Zinc pest question- is this it... or simply a poor casting finish? K-line K623-4461 die cast Virginian hopper

Looks more like surface corrosion that was painted over or moisture got under the paint layer. Could be pest, but usually pest is indicated by swelling/cracking. Either way, the paint has lost it's bond with the base metal and that is why it is bubbled up like that.

This is "paint rash" which is both surface contamination prior to painting and/or outgassing of the solvents in the zamak.  The casting was not properly dried after casting and cleaning.  Very common of the Korean sourced scale diecast locomotives.  And this also plagues the diecast model car industry.   

Thanks for the analysis and feedback. Due to the lack of consistency and cracks, I was hoping the car would not crumble one day into oblivion.

I suppose you could use this surface quality to your advantage if you were to consider weathering the car.  After all, it didn't take much use of these cars in service to develop bumps, dents, wrinkles, etc..  There are some forumites that are quite skilled at weathering...like SIRT.  Perhaps they might offer suggestions along that line?

Just a thought...FWIW.  You know the ol' adage...Have a 'lemon'?...Make lemonade!

@Mike W. posted:

This is "paint rash" which is both surface contamination prior to painting and/or outgassing of the solvents in the zamack.  The casting was not properly dried after casting and cleaning.  Very common of the Korean sources scale diecast locomotives.  And this also plagues the diecast model car industry.   

What solvents are in die cast zamak? ……can you explain how a casting isn’t properly dried??…I did not know molten metal “dried” …….I always assumed it solidified. Perhaps you can enlighten the rest of the class??..

Pat

Good question, I had to look up Zamak too, interesting summary in wikipedia. 

@harmonyards posted:

What solvents are in die cast zamak? ……can you explain how a casting isn’t properly dried??…I did not know molten metal “dried” …….I always assumed it solidified. Perhaps you can enlighten the rest of the class??..

Pat

I would think he is referring to the cleaners used to clean the metal after it is molded. There are things like fingerprints and mold release agents that need to be cleaned before something is painted if properly prepped.

Beneath the I in "GIN", is that a crack starting between those two rows of rivets? It doesn't look like a paint run from here.

Are hot wheels and Mattel die cast cars made out of the same material or process?  There have been a few hundred pass thru my house and I never saw or noticed any cracking or deterioration. 

I really liked these cars - i bet I have seven or eight.  None have shown any problems like that.

Ignore it - run it until it crumbles - or bead-blast, repaint, and decal it.  Either way, still a fine model, and almost as good as the Lionel 714.

@nickaix posted:

Beneath the I in "GIN", is that a crack starting between those two rows of rivets? It doesn't look like a paint run from here.

Ouch, good find, that is a crack.  There is a gusset on the inside at that spot but the crack is not visible on the interior.  Let's hope just a casting defect too.

@bob2 posted:

I really liked these cars - i bet I have seven or eight.  None have shown any problems like that.

Ignore it - run it until it crumbles - or bead-blast, repaint, and decal it.  Either way, still a fine model, and almost as good as the Lionel 714.

I like them also but only have two. That is the current plan, let's hope the issues are cosmetic and the crumble point is far into the future.

@dkdkrd posted:

I suppose you could use this surface quality to your advantage if you were to consider weathering the car.  After all, it didn't take much use of these cars in service to develop bumps, dents, wrinkles, etc..  There are some forumites that are quite skilled at weathering...like SIRT.  Perhaps they might offer suggestions along that line?

Just a thought...FWIW.  You know the ol' adage...Have a 'lemon'?...Make lemonade!

I have not weathered anything but this is an idea! 

Correctly stated above.  These are cleaners and the casting is then heat dried.  If rushed the porous zamak traps the solvents and after painting they slowly push their way out.  Of course paint may show blistering prior to the adverse reaction cracking the casting as noted in zinc pest issues.

Upon closer look of the hopper that line below the GIN does look like a warp/crack and that could indicate zink rot.  Is their any warpage to the car when looking across the length?

Picks of paint blisters on Lionel Korean sourced locos from the early 1990's...the Turbine and Southern Mikado.  The casting itself was solid. Note the blackening chipping of the flanges of the Mikado.  Same issue happened on the diecast frame of the 1990 Pennsy Burro Crane from 1990ish.  Probably a Korean casting as well.

@aussteve posted:

Are hot wheels and Mattel die cast cars made out of the same material or process?  There have been a few hundred pass thru my house and I never saw or noticed any cracking or deterioration.

They are.  The issue on diecast model cars has been mostly the paint rash.  And the more toylike the item the thicker the paint.  Hence oddly the scale models are most affected.  As its harder for the gases to push through the thicker paint.

I will express my opinion that in modern times...since the 1980's there is absolutely no excuse for zinc rot or paint rash to occur on any of these products...it is very easy to prevent on the manufacturing side.  If Postwar Lionel can get it right then anyone else can.  I do think some diecast parts were used on the 1945 Lionel freight set that were carryover from prewar times and those did show zinc rot.  Like the pilot on the 224.  I will post some pics of that later.