After reading a ridiculous number of posts and guides, and watching numerous youtube videos on basing, I decided it was time to undertake the monumental task of basing all 147 Tyranid models I own.
What I used:
Elmer's glue (just read somewhere that it's bad for this.. whoops)
Citadel Sand flock
Citadel Grass flock
Bestial Brown
Chaos Black
Codex Grey
Ghost Grey (Vallejo)
Acrylic Matte sealer
Cork
Everyone else here seems to paint their bases after applying flock/ballast, which confuses me. I've had it explained that if you don't prime and paint the base, it will look too realistic and detract from the model. However, I've found quite the opposite with my Hive Fleet Behemoth template nids. The genuine looking sand and grass contrasts the deep and vibrant reds and blues very well. Thus, I left painting completely out of the equation with the exception of painting the base bestial brown before starting anything.
It should be said that all but three of these bases already had models glued to them when I started painting and adding flock. Nothing short of frustrating most of the time, so in the future all my bases will be completed before a model is permanently affixed.
My procedure:
Paint the base with a generous ce and warm water. I used a size 6 flat brush for this, and it worked well on both large and small models. Very easy to clean with just warm water and a bit of gentle rubbing, but only use that brush for glue in the future.
Make sure the gluey moat of bestial brown. (not every base received this treatment, just to see how it would look with black instead)
Apply a coat of 1:1 white gluixture is spread relatively evenly over the whole base. The adhesive tends to draw itself away from the edges of the base if you let it sit for more than a few seconds.
Sprinkle a thick layer of sand flock over the glue. Shake it gently side to side to spread out the flock and get better coverage of the base. Tip any excess into the container and take the back of the base to shake any loose sand off. Then run a finger around the edge of the base to remove anything stuck to the side.
(Do
not dunk the base in the flock, this will ruin your flock over time and produces very poor coverage)
After around 30 minutes, the sand should be well in place. At this point, I cover approx 1/2-3/4 of the base with the same 1:1 mixture, and sprinkle the grass flock in the same way as the sand.
A note about the grass: This stuff will stick to everything, your fingers, the model, the sides of the base. I find it best to shake up the container before opening it. Loosens up the clumps and makes it a little less sticky, for some reason. Again, do not dunk the model in the flock.
Another 30 minutes, and your grass should be dried. At this point I used the acrylic sealer on any 25mm and slotted bases - no further work to be done on them. After the sealer dries, your base is well protected and ready for a model.
For anything 40mm and larger, at this point I start tearing up some cork board (found a roll of ~6 square feet for $3 at Michael's, will last me forever). The kind I purchased has adhesive on one side, which makes it spectacular for creating stacks of rock slab or just piles of broken rock. Tearing up 4-5 small pieces, then using the adhesive to stick them together works really well. After this, just a small bit of white glue (or other adhesive if you like) and some patience will give you rocks for your base.
Quick coat of sealer after the glue dries will give you the perfect surface for painting.
Thick coat of black (especially covering all the jagged edges), followed by a thin coat of grey, making sure to completely cover the flat surfaces. Dry brush some lighter grey over this, and you've got rocks which nicely contrast the grass and sand.
Again, this was just my first time trying basing. But with this method (long and arduous it may seem), I finished all my models in about four days, maybe 16 hours of work total. Appreciative of opinions or criticism.
Termagants
Hormagaunts
Warrior and Carnifex
Tervigon