How to clean unsightly copper tarnish

[FluKanuck]

Hello all,

 

I'm working on the Amati Pegasus Kit right now. It's my third-ever kit, and first with copper plating. I coppered one side, and then... along came a baby. The kit has sat for 7 months and unfortunately has developed some ugly tarnish on the finished side. I was planning on varnishing it all nice a shiny for display. Is there any way I can remove the tarnish and restore its shine?

 

Please ignore the ineptitude of my handiwork, I tried my best

 

[BenD]

A common brass and copper cleaner from the grocery store should do it.  I used a product called Brasso. Your coppering looks pretty good, just needs a good pollish.👍

Before. 

After.

Edited August 22, 2023 by BenD

[Bob Cleek]

Well, never was there ever a ship with a completely shiny coppered bottom, so I suppose your choice to have it shine is a stylistic one.  I've polished more than my share of brass over the years. Here's a review of options from the really tough jobs to the easy ones. I wrote this before I saw BenD's post. If he says Brasso alone did that job for him, I'd definitely say, go for it! The "rub" is the rub, though. If your plating won't stand up to the rubbing that polishing requires, some of these products which work chemically rather than mechanically with an abrasive may be helpful.

 

The first caveat is that I have no idea what you used to glue the plates down, so I can't say for sure that they won't come falling off if you just dip the whole hull in a de-oxidizing solution. That would be a relatively easy fix, put perhaps wreak havoc with the hull structure itself if it's plank on frame or bulkhead rather than solid wood. These suggestions should be taken with a grain of salt (which I think will also work) and always, always test these methods out on a sample piece before using them on the hull itself. 

 

All of these methods employ chemicals which breakdown the copper oxide tarnish. They work chemically and hard, rough rubbing should not be necessary. Repeated applications will be helpful in removing stubborn tarnish as there is some degree of "neutralizing" as each does its work. Take your choice, in order of ascending effectiveness:

 

1. Mix five parts water, one part vinegar, and add salt until the salt stops dissolving in the mix. Apply to the copper surface with a soft cloth to clean off the copper oxide, then rinse well. A soft toothbrush or cotton swab can be used on uneven surfaces. This is the cheapest, and probably mildest solution, but also the least effective.

 

2. Use Simple Green all-purpose cleaner. It's a great cleaner and will also remove copper oxidation.  It's a mild liquid "soap" with a pleasant aroma commonly available anywhere cleaning supplies are sold. It contains a mild amount of citric acid. It's not particularly aggressive, but repeated applications will remove copper oxidation. See: https://www.walmart.com/ip/Simple-Green-All-Purpose-Cleaner-Concentrate-Spray-Bottle-Original-32-fl-oz/22301219?wl13=1755&selectedSellerId=0&http://clickserve.dartsearch.net/link/click?lid=92700060762254883&ds_s_kwgid=58700006715445296&ds_s_inventory_feed_id=97700000003583668&ds_a_cid=654818135&ds_a_caid=13956209185&ds_a_agid=126452889113&ds_a_lid=pla-1392082700544&ds_a_cid=116919406&ds_a_caid=361575031&ds_a_agid=120066732282

 

3. Use Barkeeper's Friend copper cleaner available online or from many stores. It's sold for polishing kitchen pots and pans. It comes in two forms, powdered and as a cream. Pick your own poison. I find the two equally acceptable. Follow the instructions on the container. Apply to the copper surface with a soft cloth to clean off the copper oxide, then rinse. As with any of the acidic cleaners, the longer it stays on and wet, the longer it works. You won't get far expecting instant results with acidic cleaners. Give them time to work. Barkeeper's Friend recommends waiting a full minute before rubbing it off, as I recall. A soft toothbrush or cotton swab can be used on uneven surfaces. This product is not as aggressive as a stronger solution of citric or oxalic acid and probably contains some other "magic ingredients" that their advertisements will tell you make their product better than the rest. See: Amazon.com: Bar Keepers Friend Powder Cleanser (2 x 12 oz) Multipurpose Cleaner, Stain & Rust Remover for Bathroom, Kitchen & Outdoor Use on Stainless Steel, Aluminum, Brass, Tile, Ceramic, Porcelain & More : Health & Household and Amazon.com: Bar Keepers Friend Soft Cleanser Liquid (26 oz - English/Spanish) - Multipurpose Cleaner & Rust Stain Remover for Stainless Steel, Porcelain, Ceramic Tile, Copper, Brass, and More (2) : Health & Household

 

4.  Use CLR Cleaner ("Calcium, Lime, and Rust") as directed on the bottle. This product is sold primarily for removing rust and calcium deposits built up on plumbing fixtures. It is available in most hardware stores. It is a harsh chemical product that contains citric, gluconic, lactic, glycolic, and sulfamic acid. Don't ask me what all these acids are for, but this stuff is definitely the thermonuclear option! Use as directed on the bottle. It can be diluted with water for a less aggressive effect. You may want to experiment with varying strengths to see which works best. As with the rest, a soft cloth, toothbrush, or cotton swab should serve to apply the stuff. See: Amazon.com: CLR PRO CL4PROEA Calcium, Lime and Rust Remover, 28 oz Bottle : Health & Household

 

