Thursday, 14 November 2013

EMBOSSING AND PHOTO ETCHING INDUCTION

Examples of embossing and debossing:

Plates can be made from card, wood, copper plates, plastic and mount board (wood mdf). Choosing the thickest stock for the plate is not necessarily always a better option.

There are two types of embossing, one raises the paper and the other indents the paper (debossing). Metal copper plates are the best option for debossing.



An example of a copper plate used to deboss.





The above example has been embossed using a copper plate.

Above are further examples of embossing and debossing using various different plates (made out of different stock).

Examples of copper plate embossing and debossing:

Using copper plates to emboss requires a process called etching. 

This is where, a varnish is placed on a metal plate and eroded away.  




The copper plate above shows the finished product of both embossing and debossing through etching.


Down and out - acid on the copper plate when preparing for type based work, can cause parts of the letters to erode, such as the counters on the 'e' and 'g', as shown on the image above.

The way to avoid this is to constantly watch the plate when being prepared, or using a sans serif font, with a point size of at least 10.

Summary:

For embossing it is best to use a 2 or 3mm piece of mdf and laser cut the letters for a clear, crisp outcome. 

When using copper to deboss or emboss it can be a costly and time consuming process.

Some papers work well under different pressures, whilst others don't so it is important to experiment before making a final decision. 

The positive image needs to be printed onto frosted film, not paper. It shouldn't contain any half tone imagery or text when embossing.

When embossing business cards it is important to lay them out in a grid format as shown above, as this is a sustainable way of producing multiple cards/prints at once.

For inked embossing use a rubber roller and ink like a link cut would be printed to ensure the ink doesn't leak into the plate detail. It is also possible to print/screen print an image/type and then emboss or deboss it using etching.

Preparing a copper plate for photo etching:

When preparing a copper plate, it is important to sand the copper plate down on one side where the etching will be made. This is to ensure no marks or increments are on the plate. 





Rinse the copper plate with water, and then with degreaser, to ensure the plate is smooth and clean, to avoid any interference with the acid used in the etching process.




Dry off with newsprint.


Lay frosted film under the plate on the printing roller bed.



Peel the back of the light sensitive film and carefully place over the copper plate. Check for no bubbles or wrinkles as this can cause an anchor point to strain the film. 




Pressed and prepared plate.


Cut off excess around the copper plate.


When exposing the screen it is best to use 8-10 light units. Place the positive ink side down, with the lettering reversed. uUse tape to hold down the plate, and again trim off any excess. 

For photo etching half tone is too coarse. Use Rachelon dot screen whilst exposing the plate to allow random dots to be added to the photo adding tone and depth. Each RDS is worth approx $500 each.

After the exposure remove the clear layer of the light sensitive film, and place in the prepared solution shown below.


To prepare the solution use approximately 10g of sodium carbonate with 1 litre of water. Use hot water initially to dilute and top up to the 1L point with cold. Should be 18degrees. It is best to do this 3 times producing 3L of the sodium carbonate solution. This levels out the solidity and temperature. 




For normal photo etching leave in the solution for 2 minutes, and for embossing wait up to 10 minutes. Rub this with a sponge every 30 seconds. It isn't bad to over develop. Wait until the copper plate is clear, with no dots, then rinse with cold water and dry again with newsprint as shown before in order to cause no damage to the copper plate.




Place a hook on the back of the copper plate using tape, and attach to a piece of paper. 



Place in the acid and leave for up to 7 hours. 

It etches quicker at the bottom, the liquid collects and slides down the plate, etching half quicker than the other. This is why it is important to turn the plate around at even intervals throughout this final process.



How to use the copper plate to emboss:


Place on a wooden board and cover with chosen stock, and newsprint.


Place inside the hydraulic nipping press and set up as directed - tighten screws, ensure black button is outwards. Pump the handle until it won't go any further, then push the B-Button and keep pumping. 

The higher the pressure, the cleaner the emboss with be. It will reach around 350 bar. 

Then unlighted the screw to release the pressure.





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