Hard Coating EPS Foam and HDU

[joe]

Jennifer DeVos, in a previous thread, asked about techniques for hard coating foam. During the posts I stated it was possible to use Gel Coat on EPS Foam. And everyone jumped me. I'm glad they did because that wasn't exactly good information. However I visited my source of information and have good news. They are using a modified Gel Coat but epoxy is the base. It's extremely thin and made to spray. Sets up fast and is extremely clear. I'm not clear on the UV resistance.


http://i38.photobucket.com/albums/e115/jcrumley1/IMG_0054-1.jpg


http://i38.photobucket.com/albums/e115/jcrumley1/IMG_0055.jpg

This company manufactures surface coatings and gel coats for the space industry. I'll be posting more when my 5Gal order arrives.
http://www.axson-na.com/ (http://www.axson-na.com/)


Joe Crumley
www.normansignco.com (http://www.normansignco.com)

[tuck]

I hope Jim Brewer sees this, although I'm not sure how any hard coat can stand up over time to being knocked around, dropped and scraped.

Great research, Joe. I think there's a huge market for letters and such that are cut out of that pink insulation foam from the Home stores and this treatment could really be an up-sell.

[joe]

Mark,

I don't know how much you know about this kind of coating but the harder a surface is the more likely it will fracture. It's a trade-off. But you and I don't have the time to do all the experiments. Over the past four or five years I've worked very hard to get to this understanding. I've tried just about eveything. The biggest and most expensive mistake was with StyroSpray.

I've seen the results, first hand, with this gel coat and I'm a true believer. These folts make small aircraft for survelance and weather forecasting. They are made from an extremely thin and smooth eps foam market as Depron. It feels to me to be six or eight pound density. I'm understanding it only comes in thicknesses up to 1/4".

I'll be testing and report on these materials and others in a couple of month on the http://www.signtalkforum.com/ website.

I know I'll need be very accurate or Bill P and Gary A will be after me. HeeeeeeHeeeeee He He!

Happy Routing

Joe Crumley
www.normansignco.com (http://www.normansignco.com)

[bleeth]

Interesting stuff Joe. The 2108 in your shot is a laminating resin made to be used with cloth according to the company website. That would lead me to believe that like a boat, the 2108 is used over the "mold", which in this case is actually a body of foam, with a fine cloth and then sprayed with the gelcoat as a fill/smoothing agent that's much harder than something like Duratec. If not I would love to learn more about their process. There is an old axiom that epoxy will bond to polyester but polyester won't bond to epoxy.
I had the pleasure years ago of getting a tour of one of the Hydro race boat companies shops. Their laminating system was really cool. Instead of using hardener to kick the epoxy they actually used a combo of heat and UV. I had built off shore racers previously using a vacuum bag over a foam core and it was quite neat seeing the even more advanced high tech methods used for the Hydro's. But then this was in Seattle which has the technological home of Boeing at it's core.
On the UV thing I think they have developed some laminating epoxies that are more resistant to breakdown but still recommend coating with a UV inhibiting paint or varnish.

Point being that the impact and tensile strength actually comes from the 2108 laminating resin impregnating the fiberglass cloth and the gel coat, which would be one of their epoxy based ones, is less brittle than a polyester based one but is not where the real impact strength comes from. Or maybe they don't worry about impact strength. As fast as that little baby looks if it crashed it would be history even if it were solid Kevlar!
You're lucky to have neighbors like that. Are these the same guys doing the gorgeous statues you showed a few years ago?

Dave

[joe]

Dave,

I appreciate you input on this subject. You're far ahead of me. Here's the way they're working with these materials. With their Hotwire CNC they quickly cut out Depron foam and begin sticking it all together. The first prototypes are just that, trial pieces. They harden it off with several coats of the gel coat and begin stuffing the electronics and motors in. It's a little more delicate than I described. Now were ready to fly.

After the flight testings they get serious building a real plain, the tefflar is applied with the gel coat. Once finished it's near bullet proof. However from what I've seen this stuff will work for my application. All I'm looking for is a good hard undercoat.

I'll be posting more on the subject over at the sign routing forum. You asked about the previous postings of Steve and the crew maing the large 3D router images. Yes all the same artist are in the same building. Each one is helping the others on everything. I made my way through some huge 3D persons getting ready for their application of surface clay. That's where the deatil is applied.

http://i38.photobucket.com/albums/e115/jcrumley1/IMG_0058.jpg

Here's Steve working on some foam people.

Joe Crumley
www.normansignco.com (http://www.normansignco.com)

[bleeth]

Joe:
For your usage you will want to verify the "secondary bonding" of the gel. Whether epoxy or polyester based some have a surface charecteristic once cured that makes top coats of other materials (like paints and even more gelcoat) not adhere well unless the surface is sanded first. Others are made to secondary bond very well.
Resins developed, like the 2108 pictured, are called laminating resins because they do bond well when layered.

