what would cause this?

[mvwood]

I went to look at a used machine the other day and it everything looked in order for the price and year (2012)but one thing caught my attention and the dealer had no clue. The dash lens had many small fractures throughout the surface. Nothing was cracked all the way through though. Anyone have an idea of what it could be from?

 

[twomany]

Ultra violet radiation.

It doen't just yellow plastics, it ages and drys and shrinks.

Stuff cracks when all those changes happen.

 

[Merlinhomeauto]

Looks like they used the wrong cleaner on the plastic , have seen many motorcycles windshields with the same problem.

 

[Lencho]

It is interesting to figure out the cause. In the end focus on the fix - price a replacement and factor that into the negotiation.

 

[Jpatrick]

Those cracks are likely thermal expansion/contraction, although UV degradation could be a factor. It's likely a sign the tractor has spent a lotta time outside and not in a garage.

The reason the pattern is in one direction (vertical) is that the plastic was probably extruded and gives the final plastic an anisotropic morphology. "Anisotropic" means it's not the same in all directions.

 

[twomany]

the effect is often called "crazing".

Crazy cracking. Plastics do that. it's not a problem worth fixing.

 

[Holleyman]

I've had clear plastic do that after exposed to brake clean. May be a chemical interaction

 

[manvstaco]

I tried cleaning a plastic face shield with brake clean and mangled it once. Couldn't see through it ever again