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Old Apr 14, 2004, 10:40 PM
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Talon Driver's Avatar
Albuquerque, NM
Joined Apr 2002
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Which is Better for Glassing Foam WB Polycrylic or WB Polyurethane?

I have used Min Wax's Polycrylic for glassing foam. That is 3/4 oz glass. However, even after 5 coats you can still dent the polycrylic glass.

Is Water based polyurethane tougher than polycrylic?

Cheers,

Chuck
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Old Apr 15, 2004, 12:54 AM
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I have been experimenting with samples of both and I don't see that the water based polyurethane is any harder. I think the polyurethane dries faster and is easier to sand than the polycylic but it seems just as soft when I test poke it. I have tried Polyurethane glue (Elmer Probond) and it seems a lot harder. I then over coat it with the water based Polyurethane until the weave is filled. The only problem with the glue is it tends to foam if the weather is humid. On a nice dry low humidity day it is what I prefer to use to put the fiberglass down and it holds better to the foam. I have found that the less polyurethane glue used the less change of it foaming. I use just enough to wet the weave.
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Old Apr 15, 2004, 07:51 AM
OK, Who's Flying The Jet?
Talon Driver's Avatar
Albuquerque, NM
Joined Apr 2002
312 Posts
Foamless Polyurethane?

Is there such a thing a foamless (foamsafe) polyurathane glue?

Someone told me in another thread there was such a thing but I have never seen it:

http://www.rcgroups.com/forums/showt...753&highlight=

If so then it could be cut with water and applied.

Chuck
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Old Apr 15, 2004, 11:30 AM
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La Mesa, CA, US
Joined Jan 2001
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Someone else can correct me if I'm wrong, but I think you want more glass for a harder surface. For ding proofing I don't think it matters what the binding agent is when your reinforcement layer is so thin.

Brad
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Old Apr 15, 2004, 02:53 PM
OK, Who's Flying The Jet?
Talon Driver's Avatar
Albuquerque, NM
Joined Apr 2002
312 Posts
Retransmit Please

Brad,

Quote:
Originally Posted by chemsurfer
Someone else can correct me if I'm wrong, but I think you want more glass for a harder surface. For ding proofing I don't think it matters what the binding agent is when your reinforcement layer is so thin.

Brad
I didn't track this. Please reword after you read this.

The "glass" is the fiberglass. The "glass" is not the glue material impregnating the fiberglass matrix.

So, if "foamless" polyurethane exists and it is harder than polycrylic then I have found what I want. (Assuming the "foamless" polyurethane is just as easy to work with as polycrylic).
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Old Apr 15, 2004, 02:54 PM
OK, Who's Flying The Jet?
Talon Driver's Avatar
Albuquerque, NM
Joined Apr 2002
312 Posts
Retransmit Please

Brad,

Quote:
Originally Posted by chemsurfer
Someone else can correct me if I'm wrong, but I think you want more glass for a harder surface. For ding proofing I don't think it matters what the binding agent is when your reinforcement layer is so thin.

Brad
I didn't track this. Please reword after you read this.

The "glass" is the fiberglass. The "glass" is not the glue material impregnating the fiberglass matrix.

So, if "foamless" polyurethane exists and it is harder than polycrylic then I have found what I want. (Assuming the "foamless" polyurethane is just as easy to work with as polycrylic). This would make my glassed foam more dent resistant.

Cheers,

Chuck
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Old Apr 15, 2004, 03:10 PM
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chemsurfer's Avatar
La Mesa, CA, US
Joined Jan 2001
419 Posts
Sorry, I still like the way I worded it... okay, perhaps binding agent is not good wording. Use more glass as in fiberglass, as in try two layers of the .75 oz fiberglass, or maybe 1 layer of 1.4 with a .75 over that. There will be more "binding agent" (epoxy, polyurethane, or polycrylic etc...) used when more glass is used, since you need to fill the weave. But I think you may be expecting a lot of ding resistance for such a thin layer of protection.

You have to balance out your durability needs with your weight limits of course. I know there are far more experienced people on here in that area.

BTW, what are you building? That info would really help those more experienced types help you out!

Brad (B.S. in Chem, not English )
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Old Apr 15, 2004, 03:26 PM
OK, Who's Flying The Jet?
Talon Driver's Avatar
Albuquerque, NM
Joined Apr 2002
312 Posts
Is The Such A Thing As "Foamless" Polyurethane?

Brad,

Your definition of glass as originally used was correct. I just didn't conceive that you you were applying a second layer of fiberglass. Now I got it.

I do have high expectations, but not unreasonable. After 5 coats of polycrylic, on my Projeti, which is a lot, I can validly say this with 3/4 oz fiberglass is not very dent resistant on foam. Yeah going thicker by adding another layer would improve dent resistance.

But, I know if I were to use an epoxy, which is harder, but more arduous to work with, rather than polycrylic I would achieve greater resistance to denting.

