Awards Earned: 1st Place, 8th Physical Science, PCA Science Fair 3rd Place, 8th Physical Science, ACSI Reg. Science Fair

Which type of paint or paint finish best protects metal from rust?

Indoor / outdoor paint will prevent rust better than an indoor only paint because the interior / exterior paint is probably prepared to be more durable against natural forms of destruction. Likewise paints with a glossy finish will perform better than those with a flat finish since the glossy finish will repel water while the flat finish will absorb water. Oil-based paints should preserve metal better because oil repels water, which is required for rust to occur, while water-based paints start the process of corrosion from the moment they are applied. But even water-based paints should be better at protecting metal than no coating at all.

I cut eleven pieces of low carbon steel and painted ten pieces with a variety of protective coatings. One piece was left uncoated as my control group. I also cut a piece of galvanized steel for an additional variable. I fastened each test piece to a long aluminum bar with clothes pins. The aluminum bar was bent so it would suspend the test pieces over a tub of salt water. I dipped them a minimum of two times each day in the salt water solution. I continued dipping the test pieces for nine days.

Control Group:
One piece of metal left uncoated.

Variables:
I applied different coatings to ten pieces of metal and added a piece of uncoated galvanized steel.

Materials:
Eleven 2.5 inch x 4.5 inch pieces of low carbon steel.
One 2.5 inch x 4.5 inch piece of galvanized steel.
Ten different protective finishes.
One paintbrush.
One 2.5 inch x 24 inch aluminum bar.
One plastic tub.
One cup of iodized table salt.
Three gallons of water.

My hypothesis was right in that oil-based coating performed much better than the water-based, the gloss finish protected the metal better than the flat finish and any finish was better than no finish at all. There was no evidence of the interior / exterior paint being superior to the interior paint. It may be that the manufacturer made this formula to protect against exposure to sunlight rather than moisture. If I were to do further testing, I would try different brands of the best performing coatings with both water and sunlight.

Matthew 6:20-21 says: "...store up for yourselves treasures in heaven, where moth and rust do not destroy, and where thieves do not break in and steal. For where your treasure is, there your heart will be also."

A lot of people today focus on just earning as much as they can in this life and not worrying about their afterlife. We should not focus on this life because everything we earn can be destroyed, just as rust destroys. We should realize that the only thing that really matters is what God sees in us.

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