Found this video, I think he’s a theatre decor making teacher. He uses gossamer fabric drenched in drywall joint compound, about two layers, to make a hard shape, and quickly makes texture on top of it using excess drywall joint compound. Awesome. Looks much easier than the papier-mâché clay options I looked at before.
Ideas for making bark texture:
- Using an icing bag to make stripes of bark texture, like this guy did with ferrocement
- Using a roofing nail to make “valleys” for the bark texture
- Perhaps use a silicon mould with some sort of release spray to make bark texture
- Just folding the fabric into little vertical ridges
Colouring ideas:
- Dark base coat, dry brush highlight on the ridges
- Could use dark pigment in the mix so I don’t need a base coat and damaged pieces aren’t so visible
- Just dissolve iron oxide pigment into thick paste and dry brush that directly onto wet project?
- Perhaps some white (TiO2) pigment to make even brighter highlights
- Black pigment in layer mix, brown pigment in extra “ridges” mix. Or just sprinkle some on the leftover mix used for ridges and barely even mix it in for some organic variation?
- Light base coat, wet brush darker colour into ridges
- Iron oxide brown in mix
- Dissolve carbon black into paste and wet brush onto wet project, wipe ridges
- Perhaps some extra dry brushed highlights
Other ideas:
- Flexible mixing container so dried gypsum is easy to remove sounds like a good idea
- Create a “folding” tree with a backing like this
- Score the backing material (cardboard?) to allow bending?
- Use same tulle fabric as backing material, no additional backing needed? Idea:
- Use vaselined ground sheet, drape first layer of tulle on
- Tape together with masking tape; tape lines are where the folds will be
- Paint masking tape into dark colour, or just use narrow duct tape
- Build up layers onto tulle, in between and perhaps slightly onto the tape lines
- Whole thing should detach from groundsheet when set and should bend on tape lines
- End product
- 200×36 cm half round tree? (folds and stores as 100×60 cm, 4x 15 cm sides, should weigh about 4.3 kg)
- 200×24 cm full round tree? (folds and stores as 100×80 cm, 8x 10 cm sides, should weigh about 5.7 kg)
- Alternatively, a different tree design that stores flat, e.g. two shapes that intersect like a cross when seen from above
- Alternatively, a tree design that nests for easier storage
- Half cylinder tree trunks built using my big plastic pipe as a mould
- More complete tree-shapes that nest like how clam shell pools nest. Would need to build a good mould to make sure they nest well
- Tree limbs
- Form around pool noodle or piping insulation
- Broomstick
- Use actual branches as base
- Rolled/scrunched up craft paper
- Shapes out of aluminium foil
Ordered:
- Tulle fabric – 0.3×91 m
- Carbon black pigment – 1.25 kg should also last a while. Recommended to mix in at 4.8% with concrete, up to 9.1%. I don’t need very black, and gypsum probably needs less pigment than cement, so it should colour 25+ kg of gypsum
- Iron oxide brown pigment – 0.45 kg. Probably not as potent as the carbon black, might still try mixing in with the gypsum, or I could just dry brush it on as a thick paste made with just water
- Gypsum, I ordered “Gyproc Blokkenwand Stuc” which is a gypsum plaster that can also be used as a block glue, it sets in about 2.5 hours (45 minutes working time) and is suitable for thin layers up to 5mm. Sounds ideal. Comes in 10 kg, or 25 kg which only costs 19% more. However, I don’t have much space to store things, so I got the 10 kg. If it works very well I can always get a bigger one later.
- Flexible mixing vessel 25 liters
Total cost €55.57. Assuming my projects will need two 2mm layers, the gypsum will make 3m² worth of projects, the fabric and black pigment should last at least 7m².
Next up:
- Picking up ordered materials and some cardboard
- Making space and putting down plastic groundsheet
- Testing:
- Tulle layers: 10×10 cm pieces with 2-3 layers of tulle onto vaselined cardboard. Use about 50 grams gypsum, 42.5 mL water
- Pigment/colour: bunch of 3×3 cm pieces using 5 grams of gypsum and 4.25 mL water each, plus different amounts of pigments. Use milligram scale & weighing boats – 7 mg accuracy gives about 15% relative error at 1% pigment, I’m ok with that.
- Texture: 30×30 cm pieces, should be about 350-500 g each
- Folding design: 45×60 cm piece with a horizontal & two vertical folds. Should weigh about 1 kg
- Non-flat surfaces: try on a pool noodle or something similar
To be continued.