Foam…foam everywhere

[EvanWRapp]

We recently did a large project which involved a tremendous amount of working with foam. Specifically, EPS in mostly 1 pound but some 2 pound as well.

It was a type of project that we aren’t well acquainted with but we somehow managed to pull it off and it looked incredible. I won’t be able to share pictures until the show opens in 2020 unfortunately. I would however, like to start a conversation about working with foam. I don’t claim to be a foam master… at all. But I did learn quite a bit with this project. So I’ll kick it off with a few observations and end with some questions. I’d like to get some feedback about other’s experiences so please don’t feel like you “don’t know enough” to reply or any of that hogwash.

• Foam gets everywhere.
• Sharpen those filet knives.
• Cut away from yourself with said filet knives!
• Hot wires are great but super finicky. I ended up making jigs out of scrap material to clamp to pieces of foam so that I could make nice mitered corners. This took some practice but it really was the best way to cut CNCed columns and trim.
• Use a hot knife properly. Ours needed to be sent out for fixing.
• Running foam through a table saw or chop saw is a real roll of the dice. It was wonderful for straight cuts but terrifying when it would catch the blade and throw it or mess up that one important piece. It seemed to get tricky if you weren’t moving fast enough because it would heat up and catch the blade. Go too fast, plan on disaster. Saws and foam are just terrifying. That’s all.
• Adhesives make a mess. Set aside a place to spray the adhesive.
• Ventilation is your friend when using adhesives, hot wires/knives.
• Other tools I found to be very useful throughout the process – pull saw, palm sander, rasps, sharpie markers aplenty.
• Measure twice, cut once. Unfortunately we had a lot of custom cutting to get CNCed pieces to fit properly. I spent copious amounts of time going up and down ladders and lifts. It was a lot of finding angles, making cuts, dry fitting, cutting more, dry fitting, cutting more, dry fitting, spraying adhesive and final fitment.
• Get rid of those adhesive “spider webs”. We had a company come in and hardcoat with a polyuria and any small spider webs became the most hideous looking things with the coating. It is much harder to cut through the hardcoat to remove the webs than it is to properly clean them off beforehand. This leads to….
• General clean up of the scenery before hardcoat. Compressed air worked well to blow off loose pieces of foam. Shop vacs helped as well. Do all you can because those loose pieces become unsightly once hard coated.

There are a few quick observations for now. I’m sure I will remember more to be added later. In the meantime, I have some questions for you all.

• Any preferred knives you use for cutting?
• Any particularly good techniques you use with the hot wire?
• What is your method of cleaning the scenery/props before paint treatments?
• What do you use to coat the raw foam before paint?
• Any big differences you notice in carving with 1 pound versus 2 pound foam?
• What adhesive do you use for foam?

Hopefully we can get a good conversation going here for everyone to reference in the future. Foam seems to be one of those things where everyone has a special little trick for something or other. So lets compile this info and do what we do best here at the Guild…. be a helpful community!

[EvanWRapp]

I just got a new sharpening tool for my fillet knives. It makes a world of difference.

Finished another small project making some stone speaker covers. I’m curious what foam coatings others use? Flex-coat, foam-coat, Jaxsan, etc?

[Greg Widdecombe]

Jaxsan Guy here, if you want to try some Jaxsan, I can help by sending a small sample for you to try and make your own comparisons. Just let me know through the web page email.

[Nicole Deibert]

I’ve moved away from Jaxsan, mostly because trying to get it shipped to Canada during the winter often resulted in frozen product when it should have been shipped heated. I’ve now started using a few products from Robson’s Thermal out of Whistler, BC.

When I’m carving foam, be it the pink/blue insulation foam or the white foam, there are always some spots where you have gouged too far. A product I use as a smoother/filler is Robson’s Foam. It’s a super lightweight product that easily fills in the gaps, it’s sandable, paintable, if it’s spread thinner, it does have a little flex to it. Water cleanup.

Then to protect my pieces, there are 3 choices of elastomeric products:

• RT-38, which is a more liquid elastomeric coating, but I’ve found that it’s thicker than Ben Moore Ultra Spec Elastomeric or Cloverdale Towerthon Elastomeric.
• RT-10, which is very thick, it’s white, and can be thinned (as any of these products can) and has a great flex to it.
• RT-29, this product is most similar to Jaxsan in consistency, but it has little fibres in it for more strength. This product is grey, thinnable. I’ve mixed various substances into it for texture: sand, sawdust, crushed walnut, cork. You can thin it out quite a bit, especially if you add a texture like cork to it.

The best thing with Robson’s Thermal is that a good bunch of their products are freeze/thaw stable. This is a super bonus, especially in Canada. The price is better for us in the long run – I think a gallon of RT-29 is about $50.

