Hello

Archives
Posts: 559
Joined: Sat Oct 31, 2009 1:36 pm

Hello

Postby Archives » Sun Nov 01, 2009 4:13 pm

K
Registered: 09/28/06
Posts: 1
09/29/06 at 12:26 PM
Reply with quote #1

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Hi Everyone,



I resurrected my old Creepy Crawler/Mini Dragon/Fun Flower/..... sets a couple of years ago. My kids love them and fortunately I had a good supply of the original goop. We are to the point now however where everything is purple or black - so I started shopping the Internet.. and here I am.



If you don't mind I have a couple of questions:



I have a lot of small bubbles in our creations. I had chalked this up the the age of the goop, but I read in one of your threads that oxidization can cause this. If that is the case, is it due to the surface roughness? The oxidation on my molds is not obvious, it is just a dull tint on the metal.



I read here about different cleaning methods and about nickle plating. Last weekend my kids had the set out and I decided to try sand blasting a particularly filthy mold. I used low pressure and a fine grit sand. I worked great and didn't appear to remove detail, but it does leave a dull surface - indicating some roughness.

Unfortunately I didn't get any goop into that mold to see how it worked. But until I get new goop, if it bubbles I still won't know if its the surface or the age of the goop.



Any comments?



My sand blaster was inexpensive. This may be an alternative to cleaning molds for those interested in plating them, because it cleans so well. The plating will return a smooth surface. I'm not sure if I want to go that far with my molds yet.



I may try glass bead or another abrasive other than silica sand to see if I can get a smoother finish.



Anyway, it seemed like there is a lot of knowledge here and I'm grateful for any advise. (I have already leaned a lot from previous threads).



Thanks,

Keith

Archives
Posts: 559
Joined: Sat Oct 31, 2009 1:36 pm

Re: Hello

Postby Archives » Sun Nov 01, 2009 4:13 pm

dr_goop


Registered: 01/21/06
Posts: 44
10/01/06 at 07:48 PM
Reply with quote #2

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Hi Keith,

it doesn't take much oxidation on the molds to cause those bubbles. Most of the time with oxidation the bubbles are just on the surface of the creepy you are making. If you are using a translucent type goop and notice bubbles in the middle, often, thicker goop will leave bubbles, and those would not be due to mold oxidation.

Archives
Posts: 559
Joined: Sat Oct 31, 2009 1:36 pm

Re: Hello

Postby Archives » Sun Nov 01, 2009 4:13 pm

chuck
Registered: 01/27/06
Posts: 27
10/05/06 at 10:42 AM
Reply with quote #3

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Yo,

Blasting the the mold with any abrasive media like glass beads, aluminum oxide, silica sand will open the surface of the mold and can expose some porosity in the casting. Blasting will clean them up, and they will still work, but you lose a bit of the surface doing this and the fine detail in some of the molds. Die casting most often produces a smooth outside surface. If you were to cut most castings in half without smearing the metal, you would be surprised at the amount of porosity you will see.

It is true about the different vendors that cast the molds for Mattel, different alloys sure show up after the years. Have you ever noticed the amount of blisters that you see on the Peanuts molds? Those blisters on the surface are from the casting process, little bubbles of gas generated during the shot, that are compressed while the die is closed. If the die is too hot or opened too soon, the pressure from the trapped gas bubble near the surface will "pop out" and form the surface blister.

You have to remember in the 60's, Die castings were done manually, in that the mold was manually oiled, the metal was hand ladled into the shot sleeve, the die halves were closed by the die caster. Then the shot was made. The cycle time varied, the heat in the die and oiling,and so did the characteristics of the casting, this caused some inconsistency of the finished casting.

Now that I veared off the topic, I would use abrasive cleaning as a last resort on a mold. Once the smooth surface is disrupted, the only way back would be hand polishing,(Hours and hours) which could create a smooth surface, as long as there is not porosity exposed.

Chuck


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