Copper foil (Tiffany Process) is an amazing process and art form with glass. It allows you to create endless projects that is only limited by your imagination!! It is by far my favourite, and I never stop researching to find new techniques and styles.

It is important to understand the difference between copper foil and leadlight processes.

Traditional Leadlight is held together with lead came which is shaped like an “I” beam and then a cement putty is used for strength and weather proofing.

The Tiffany Process uses copper foil to join glass pieces together creating its own “I” beam.

The solder seeps between the pieces and when enough solder is added to the front and back, it makes a shape that secures the glass in place (the “i” beam) this is what the solder is meant to achieve when a stained glass piece is fully soldered.

The final width of a seam (with proper fitting pieces of glass,) is determined not by how much solder you use, but how wide the foil is and how much extends to the front and back surface of the glass.

Should the solder be too thin, there is no structure because it is essentially a metal piece of tape. Building up the solder is what adds stability to the foil.

Solder follows the foil so uneven gaps as well as uneven foiling can result in untidy soldering seams. It can be a little disheartening especially when first starting out.

So here are the ways to nail your copper foiling techniques once and for all!!

Choosing Your Foil

There are many different widths of foil, this is about personal preference. The things to consider are:

  • The look you are wanting to achieve – do you need thin even lines, is it a more organic piece, do you want different size lines and textures- you can use different widths in the same project if this is your thing
  • Choose correct width of foil – There are many different widths of foil, this is about personal preference, the look you are wanting to achieve as well as glass widths – textured glass always varies in width so ensure you take this into account, you need to consider this to ensure that enough of the foil wraps around evenly on both sides to create a stable piece. You can use different widths in the same project if this is your thing. You can use a larger size foil then remove excess with a scalpel if your need to after it is foiled.
  • Foil backing colour – Foil comes in 3 different backing colours.
    1. Copper backed – which is generally the cheapest,
    2. Black backed – this is the most popular and said to have the strongest adhesive.
    3. Silver backed – most expensive and I have never used it.
  • Foil sizes – this is personal choice. Sizing is in inches generally, but I will also add mm, so it makes it easier.
    1. 3/16 “= 5mm
    2. 7/32” = 5.5mm – this is my choice most of the time
    3. ¼” = 6mm – I use this if I have heavy textures
    4. 5/16” = 8mm
    5. ½” = 13mm

Note: 7/32 in is a common size for beginners because it’s easier to centre on the glass. You can use wider foil to add depth or trim it after application for special effects.

  • What glass type you are using –
    1. Transparent Glass – you can see the colour of the foil through the glass, especially if you have not centred it perfectly, which let’s face it no one is perfect right. For transparent glass I would always recommend black backed even when you are not going to patina your piece as it just looks like a shadow and is mostly invisible to the eye. There is nothing more annoying than finishing your piece and there are peeps of noticeable backing showing through your beautiful glass, this is the reason I rarely use anything other than black backed foil.
    2. Opaque Glass- As you can not see through this glass it does not matter what colour backing you use. If you have copper backed, then certainly use it as it will not show.
  • Foil Quality – A good quality foil will be flexible enough that it can form around all the different shapes that fit together to create your finished piece. In order to be able to fit around each individual piece, the foil will need to be stretchy enough that it won’t tear or split when forming to inside curves. Also take into consideration the softness of the foil, as the softness will factor into how well it stretches. Finally, a good quality copper foil will be strong and adhere to the glass well, so that it can be burnished (rubbed smooth) and remove all kinks without ripping or tearing. Foil is measured in mils, with 1 mil being the thinnest. Cheaper foil may tear more easily, especially around curves.
  • Foil Manufactures – I feel now that tape manufacturers have been changing and more and more Chinese brands are coming on the market. It is of the upmost importance to test which supplier you prefer. I have tried many varieties and am still to find a tape as good as 3M Ventura tape which is still by far my favourite and was the best quality on the market as far as I’m concerned, unfortunately they have stopped making copper foil tape… so if you ever come across any it is a good idea to grab it if it is still in the packet and looks to be in good condition. I have had 3M tape for several years that I still am able to use and is still better than others I have tried even though it is old. EDCO would be my second choice as it has good adhesive and good strength. Again, this is personal choice. Avoid cheap foil from Ebay as they are thin and the adhesive is average, but by all means do some testing and let me know if you find any you love….

Grind Your Edges

  • Copper foil tape won’t stick to edges that aren’t ground.

Applying Your Foil

  • Keep the foil centred on the glass edge as you foil each piece.
  • Avoid touching the adhesive side, oils and dirt on your fingers will impact the “stickiness” of the tape. If you have touched it several times when starting, cut it off and start with a fresh piece.
  • Overlap the foil – when you reach the starting point, overlap the foil about 1 cm.
  • Fold foil on the corners like you’re making a bed or wrapping a pressie, be careful to fold the right way as sometimes the adhesive can show, and the solder won’t stick to it. You can easily use your nails or a sharp/pointed tool to flip it the correct way if you notice it.
  • Use your fingers to make sure the foil is squished nicely and overlaps on both sides.
  • Burnish the edge of the glass first then both sides. This is the one of the most important steps as it ensures the foil is free from wrinkles as well as correctly adhered to the glass. Remember foil is thin – about 1 – 1.5mm thick so it is important to remember that it is still quite fragile so you don’t need to rub like you’re trying to remove a stain, as you can tear it accidently!!!
  • Touch up the edges: You can use a scalpel to cut away any excess foil and tidy up the corners. Foil is very easy to cut through, use the tip of your tool to remove the unwanted foil as it is easier.
  • Use black backed copper foil – Some say black backed copper foil has the strongest grip to glass.
  • Use the right size foil: For most stained glass projects, 3/16 in or 1/4 in copper foil is appropriate. Wider foil can make the project look heavy.

Now you should be ready to prepare for soldering!!!!