Terrain sealer is a DIY mixture for sealing flocking, weathering powders, and preparing foam and MDF for painting.
After adding weathering, flocking, you need to add a sealer to lock those details in. Before painting MDF and XPS foam you need to seal it otherwise your layer of paint will just soak it up.
Unlike many recipes, this cheap mix involves no pigment unless you want to add it – making it perfect for sealing without changing the final colour too much!
What should you use for terrain sealer?
If you don’t mind spending extra money, there are commercial products out there, plus from the hardware store you can buy rattle can varnish and even “rubber in a can” sealer sprays intended for fixing leaks.
I would put those products in the category of final protection and/or for very precious projects. For simply persuading some XPS foam or MDF to take some initial paint coats, or to make your rush powder stick, consider this mixture in a squirt bottle or your (cheaper, not your best) airbrush.
Cheap, Clear, PVA Terrain Sealer
All of the recipes will come down to a mixture of PVA glue and water. In my mixture I add in some matte medium but NOT always any pigment.
- A shot of PVA
- A shot of matte medium
- A cup or two of distilled water
Use this as a starting point and see if you can spray a fine mist. If not you should add more water, if it does create a fine mist on some scrap material, does it look like watery milk or is it just like water? If it is too watery, add more 50-50 medium and PVA.
For stronger bonding and protection, you can up the PVA ratio or even skip the medium. Depends on your delivery method – an airbrush might refuse to put too thick a mixture through, and your squirt bottle might glob too much.
Flow aid (or dishwasher rinse aid) can help too.
For me, also, I don’t need flow aid, but if/when my spray bottle gets clogged I sometimes have to trim the feed tube as it can be a sign the solids are creating a sedimentary layer at the bottom of the bottle and clogging up the pipes. Ouch!
Do you want to add pigment? Go right ahead!
For me, however, I like to have a big batch of this sealer in a large dollar store spray bottle. I use it on and off all through a larger build.
Lots of people do like to seal and base coat in one go, and I can’t fault that at all. It does help to see where you have put it, or if you have missed any parts.
You can also add isopropyl if you like but I am not sure what benefit it is supposed to add except maybe drying time? When I lived in Alberta it was arid AF so I didn’t need extra drying power. I don’t personally add any alcohol or solvents, but some people like to do that and it is well worth testing out.