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Step 4Pasting the shell
The next step is pasting the shell, which is the hardest and most time-consuming part of round shells. The pasting method descriped here is the socalled 3-strip pasting method. Unlike the "normal" pasting method (pasting strips with a length of half the equator around the shell) the 3-strip pasting method does not "build up" near poles.
To make your pasting strips sticky before you paste you will need to add a glue to each 70x15 mm kraft paper strip on one side. This can be done quickly by arranging some strips on a wide wooden board. Next apply a thin, even layer of wheat paste with a brush. These strips are now ready for pasting, but you will need to repeat this step many times, since you will need a lot of strips to complete your shell.
The shell is pasted as showed on the picture. A strip is pasted from the "northpole" pointing towards the "southpole". Then a strip beside is pasted from the "southpole" pointing towards the "northpole". A strip is then pasted between these two strip. This pattern is continuously pasted around the shell. Press out the airbubbles under the strips, this will result in a nice-looking shell. Everytime you finish a way around the shell (layer) make sure to write on the shell how many layers you have pasted so far, you might forget it. When finished pasting the shell, multiply the layer-number by two, since each layer with this pasting method counts for two actual layers.
While pasting the shell, cut a ~8 cm piece of cotton twine and make a loop on it. Hot glue it to the top of the shell (the opposite hemispheres of the one with the time fuse in it) and paste like before, just making the strip covering the twine. This shell needed 10 layers of pasting (=20 layers) to complete. The ideal is to make the shell ~5 mm smaller than the mortar tube, in this case the OD of the shell should be ~7 cm. Making it this diameter might take hours for beginners to complete. After the layers of pasting, let the shell dry completely.
To make your pasting strips sticky before you paste you will need to add a glue to each 70x15 mm kraft paper strip on one side. This can be done quickly by arranging some strips on a wide wooden board. Next apply a thin, even layer of wheat paste with a brush. These strips are now ready for pasting, but you will need to repeat this step many times, since you will need a lot of strips to complete your shell.
The shell is pasted as showed on the picture. A strip is pasted from the "northpole" pointing towards the "southpole". Then a strip beside is pasted from the "southpole" pointing towards the "northpole". A strip is then pasted between these two strip. This pattern is continuously pasted around the shell. Press out the airbubbles under the strips, this will result in a nice-looking shell. Everytime you finish a way around the shell (layer) make sure to write on the shell how many layers you have pasted so far, you might forget it. When finished pasting the shell, multiply the layer-number by two, since each layer with this pasting method counts for two actual layers.
While pasting the shell, cut a ~8 cm piece of cotton twine and make a loop on it. Hot glue it to the top of the shell (the opposite hemispheres of the one with the time fuse in it) and paste like before, just making the strip covering the twine. This shell needed 10 layers of pasting (=20 layers) to complete. The ideal is to make the shell ~5 mm smaller than the mortar tube, in this case the OD of the shell should be ~7 cm. Making it this diameter might take hours for beginners to complete. After the layers of pasting, let the shell dry completely.
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Feb 5, 2009. 5:25 PMReplicator
says:
Why paste it at all? What's wrong with just gluing it together? I'm sure you have a reason, I'm just curious.
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Feb 18, 2009. 9:50 AM
pudi.dk (author)
says:
pudi.dk (author)
says:
Gluing (using solvent to dissolve the plastic) together can be done if using plastic hemispheres. However if using paper hemisperes which is more "traditional" gluing together will not develop as much pressure inside the shell and the stars would just spill out instead of creating a sphere. Generally you'll get better breaks with paper hemispheres with pasting rather than using glued plastic hemispheres, but other things as break charge and booster will make a difference.
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