The procedure begins by locating two pieces of Mylar which are at least 1" larger in both dimensions than the item to be encapsulated.

The two pieces of Mylar are aligned flush at the edges and placed on the table of the ultrasonic welder so that about ¾" of it extends beyond the edge. This image shows a close-up of the welder tip. If the piece is rectangular, the first weld should be made along one of the long sides.

Throughout the process, it is a good idea to keep slack out of the Mylar by raking it with the hands, clad with soft cotton gloves.

And this image shows the view down the table's edge, along which line the weld will be made. Also shown is the green magnetic hold-down mat. This is positioned over the work and with its edge just about 1/8" to 1/4" from that of the welder's table (red arrows). The table being made of steel, the mat clamps magnetically to it, holding the Mylar securely in place. The mat somewhat obscured the view of the procedure in later images, so it only appears here. But any time a weld is being made, the mat needs to be in place.

The welder is controlled by a foot pedal. It can be made to move either direction by stepping on either the right (forward) or left (reverse) side of the pedal.

This image shows the welder with the welding head in the beginning location.

And by comparing this image with that of the previous slide, we see the direction the head moves in making a weld.

While it might appear that the maximum size of items that can be encapsulated is limited to the distance of the head's range of travel, it is altogether possible to encapsulate items larger than this. In fact, there is really no maximum size limit. Such oversize items are welded the length of travel, then pulled back (left, in the image) head and all, and another weld is made.

Now we see the weld in progress. The line that looks like a jet stream is the weld.

The first side being welded, the material is now placed between the two pieces of Mylar and butted up to the weld.

The material is situated in the welder so that the weld will begin at the edge bearing the first weld. If the piece is situated so that the second weld ends at the edge with the first weld, there is risk of generating a wave of slack in the Mylar as the welder head makes its way across the width of the work. If that happens, the piece must be removed from the enclosure and the procedure started over with new Mylar. This risk increases proportionately with the size of the item being encapsulated. Of course we have to end our last weld at another weld, and when encapsulaing large items, extra care is taken to avoid ending up with slack at the fourth and final corner. So, once the first weld is made, the rule to remember is:

Every weld begins at the weld that most recently precedes it.

The second side is welded. On to the third and fourth sides.

All four edges are now welded.

Finally, the outer margin of excess Mylar is trimmed to about ¼" to 3/8" outside the welds. I've used the reflection of the Mylar to show about how it should look. The piece is now finished.

One very good feature of this treatment is that it is totally and easily reversible. If ever the piece needs to come out of the Mylar, it's a simple matter of cutting the Mylar along one edge …

… and removing the piece.