I realize that I’m going to have to do a video on Robson’s Foam because it’s a hard product to explain, but it’s SO AMAZING.

[Zaling]

Oh foam. We usually do a few large scale foam projects a year (we’re carving an 8’x8’x4′ deep jack o lantern facade next week!).  I’d love to hear more about how you found a place to hard coat for you.  It’s something we struggle with for really crisp projects.

Any preferred knives you use for cutting?

Click knives are great and somewhat flexible.  Electric turkey carvers or bread knives are useful too, especially for upholstery foam. One member of my crew really likes small chain saws, but he’s also a stump carver so there’s a bias there.

Any particularly good techniques you use with the hot wire?

Make a guide using scrap lauan and clamps works really well. We have an 8′ wire with two paddles, so we do team hot wire work. Good communication is key! Practice on scrap for tricky cuts. I try to avoid melting foam whenever possible. Respirator cartridges don’t offer complete protection, and the ventilation in my shop isn’t great.

What is your method of cleaning the scenery/props before paint treatments?

A lot of swearing. Shop vac with the bristle attachment. Tape folded back on itself.  Lint roller.  We do a lot of clean cuts here so that helps cut down on the little beads getting everywhere.

What do you use to coat the raw foam before paint?

Ah yes.  Hard coating is my greatest nemesis.  I’m horribly allergic to styro spray, although it is a good product so long as your humidity is high enough. I tried Armor coat from Polygem and hated it (too brittle). I’m using aqua resin and aqua veil for the jack o lantern next week. Smooth Ons’ Epsilon and Epsilon Pro are both good, but expensive. I’m also a fan of making goop from latex paint, powdered joint compound, elmers glue, and a little water.  You can add texture mediums to it, and adjust the consistency by altering the ratios. Plus since it has paint in it it acts as a basecoat.  I’ve done some great barn timbers using that mix.

If anyone has other hard coat suggestions I’d love to hear them!

Any big differences you notice in carving with 1 pound versus 2 pound foam?

2 pound is little less messy and holds detail better.  We almost exclusively use 1 pound though.

What adhesive do you use for foam?

Green glue (3m fastbond contact adhesive).  You can also use it to prime ethafoam backer rod so it holds paint.

 

[EvanWRapp]

Greg: We have Jaxsan around the shop that I just used for the rock project. Thanks for the offer to send some! I can’t say that I noticed much of a difference between Jaxsan and Rosco Flex Coat. They both worked well.

Nixpaints: I am super curious about the products you’ve mentioned. I might be trying to track them down to try out!

Zaling: Lot’s of good info there! We found a company that typically sprays truck bed liners. They brought their own equipment into the shop and sprayed after hours for us. We have a scenic in house that has a really bad allergy to these types of products so we didn’t attempt anything on our own. This individual had a really bad reaction to a Smooth-On product for a foam coat we did about two years ago. The product was great. Her reaction to it wasn’t. The hardcoat is nasty stuff and also VERY finicky. From what I gathered, the polyuria is a typical truck bed liner and so perhaps you could reach out to any local companies that do truck bed liners.

Okay…. I have another question

Preferred method for attaching scrim to a cutout on a piece of foam?

[Nicole Deibert]

I’ve posted the link to their website. Some of the products I’ve mentioned aren’t listed directly on their website. Fear not! They exist. Let me know if you need any further info on the products.

[Alyiece Moretto-Watkins]

Hey Evan,

In Nov. 2019 and Jan. 2020, I worked on two separate projects that required A LOT OF FOAM WORK, with your questions in mind, here is what I took away…

Any preferred knives you use for cutting?

Large Box Cutters for finer details

Japanese Pull Saws

Battery power Sawzall

Any particularly good techniques you use with the hot wire?

Never use it, rely on sculpting and sanding for most control.

What is your method of cleaning the scenery/props before paint treatments?

Brushes and Shocvacs

What do you use to coat the raw foam before paint?

<i>We used a mixture 1:2 ratio of Joint Compound and Elmers Glue just for painting  but coated surfaces in Green Glue for pieces that characters interacted with.</i>

Any big differences you notice in carving with 1 pound versus 2 pound foam?

What adhesive do you use for foam?

GREAT STUFF…actually worked out GREAT! We even used it to create additional texture when applied directly to the surface, it cut away and was able to be sanded.

**Trying to attach pictures but not going so well…

[EvanWRapp]

I’m curious about the JC/Glue mixture for coating the foam.

Thanks for the good info!

[JennyHitmar]

I’m reviewing my goop recipes for my class, and stumbled upon the Susan Crabtree text recommendation for joint compound and water based contact cement.  Does contact cement give better foam results for joint compound and white glue?

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