Hot tips for cold cookin' New information about black patina on aluminum plates for the DASSART™ pigment transfer process

This Slate story is about new discoveries concerning "cold cooking" aluminum plates for the DASSART™ transfer process.

Artist and inventor, Bonny Lhotka, has outlined how to generate natural black patina by cooking aluminum in her books, "The Last Layer" and "Hacking the Digital Print ".

Artist and inventor, Bonny Lhotka teaching in her Boulder, Co. Studio.

Christine Ellinghausen ,DASSologist, shows aluminum plates prepared with the new cold cook process in her Florida studio.

These new techniques will allow artists to create much larger aluminum plates without the need for boiling hot water. The cold cook techniques depend on an extended time while being submerged in a solution above 75 degrees . Copper plates will also be affected by this technique .

This aluminum plate, blackened by the reactive patina process, is a background for a DASSART™ archival pigment transfer. This "modern tintype" look compliments the digital image.

The patinaized plates originally outlined in Lhotkas' books are created in a hot water bath of 150F degrees, with the addition of Cascade Complete , additional chemicals and found objects which then leave a deposit of black creating a "ghost image" on the aluminum.

Hot cooked aluminum plates
Found objects and mixed metals will leave ghost images on aluminum plates when in a Cascade Complete saturated bath.
Studio artists use turkey cookers to produce 18 quarts of hot water needed to initiate the black patina reactions. Although this is the fastest technique, the cold cook process will also produce black on the aluminum plates .
These steel drops will effect the color and speed of the caustic bath.
In 150F degree water for 7-14 minuets, aluminum flashing plates become very black as the steel objects promote oxidation colors on aluminum rather than acting as a resist.
Modern tintype on lightly cooked aluminum plate, archival pigment transfer,©Christine Ellinghausen.

Now our research shows that the effects can be accomplished in a warm tap water when specific mixed metals are included in the Cascade Complete bath . The reaction of the metals to each other initiates a deposit of black on the aluminum. This deposition is a natural patina , unlike applied acids.

"The aluminum plate has become completely black due to the reaction of stainless steel and copper in the Cascape Complete and the water hardening chemical cold cook bath," Bonny Lhotka.
"Water hardening chemicals promote this reaction , especially if your local water supply is soft," B.L.

These reactions can be accomplished by the use of mixed metals: stainless steel, copper and steel within the Cascade Complete solution in a naturally hard water bath.

Hard water and reactive metals promote what would be a negative result of black oxidation in commercial manufacturing. Lhotka uses this diposition on the aluminum as an abstract background for the "Modern Tintype" technique outline in her books.

Mixed metals and aluminum plates weighted and submerged in Cascade Complete in 2 gallons of hot tap water, sitting in stainless steel photo pan will deposit black in 2-3 days.

These effects are permanent and plates subjected to these chemical treatments can not be recooked without additional preparation, as the aluminum itself becomes altered on a molecular level. The surface can be sanded to remove the diposition but water or solvents will not effect the oxidation patterns.

37x27" stainless steel darkroom pan . The 24x24 plates, found objects and mixed metals are submerged in Cascade Complete solution. Plexiglass sheets cover the pan to block evaporation.
Plates being prepared for the alternative cold cooking. Latex house paint is thickly applied as a mask on the clean aluminum plates.
Resulting plate
This 24x24 plate has been masked and found objects arranged to resist the deposition in a cold cook bath.
Resulting plate. You can see the brush marks left by the latex paint mask.
Ghost images on cold cooked 24x24 aluminum plate

This plate shows the reactive deposition after 2.5 days in the outdoor bath. During that time the bath went up to 127F degrees due to the sun heating the large stainless steel darkroom pan which was covered with 2 layers of plexiglass to retain the heat and retard evaporation.

Additional water hardening chemicals will promote and speed the diposition of black. These particular plates were not produced with additional chemicals as a medium tone was preferred for the later application of the archival pigment transfers with DASSART™ Premium transfer film.

Cold cooked 16 gage aluminum custom frame, 20x20". Three days submerged in patina solution. Cestudio. 6/16. 1/1.

Extra large plates can now be make in your own studios for impressive installations and projects. The container will have to be invented by artists for their specific needs.

Copper sheet will also develope a patina after extended stay in the Cascade Complete bath, you can see ghost images from aluminum grill topper on one sheet. These deposits are not as predictable as with aluminum.But the cold cook system will add dark patina if the plates are cleaned with a Cascade and household scouring powder paste .Laquered plates will not oxidize...
This plate was in cold cook baths .

A "sand box" shape constructed out of 2"x6" wood , lined with several layers of heavy black plastic will be my next project for 40x40 plates. Clear plastic will be the cover to deter evaporation. I'll build this in a full sun area ,on a concrete patio .

Cold cooked ghost image of gear, Lhotka Studio.
Precipitated calcium carbonate and Purell hand sanitizer will buff out a "sweet spot" for positioning portraits when sanding and/or harsh chemicals can not be used with young students or in public demonstrations...

Below is an informative article on the nature of corrosion and mixed metals which clarified the cold cooking idea. It explains the reaction of mixed metals and solutions in industrial use.

These new cold cooking processes will be included at the DASSART™ workshop, July 8-10, 2016, Milagro Art Center, Prescott, Az.

Christine Ellinghausen , Modern Tintype workshop teaching the DASSART™ transfer systems, Lake Worth, Florida.
©Christine Ellinghausen

Mix It Up Workshops: DASSART™ transfer techniques and mixed media, contact : Christine Ellinghausen,

DASSART™ products and Bonny Pierce Lhotka books are available at DASSART. com. and at Freestyle Photgraphic Supplies,

Got to love this book! I have made index tabs at the chapters...

Below are 2 other stories on the DASSART ™ systems

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