Hey gang! In this episode of Cooking with Blaze (trademark pending) I’ll show you how to create homemade plastic putty, as well as colored plastic cement.

First things first though – why do we want to make our own plastic putty? After all, we have a ton of commercial options to choose from.

  • First off, it’s easy to make and very versatile – we can make it thin and runny or near-solid. It’s a good alternative if you can’t get your hands on brand-name stuff where you live. Or if you are on a tight budget.
  • Secondly, as the name suggests, we make it with plastic. Once it cures, it’ll have same consistency as the part we applied it on. If you ever tried scribing on a surface that’s part plastic and part putty, you can probably see the advantage already.
  • Finally, it’s the best option for fixing damaged surfaces on unpainted kits. Unlike commercial products, it can perfectly match plastic of any color. All you need is the leftover runner said part came from.

In addition to plastic putty, we can use this method to prepare colored glue. It works exactly like the standard plastic cement, while also leaving behind colored seam. Quite useful for scratch building.

Now, let’s cook some up!

Plastic Putty & Colored Glue

First off, here’s the list of materials we’ll need:

  • Polystyrene plastic – We can use basic plastic sheet from a hobby store or old runners.
  • Plastic cement – Most brands will work, but I recommend Tamiya Extra Thin Cement or industrial-grade MEK (Butanone).
  • Sealed container – like spare paint jars.
  • Something to cut the plastic – like strong nippers, wire cutters or a hobby knife.
Tools we'll need to cook some putty.
We begin by cutting up some polystyrene. In my case – some 3mm plastic sheet leftovers and one of Astaroth Origin runners.

Try to cut plastic into rather small pieces. Bigger ones – like the ones I cut for this photo – will slow down the melting process somewhat.

Cutting up some plastic leftovers.
Next up, we add plastic cement. Remember – plastic cement is a glue that actually melts polystyrene, standard adhesives won’t work.

As you probably guessed, consistency of the final mix will depend on the plastic-to-glue ratio. Adding just enough cement to cover the polystyrene will result in a very thick plastic putty. Add just a few runner pieces to a large amount of glue for colored cement.

Don’t stress over the ratio too much though, just eyeball it. You can alter the mix later if you don’t like its consistency.

Now, it just needs time. Exactly how much time depends on the mix. My colored glue was ready in 2-3 hours, while the thick plastic putty needed over 20 hours.

Adding a little cement for the putty.Adding a lot of cement for colored glue.
Here’s how both of them looked after 24 hours. As you can see, white mix formed a thick paste, similar to basic 1-part putty. Red mix on the other hand is still rather thin, similar to standard plastic cement. It can be used as a glue or to fill small surface imperfections, similar to Mr.Hobby Dissolved Putty. As I mentioned, consistency can be easily changed at any point. Both mixes are all done.
Here’s an example of using colored glue. You can clearly see the red line going down the middle of this piece. 

It’s very useful for building symmetrical pieces, since you can use those as guidelines. Imagine building a sword from two pieces of pla-plate – with colored seam you can easily tell, where the edge should be and how far to sharpen each side.

Piece glued with colored cement.

And there you have it – cheap, versatile and simple to make homemade filler. 

6 Responses

  1. KageToTora says:

    This is brilliant.. I was building a cleaver for an Efreet the last week and this article is perfect. Really thank you

  2. Great tutorial. Just one tip i could suggest regarding below.

    “Now, it just needs time. Exactly how much time depends on the mix. My colored glue was ready in 2-3 hours, while the thick plastic putty needed over 20 hours.”

    If you need it ASAP, you could heat up the mix to reduce the melting time (as most chemical reactions do). How you would heat it though is up to you.

    • Blaze says:

      Well, I’d avoid heating it too much, as plastic cement (and MEK/butanone) are highly flammable. Though I suppose dip in warm water wouldn’t hurt.

  3. maxpayne92 says:

    hey thanks for the tuto but before i try it , can you tell me , if i use like the thick type you show us instead of putty , like for exemple to fill the gap along a gundam riffle, it just go like mr surfacer (or disolved putty) or it can melt the gun ?? and how much time can i keep this homemade putty in a sealed jar ? thanks for all the tips you show Blaze :)

    • Blaze says:

      Heya! I use the red one for seam removal and it works wonders. It goes on similar to Mr.Dissolved Putty and slightly melts itself into the plastic. Don’t worry though, it won’t damage the part. I wouldn’t use thick type for this, it’s harder to work with and mostly intended for filling big gaps.

      As for the shelf life, you can keep it pretty much indefinitely. I’m still using the same batch I made in November. Over time some cement might evaporate, but then you can simply add more and it’ll work perfectly fine once again. :)

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