Help me? At this moment I am not needing to glass anything, but will glass foam in the future. To help answer the earlier question:

Is there such a thing as foamless polyurethane glue that can be cut and used for glassing?

Since polyurethane glue is both hard and tough it would be ideal for glassing provided it didn't foam when cut with water to make it fluid enough to apply as easily as Polycrylic.

Another question:

Is there a non-foaming agent that is foam friendly and harder than polycrylic yet as easy to work with if not easier than polycrylic for glassing?

Cheers,

Chuck
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Old Apr 15, 2004, 06:03 PM
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BMatthews's Avatar
The 'Wack, BC, Canada
Joined Oct 2002
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One thing you have to realize is that fiberglass cloth of one oz and under is primarily a finishing layer rather than a strength layer. Thickening the binding layer by adding more resin or poly'whatever isn't going to change that. Using epoxy will offer a trifle more stiffness as the epoxy is harder than the poly'whatever but the real dent resistanct comes from the thickness of the glass. Unfortunetely with the extra thickness of glass comes more weight. Just adding more coats of poly'whatever won't provide any great increase in dent resistance.
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Old Apr 15, 2004, 08:57 PM
OK, Who's Flying The Jet?
Talon Driver's Avatar
Albuquerque, NM
Joined Apr 2002
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BMathews,

Copy all. Break Break.

If anyone knows if there is or is not such a thing as "foamless" Polyurethane just let me know.

Cheers,

Chuck
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Old Apr 16, 2004, 01:32 AM
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I don't think you will find foam save Polyurethane glue. The more humid it is the more it tends to foam. If you add water it really foams. I live in a desert type area and during the summer it is real dry. I can apply the glue full strength and use a flexible squeegee to spread the glue. I then drape the fiberglass onto it. It takes a little practice but is not much harder to do then any of the other processes. If it is real dry it will hardly foam at all. I apply three coats of polyurethane glue using as little glue as possible and then use the water-based polyurethane as a leveling and sanding finish coat. If the glue does foam a little it can be sanded before covering with the water based polyurethane.
The hardest surface that I have experimented with is one glue coat, followed by lots of water-based polyurethane and finished off with a smeared coat of 30-minute epoxy. The glue and the epoxy are applied with a card type squeegees.
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Old Apr 16, 2004, 07:34 AM
OK, Who's Flying The Jet?
Talon Driver's Avatar
Albuquerque, NM
Joined Apr 2002
312 Posts
Spinningreserve,

Copy there does not appear to be a "foamless" polyurethane glue.

Anyone able to answer this?:

Is there a non-foaming substance that is styrofoam friendly and harder than polycrylic or WB polyurethane yet as easy to work with if not easier than polycrylic for glassing?

Cheers,

Chuck

Cheers,

Chuck
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Last edited by Talon Driver; Apr 16, 2004 at 07:37 AM.
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Old Apr 16, 2004, 07:52 AM
OK, Who's Flying The Jet?
Talon Driver's Avatar
Albuquerque, NM
Joined Apr 2002
312 Posts
Moderator Look At This

Moderator,

Look up above this and you will see two entries to this thread that are alike. I do not know how this happened.

Could you delete one of them and this one?

Cheers,

Chuck




Quote:
Originally Posted by Talon Driver
Brad,

I didn't track this. Please reword after you read this.

The "glass" is the fiberglass. The "glass" is not the glue material impregnating the fiberglass matrix.

So, if "foamless" polyurethane exists and it is harder than polycrylic then I have found what I want. (Assuming the "foamless" polyurethane is just as easy to work with as polycrylic). This would make my glassed foam more dent resistant.

Cheers,

Chuck
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Old Apr 16, 2004, 09:44 AM
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New Hampshire, USA
Joined Oct 2002
299 Posts
Quote:
Originally Posted by Talon Driver
Is there a non-foaming substance that is styrofoam friendly and harder than polycrylic or WB polyurethane yet as easy to work with if not easier than polycrylic for glassing?
Chuck,

You might want to look at this stuff:

http://www.fxsupply.com/vanillacryl/vanillacryl.html

I've been wanting to order some to play with. Obviously foam safe, not as toxic as epoxy, non foaming, and drys to a hard surface. No idea what it weighs, or if it can be thinned successfully for glassing. I was thinking of using it to coat a plug, but it could be a decent surface finish coating too if it's light enough.

Rick
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Last edited by RickG; Apr 16, 2004 at 09:49 AM.
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Old Apr 16, 2004, 08:12 PM
OK, Who's Flying The Jet?
Talon Driver's Avatar
Albuquerque, NM
Joined Apr 2002
312 Posts
Vanillacryl

Wow! Interesting stuff. Let me know if you give it a try. Currently, I am investigating as I do not have another glassing project before me.

Cheers,

Chuck
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