Yellow tree from new amt kit

[MrMiles]

I just received a new sealed amt kit of a 67 mustang fastback. However there is one entire tree that has yellowed. Has anyone seen this before. Is this something I should try to have amt replace or do you think it's ok

[Dave Van]

No telling what plastic the Chinese used. If it's not brittle or super soft I'd think it's OK. 

[charlie8575]

I agree with Dave. Take a couple of pieces of the sprue frame, and see if it takes glue acceptably. If it does, you'll probably be okay.

I would advise washing all the parts first, though, to make sure it's not mould release or something like that.

Charlie Larkin

[ctruss53]

I would not be concerned at all. Just use it.

[1972coronet]

9 minutes ago, charlie8575 said:

I would advise washing all the parts first, though, to make sure it's not mould release or something like that.

That was my first thought : mould release agent. That stuff takes on a Cosmoline appearance when it sits for a while. 

[charlie8575]

1 hour ago, 1972coronet said:

That was my first thought : mould release agent. That stuff takes on a Cosmoline appearance when it sits for a while. 

It's not far removed from Cosmoline...or Pam, for that matter. And both will stain with a yellowish color, so even if it's clean, it may be discolored. Keep that in mind.

Charlie Larkin

[peteski]

Funny thing is that I have heard or read from multiple sources that no mold release agent is used for injection molding polystyrene. Yes, I have seen some amber "stuff' on some model it parts too, but I wonder if it is just some stray lubricating il from the injection molding machine.

It would be interesting to see if the yellow  cast can be washed off by scrubbing the parts with soft brush and some warm water and dishwashing detergent.

[Dave G.]

It could be the last plastic run was yellow and some remnants are left in the lines as this one ran off. Course I have no idea if that's how it even works but if so it might explain the yellow that should be white.

[Dpate]

Let it sit in dawn for a few and I bet it’ll get whiter lol

[OldNYJim]

I’ve had some AMT parts like that from new(ish) released kits…no cause for alarm based on my experience…

[atomicholiday]

It's almost certainly just a different batch of plastic.   I wouldn't sweat it.   As said above,  wash it like you normally would and go for it. 

On 6/14/2023 at 6:15 PM, Dave G. said:

It could be the last plastic run was yellow and some remnants are left in the lines as this one ran off. Course I have no idea if that's how it even works but if so it might explain the yellow that should be white.

Usually this would come through as a noticeably different colored streak.  You know the lines you see in kits molded in different colors other than white?   Particularly silver?   It would look similar to that,  with the streak being the different color.