partall wax and PVA this time.

The first part should be cured later today. I built a couple of things into the mold. I molded the contour of the tub into the front of the cowl so it lays flat, and I also built a windshield outline into the mold to take the guess work out of masking the windshield.

Here is a picture of the layup curing in the mold. I have 4 plys of 1.5oz glass curing right now and will add another ply or two of 8oz cloth on top of that.

Looks good!

Ray Sametz · Feb 11, 2011

SeanKewley said:
I finished the mold for my JAE 21FE cowl. I used Partall wax and PVA this time.

The first part should be cured later today. I built a couple of things into the mold. I molded the contour of the tub into the front of the cowl so it lays flat, and I also built a windshield outline into the mold to take the guess work out of masking the windshield.

Here is a picture of the layup curing in the mold. I have 4 plys of 1.5oz glass curing right now and will add another ply or two of 8oz cloth on top of that.

Nice clean work, learning the process myself. Don't waste so much cloth. I think 1-8oz is enough. B)

SeanKewley · Feb 12, 2011

Ray Sametz said:
SeanKewley said:

I finished the mold for my JAE 21FE cowl. I used Partall wax and PVA this time.

The first part should be cured later today. I built a couple of things into the mold. I molded the contour of the tub into the front of the cowl so it lays flat, and I also built a windshield outline into the mold to take the guess work out of masking the windshield.

Here is a picture of the layup curing in the mold. I have 4 plys of 1.5oz glass curing right now and will add another ply or two of 8oz cloth on top of that.

Click to expand...

Nice clean work, learning the process myself. Don't waste so much cloth. I think 1-8oz is enough. B)

Yeah. I'm not going to use 8oz cloth on future parts. It is too coarse and heavy to conform to the curves. I should stick with 1.5oz and then move to 3oz cloth.

Charles Perdue · Feb 12, 2011

Several things that help. One is to take a small amount of the resin that you have mixed for the layup, separate it from your batch and mix it with Cabosil to make a paste and brush this in the corners of the mold to form a small fillet before you lay the cloth. This helps the cloth to form to the edges with a small radius rather than a sharp edge. One other is to design your mold without large flat areas if you can help. Using a slight curve, especially compound curves or even with fancy raised ridges, adds a lot of stiffness to the part allowing you to use less layers or a lighter weight cloth for the same rigidity.

Charles

SeanKewley · Feb 12, 2011

Charles Perdue said:
Several things that help. One is to take a small amount of the resin that you have mixed for the layup, separate it from your batch and mix it with Cabosil to make a paste and brush this in the corners of the mold to form a small fillet before you lay the cloth. This helps the cloth to form to the edges with a small radius rather than a sharp edge. One other is to design your mold without large flat areas if you can help. Using a slight curve, especially compound curves or even with fancy raised ridges, adds a lot of stiffness to the part allowing you to use less layers or a lighter weight cloth for the same rigidity.

Charles

That's a good idea. Thanks Charles!

Here is part#1 trimmed and ready for primer.

FloridaScaleBoater · Feb 12, 2011

Sean;

Looks like you have done a FINE job,

How did it seperate from the mold? Did it POP right out?

Charles Perdue · Feb 12, 2011

SeanKewley said:
Charles Perdue said:

Several things that help. One is to take a small amount of the resin that you have mixed for the layup, separate it from your batch and mix it with Cabosil to make a paste and brush this in the corners of the mold to form a small fillet before you lay the cloth. This helps the cloth to form to the edges with a small radius rather than a sharp edge. One other is to design your mold without large flat areas if you can help. Using a slight curve, especially compound curves or even with fancy raised ridges, adds a lot of stiffness to the part allowing you to use less layers or a lighter weight cloth for the same rigidity.

Charles

Click to expand...

That's a good idea. Thanks Charles!

Here is part#1 trimmed and ready for primer.

Looks really good Sean, once you get a few parts pulled nicely under your belt, it really is a lot of fun. Your imagination is your limit. Welcome to the Hands-On club.

I wash the pulled part with denatured alcohol, acetone or lacquer thinner to make absolutely sure that there is no wax residue left on the part.

SeanKewley · Feb 12, 2011

Thanks for all the help guys!

It popped right out with no problems.

I did a wash down with rubbing alcohol and then did a quick wet sand with 400 paper. The primer went on perfectly. AND no pin holes. YIPEE!

Ray Sametz · Feb 12, 2011

SeanKewley said:
Thanks for all the help guys!

It popped right out with no problems.

I did a wash down with rubbing alcohol and then did a quick wet sand with 400 paper. The primer went on perfectly. AND no pin holes. YIPEE!

Sean, what was your mix for the surface coat. No pin holes that's great. B)

SeanKewley · Feb 12, 2011

Hey Ray,

I used Z-poxy finishing resin and 1.45oz cloth for the surface coat. I let that cure and then laminated with more plys of 1.45oz and then some 3oz cloth. It was a bit time consuming, but the part sure did turn out nice.

Mold release

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