5. Mix a solution of citric or oxalic acid (available in paint and hardware stores as "wood bleach) and water following the instructions on the container. Apply to the copper surface with a soft cloth to clean off the copper oxide and rinse off. A soft toothbrush or cotton swabs can be used on uneven surfaces. Wear surgical gloves when handling this mild acidic solution for extended periods of time. It won't harm bare skin, but prolonged exposure will cause delayed burns of the sensitive tissues under your fingernails, causing indescribable agony for an interminable couple of days following overexposure. (Don't ask me how I know this!) See: Buy the Savogran 10501 Wood Bleach, Concentrated ~ 12 ounces | Hardware World and Amazon.com: Pure Original Ingredients Citric Acid (1 lb) Eco-Friendly Packaging, Natural, Food Safe : Health & Household

 

After removal of the oxidation, you may wish to polish the copper to a higher shine. You may wish to try any copper polish for the job before using "the hard stuff" above. In fact, if the oxidation is slight, you may accomplish the finish you want using a copper polish alone. However, I may will run into some difficulty in trying to do so, though, because most polishes contain mild very abrasives and work by abrading the surface and your surface is decidedly not smooth. Their polishes' effectiveness will depend upon the surface's ability to withstand rubbing. Any copper polish is fine. Brasso (a cream,) Flitz (a paste or cream,) and Nevr-dull (an impregnated cotton wadding and USN bosuns' favorite) are all proven winners and folks each have their own preferences. See: Amazon.com: Brasso Metal Polish, 8 oz Bottle for Brass, Copper, Stainless Steel, Chrome, Aluminum, Pewter & Bronze, 8 oz (Pack of 3) : Health & Household, Amazon.com: Flitz Multi-Purpose Polish and Cleaner Paste for Metal, Plastic, Fiberglass, Aluminum, Jewelry, Sterling Silver: Great for Headlight Restoration + Rust Remover, Made in the USA 1.76 Ounce (Pack of 1) : Health & Household, and Amazon.com: Nevr Dull NEVER DULL POLISH 5OZ : Health & Household.

 

(Full disclosure: I don't own any Amazon stock. I just use their links to identify the stuff. All of these products should be available in any hardware store or even many supermarkets.  )

 

After you've polished your coppered bottom (making sure there's no polish residue remaining on the surface... perhaps easier said than done,) it will immediately begin to tarnish again, so coat it with a real clear gloss lacquer (and not a varnish which can yellow.) This is not a job for weak "eco-friendly" coatings. It's worth risking cancer for. (Just kidding... use only in a well-ventilated area... and all that.)  Apply in multiple light coats, rather than thick coats. It's sold in spray cans if you want to make your life easier. You must thoroughly coat the surface with the lacquer, though. Even the slightest uncovered area will continue to tarnish and look terrible against the contrasting bright shiny polished copper. In fairness, I have to add that I've seen a lot of professionally lacquered brightly shined copper and brass items over the years and it seems that after a certain number of years, depending upon the local environment, they tend to develop tarnished black "spots," sometimes called "the pox," beneath the lacquer. This is probably a function of oxygen permeating the coating in some fashion. Manufacturers always lacquer coat their bright work because that keeps it looking "just polished" on the shop shelves and that can be many years, but, eventually, sooner or later, "the pox" strikes and there's no cure but to strip the lacquer from the piece entirely and keep it "bare" and polished regularly. This actually looks better than the factory lacquer because the detail doesn't polish as well and is thereby highlighted, but you have to keep up with the polishing. In the case of a rough-surfaced delicate miniature coppering job, you will probably never be able to strip it and refinish it short of destroying it. This will be your one shot at it.

 

I must say that trying to polish a rough-textured surface like you've got there may prove to be an exercise in futility. You will have to polish it all, including every nook and cranny. Alternately, you may achieve a rather nice antiqued effect if the polishing isn't uniform, with darker, tarnished areas in the edges of the plates accenting them visually. 

 

Do remember to experiment and test your choice of methods before you hit the model itself. This is the sort of thing that is really easy to end up looking a lot worse than better if it goes sideways. 

 

I get it that you like "shiny," but you will not go wrong if you allow your copper to tarnish naturally to a "used penny" color. That's how it looks in real life after it's been in the air for a while. Exposed for longer and it will become green like the Statue of Liberty.

 

 

 

Excellent forum post on painting faux coppered bottoms: 

 

 

 

 

Edited August 22, 2023 by Bob Cleek

[FluKanuck]

Would love to mark you both as the solution thank you!

 

I've glued each one with CA glue. My wife actually has barkeepers friends copper stuff, so I will give that a shot first. 

Thank you both for your answers! I know they were weathered in real life, but I want mine to be shiny

[allanyed]

Picture of USS Constitution copper plate says it all regarding color.  I realize many folks won't like the look of weathered copper, but it is another choice.  Note the number and size of the nail holes rather than the over scale rivet-like bumps  seen on some model plating.   Can the plates with bumps be reversed so as to look more realistic with nail dents versus the look of rivets which were never used?  Some manufacturers have gone to laser marks that etch small dents so there are no bumps and look much more realistic.

Allan

 

Edited August 22, 2023 by allanyed

[James H]

For my Indy, I wiped down the hull with ethanol to remove any grease and then used 0000 steel wool to polish to a shine.

 

Then I applied a matt varnish with turns it slightly pinky orange in colour.