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Hi guys! I have a question. I'm making big fruit slices out of pink foam board and paper mache. I covered a couple of them with masking tape first and think strips on top and a couple I just applied the strips with no masking tape and both of them lifted from the foam and made big air pockets. Funny thing is it didn't happen on the top part of the slice, but just on the bottom. Also I used a mixture of flour, water and PVA on a couple and then diluted PVA on a couple and they all turned out the same. Should I maybe paint the foam with diluted PVA before applying the masking tape and/or the paper strips??
It's not a big deal since it's on the underside, but it's driving me crazy I gotta figure it out because I have many more plans with this foam!
I don't know how to post a pic, but their are 2 layers of foam, the first layer is the face of the slice and the bottom layer is more like a donut or an "o" so that it can easily hang on the wall. It is the section in the middle of the "o" that seems to lift. Hope that makes some kinda sense lol.
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I'm sure you've already thought of the answer. I guess that one side of your foam already has a sealant on it so if you paint it all with a thin coat of PVA it should provide a bonding layer. With a good amount of PVA in your paste it should bond even without using the masking tape. I wouldn't use flour - dries brittle and attracts vermin - but wallpaper paste or (better still) CMC if you can get it.
Another method would be to make a cardboard construction as the base?
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Poor you. I know how frustrating it can be when this sort of thing happens.
I remember years ago, I had the idea of covering one of those foam round bases that shop bought pizza come on. Nothing stuck to it.
I'm sure Sue (Catperson) will be able to tell us what is in this type of material that deters adhesion.
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Pink insulation foam! Good stuff! Owens-Corning polystyrene foam: small, smooth grain, easy to carve, resistant to moisture absorption, various thicknesses.
Plastics have their own rules -- you must use adhesives that work with them, and most organic (flour, maybe CMC/carbo-methylcellulose) adhesives that were designed for paper or wood just won't work consistently with them.
Once you've got all your cutting done, coat the entire foam piece with PVA adhesive (aka 'white glue'), front, back, edges, diluted half and half with water, mixed well. Let dry. If you've gotten some parts to stick with the flour/water glue, leave it be and just coat right over it.
Now start applying your paper coating, using the same diluted white glue as your adhesive. Since the foam board is moisture-resistant, I would only apply one or two layers of paper at a time, then let them dry thoroughly, since they can only dry from the outside.
Using that foamboard can be addictive: you're always finding other things you can do with it! If you find that the white glue isn't holding well enough for other types of projects (including foam-to-foam), check out your local hardware store for the Loctite® brand PL 300® VOC Foamboard Adhesive. It is latex-based (low VOC - Volatile organic compounds), uses water for clean-up, and will also stick to many other types of surfaces, including wood, gypsum board, concrete and brick, etc. But it only seems to come in those large tubes that require a caulking gun to dispense it ($7-10+, reusable forever; sample photo: http://www.amazon.com/Newborn-DC012-Pre … amp;sr=1-3 )
Sue
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AWESOME!!!! Thanks so much for all your input!
I went ahead and just put a good layer of celluclay over it for the 4 pieces I have right now, but am definitely going to play with some more and will coat it with diluted PVA first.
And David, it's possible that I may have diluted it a bit too much when I used it with the strips.
I don't know why I always want to use a mixture of flour, PVA and water, I think it's just I like the texture of it. And most of my stuff I have been covering with a thick layer of paper clay anyway so I guess it wouldn't matter much then. But I definitely got critters when I used straight up flour and water and paper strips! They ate right through it!
So anyway, the fruit slices are being made to hang on the wall so I had planned on just leaving the backs paper strips and the sides and white parts of the fruits would be celluclay because it resembles the texture and I have a bunch of it lol! I really didn't want to go through all that work of covering the backs too, but too late I'm doin' it!
So the "juicy" parts of the slices are still the smooth paper strips and I plan on gessoing the heck out of them and then applying a layer of Heavy Gloss Gel and sculpting the "pulp" into the gel. I love playing with that gel and when I paint it I will make a wash and it will still be transparent in places and I think when I add a gloss varnish to the fruit sections it will look really JUICY! The rest I will coat with matte or satin varnish.
Can't wait to see how they turn out!
Thanks so much for all your input and I will let you know what happens and maybe do some more experimenting and share the results of that too!
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I finished them and they turned out really nice! If I make more I will definitely change a few things lol. Trial and error! I just posted them in my gallery if you would like to take a look! 
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Skwirl, I would certainly like to take a look, but the gallery goes by names, and I have a hard time remembering my own, much less anyone else's.
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Oops sorry I just saw this! My name is Shirley Byers (aka skwirl)
I would appreciate your feedback!
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Those are good looking juicies! Very realistic and your coloring was excellent!
Sue
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Thanks Sue!!!!!!!!!!
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