You got me on "tefflar". What's that? Kevlar? If it is, that's a woven fabric used for bulletproof vests. It is tricky to work with and sheer heck to drill through. When first developed the US Navy had plates of it put on the sides of ships but it didn't hold up as the resins they used at that time didn't hold the bond so it peeled in layers. They have learned a lot since then.

Dave

[joe]

Dave,

I've not had trouble with epoxy bonding to eps foam. My only problem was vertical application. I'll contact the manufacture to ask about adhesion to foam however from what I've seen on the models it seems to becomes one with the material. It almost looks as if it has a chemical adhesion. My Indian friend tell me "You gotta become one with the Gel Coat"

As you know HDU has so much texture a physical adhesion shouldn't be a problem. My friends here at Synopsis use tons of 3lb HDU which is very soft. Hardcoats like this are necessary.

I'm not sure my standards for signs need to come up to US Military submarine requirements. After all Dave, at my age, I'm offering a "Life Time" warranty on all my sign! It's my new sales pitch. What do ya think?

[bleeth]

Joe:
Epox on eps foam is no problem. It's the polyester resin that does it in.
I like the lifetime warrenty. Considering I'm nearing the same age when darned near every male in my family moved on "to that great workshop in the sky" (or maybe the other direction!) I might use that one myself!!
On the other hand, just building one sign that would take a 30-30 and have no damage could be a fun challenge.

"Bulletproof Signs by Joe"

:D

[gene]

i sure would like to see the finished products of them foam people :rolleyes: is there anywhere i can see a photo of them.?

[steve_g]

"Bulletproof Signs by Joe"

Out where Joe hails from, this could be a real selling point!

Steve

[joe]

The mob over at Synopcis uses Gelcoat on their 3lb HDU as opposed to epoxy. It gets much harder.
Dave is correct about fiberglas resin. It eats eps foam.

I've had lots of heartaches over hardening up EPS. I can make it look beautiful but never as strong as I would like. Here's an example.

http://i38.photobucket.com/albums/e115/jcrumley1/1.jpg

I've learned the hard way, a project like this should haved a MDO flace on both sides. The only time I use eps foam is in the center for depth.


Joe Crumley
www.normansignco.com

[letterman7]

I've played with this stuff in the past but don't do enough (any) foam work to warrant any kind of serious investment: http://www.volatilefree.com/hard_coats.asp

Bought the gun and a case of the hardcoat to see what it could do - makes a mess, but the resin is as tough as it gets. Once set it can be painted with any paint and primer system.

[joe]

Rick,

The panel I'm showing was sprayed with Sherwin Williams texture coat. It's very safe and not too expensive. The VF you tried out was, as you described, difficult to use and kills details. We've had it done to a couple of signs. When set up, like you say, it's hard and ugly.

Joe Crumley

[letterman7]

Joe, is that stuff usually in their stores or is it special order? I don't use 'house paint' on my signs so I don't get to SW at all, but that stuff looks like something I might play with!

[joe]

Yep, that's a SW product and they mix the color in it. That way when it goes on your finished.

It only comes in 5gals. and cost about $100. It's applied with a hopper gun.

Joe Crumley
www.normansigco.com

[taskins]

Joe-

Confirming what Dave said-I don't think you'll have any problem with the EPS foam/epoxy combo. That's what they make "epoxy" surfboards out of. As previously stated the surface will be hard but not structural without some cloth. Epoxies usually have little or no UV so they require a topcoat for exterior use. The surfboard guys use polyester clear coat but you can use any good polyureathane varnish or one of the 2K automotive clear coats as the top coat. Usually requires sanding between coats.

Conventional Gel coat on the otherhand is designed to be sprayed into a mold and subsequent structural layers laminated on top- the molded surface creates the finish. They also make "air" cure that will harden when applied to an exposed top surface. You can add wax/styrene mix to polyester laminating resin or gel coat to get it to harden to a non tacky surface suitable for sanding.

The stucco guys use a surface hardener sometimes too but I don't remember what it's called.

Tim

[terryjones]

Joe, Is this the product you are talking about from Sherwin-Williams?

http://www.sherwin-williams.com/wcm/idc/idcplg?IdcService=GET_FILE&RevisionSelectionMethod=LatestReleased&allowInterrupt=1&dDocName=SW-PDF-ULTRACRETE-MASONRY

[joe]

Terry,

I believe that's the product. It comes in three textures. I use the lightest, they call a sand texture. By the way, Harbor Freight sells one of the best hopper guns I've uses. It sells for $19. bucks.

Turn up the air pressure all the way and it goes on very smooth.

Joe Crumley
www.normansignco.com

[letterman7]

Ah! So essentially it's a DryVit type medium that you don't need a license to apply. Interesting... I'll be looking into that!

[terryjones]

Joe, Thank you. I have a brand new one still in the box. And thanks for the tip on the air pressure.