How to Flatten a Bottle Cap
Previously, I showed how I prep my bottle caps when using them as cabochons. These instructions are available as a tutorial in my shop mainly as a jumping place for those wanting to use them for bead work. I get a lot of questions on flattening bottle caps. Those cabochons just look so perfect, but they are not the same effect others are attempting to achieve. They either want those pretty caps you get by flattening unused caps or they are trying to get them as flat as possible.
If you've wondered whether a die cut press is a good investment for flattening your caps, this post may help.
This is my die cut press. I bought it used for $10 and it came without any dies but it is a workhorse. I imagine you'll achieve the same results with a Sizzix (the home version of a die cut press). I'll borrow a friend's old Sizzix and report back if it behaves differently. If you don't have a die cut press, you should use a rubber mallet and a wood block. Don't use a regular ball peen hammer, you'll sacrifice quality for speed.
These shots show what happens to an used bottle cap if you try to flatten it completely flat with a hammer or in the press. The fluted edge turns under and the top caves inward. I can get it pretty flat before it starts to distort (the cap on the right). Then I have to use pliers to finish the turned under edge (the cap on the left). At this point, I could continue to flatten it with either a rubber mallet or the press but the edge will tend to distort, there's just too much metal in that turned under edge for you to get it completely flat. This look is for those who need to hide the edge or want a smooth looking finish. This was actually the jumping block that led to my cabochons. Through trial and error I found I did not have to flatten this far and achieved a much nicer look for beadwork when I stopped before the edge turned under.
But were not talking about cabochons, we want a flat cap. To achieve that, we'll need to prep the sides first. If you have my tutorial or read the parts I had published briefly in my blog, you'll know that unused and used caps behave differently. You want to prep your cap to return it as much as possible to it's unused state.
Using a pair of narrow flat nose pliers (these are Wubbers and I LOVE them), grip the bottle cap just where the indentation is in the side of the cap and gently bend upward. Do not bend to much at once. Go around the whole cap and come back and bend some more if needed. Keep inside the indentations if possible for a uniform look.
This show shows the finished cap next to one that has not been done. You're not trying to flute the edge all the way, just enough to give the press or the mallet something to hit and to keep it from turning under. If you have an unused cap handy, use it for reference.
The orange cap was flattened with a hammer while the blue one was flattened in the die cut press. There is virtually no difference between the two techniques. The orange cap caved in a bit more and the edge fluted downward more, but these could easily have been controlled. The die cut machine does help with that control but only slightly.
These caps are now flattened about the same depth as the caps sold on the market for scrapbook and collage work. The liners can be removed and they would be ready for artwork.
For those wanting them flatter, I whacked away with the hammer and added another layer to the die cut press. This was where I saw a difference between the two.
The camera doesn't show the difference well, but the orange cap was flattened with the rubber mallet. I struck it several times but could not get it to flatten further. I suspect that I would have to resort to a metal hammer along the inner ridge (right at the blue line on the cap). Anytime you strike metal with metal you are going to scrap off some paint from the cap. If the image is important to you, you need to avoid that if possible. I may be able to switch to my small rubber mallet (it's head is about an inch wide) and just hammer that inner line, but that's a lot of effort. The blue cap was done in the die cut press. It is as flat as it will ever be and it took one pull of the handle. The cap is also relatively unscathed.
Further refinement is possible by hammering the remaining ridges and I'll explore that in another post. I'm not sure if you can get a cap completely flat, but I'll give it a try. Removing the lining will make a difference, but that too can be a time consuming task.
If you work with caps, are doing a lot of them, and need them as flat as possible, you should invest in a press of some sort. The old fashioned sizzix die press can be found for about $20 on ebay and probably cheaper at a garage sale. If you're trying to achieve the look of the unused caps for collage work, a rubber mallet and a pair of good flat nose pliers will do the work just as well as the press. Only invest if you do a lot of caps or do them late at night and want to avoid waking up the spouse or kids.