Newspaper Hemispheres

[BJV]

This is how I make my Newspaper Hemispheres:

 

1. http://barry.dcwisp.net/np2.jpg

I fill a plastic 5" hemisphere with casting resin,

after I insert a piece plastic pipe in the empty

hemisphere. Coat the hemisphere with mold release.

 

2.

This what the mold should look like.

http://barry.dcwisp.net/ph2.jpg

3.

You have to cut a paper template and cut

the newspaper like the photo.

http://barry.dcwisp.net/np1.jpg

4.

Wrap the mold with plastic wrap as shown.

http://barry.dcwisp.net/ph4.jpg

5.

I then paste 12 layers of newsprint

for a 6" and 10 layers for a 5"

http://barry.dcwisp.net/ph5.jpg

6.

I then cover the newsprint with aluminum foil

and smooth it with a block of wood. Remove the foil after smoothing.

http://barry.dcwisp.net/ph6.jpg

7.

Let the newspaper dry for several hours or over night.

The cut the newspaper even with the bottom

of the mold. And remove from mold.

http://barry.dcwisp.net/ph7.jpg

8.

After you make one more they should look like

this.

http://barry.dcwisp.net/ph8.jpg

BJV

Edited January 16, 2011 by BJV

[NightHawkInLight]

Thanks for the tutorial, it's always good to see a quality building method demonstrated. Those look excellent. I'm considering making a few dummy resin filled shells for a hands on display, is that brand of resin normally that foggy, or is that a result of something you have done to it?

[BJV]

Thanks for the tutorial, it's always good to see a quality building method demonstrated. Those look excellent. I'm considering making a few dummy resin filled shells for a hands on display, is that brand of resin normally that foggy, or is that a result of something you have done to it?

 

I think the foggy look comes for me sanding them with 220 sandpaper.

BJV

[NightHawkInLight]

It seems that one is clear and the other is a dirty yellow, why is that?

[BJV]

It seems that one is clear and the other is a dirty yellow, why is that?

 

I bought the casting resin from two different places, two different brands.

BJV

[dagabu]

I just love it when a simple but completely useful tool is created and then shared with us. You really hit the mark on that one BJV!

 

Thank you!

[NightHawkInLight]

I just love it when a simple but completely useful tool is created and then shared with us. You really hit the mark on that one BJV!

 

Thank you!

Agreed 100%. I envied your hemi's whenever I have seen your build pictures.

 

What this makes me curious about is creating a negative mold and using both to press hemi's out of paper mache using really fine paper pulp. It would be cool for your own use and maybe even for making some cash. It may take a big initial investment to make the molds for 12-16" shells, but if it's quick and cheap to make the hemi's it could pay for itself quick. You could undercut commercial prices by a good deal and still come out making good money for the effort. Mount the molds to a big ol rocket press to get even pressure, if that happens to be required.

 

Edit: Just thinking to myself, if you didn't need to move it around much, a negative for any size shell could be easily and cheaply made from concrete.

Edited January 16, 2011 by NightHawkInLight

[dagabu]

Agreed 100%. I envied your hemi's whenever I have seen your build pictures.

 

What this makes me curious about is creating a negative mold and using both to press hemi's out of paper mache using really fine paper pulp. In fact, a vacuum and a heavy but tight screen would allow for instant shells when dipped into a slurry pulp. It would be cool for your own use and maybe even for making some cash. It may take a big initial investment to make the molds for 12-16" shells, but if it's quick and cheap to make the hemi's it could pay for itself quick. You could undercut commercial prices by a good deal and still come out making good money for the effort. Mount the molds to a big ol rocket press to get even pressure, if that happens to be required.

 

Edit: Just thinking to myself, if you didn't need to move it around much, a negative for any size shell could be easily and cheaply made from concrete. I would use non-shrinking grout, it would be much stronger and smoother.

[patsroom]

Very useful, well done.

The paper shell that you show made using this method is the best home made I have seen.

Thank you for sharing.

[TrueBluePyro]

Yes! That was very well done.

Now what glue do you use when you start laying the newspaper down?

Also would there be something cheaper than using 'casting resin'?

[BJV]

Yes! That was very well done.

Now what glue do you use when you start laying the newspaper down?

Also would there be something cheaper than using 'casting resin'?

 

I use Elmer's white glue to paste the newspaper to the mold.

Also I have not found anything cheaper than casting resin, that works.

BJV

[AdmiralDonSnider]

Great tool. The only thing that looks tedious is the use of special paper cutouts. Wouldn´t there be easier shapes to use, maintaining minimum overlap?

 

In addition, I´m interested in how thick you make your newsprint hemis. I´ve questioned the topic of thickness in another thread on newsprint hemis I opened a while ago. It really seems that their potential is only exploited to the fullest if the hemis are made thinner than their strawboard counterparts.

[davis050594]

Great tool. The only thing that looks tedious is the use of special paper cutouts. Wouldn´t there be easier shapes to use, maintaining minimum overlap?

 

In addition, I´m interested in how thick you make your newsprint hemis. I´ve questioned the topic of thickness in another thread on newsprint hemis I opened a while ago. It really seems that their potential is only exploited to the fullest if the hemis are made thinner than their strawboard counterparts.

 

He said the amount of layers above, "I then paste 12 layers of newsprint

for a 6" and 10 layers for a 5". They are thin

Edited January 17, 2011 by davis050594

[AdmiralDonSnider]

He said the amount of layers above, "I then paste 12 layers of newsprint

for a 6" and 10 layers for a 5". They are thin

 

Oh, sorry, overlooked it. Thanks for pointing it out. Nice hemis! I´ll give them a try soon.

 

Now, as the hemi is thinner, how do you compensate for the loss in container strenght? Do you paste more layers?

Edited January 17, 2011 by AdmiralDonSnider

[BJV]

Oh, sorry, overlooked it. Thanks for pointing it out. Nice hemis! I´ll give them a try soon.

 

Now, as the hemi is thinner, how do you compensate for the loss in container strenght? Do you paste more layers?

 

AdmiralDonSnider

I do not think that the strength of hemi's is very important. All I want the newspaper hemi's to do is just

contain the stars and burst. The weaker the hemi's the better for a good break.

Here is a photo of a couple of fragments of the shell I shot last Friday.

I use 10 layers of 50lb gum tape on the 5" shell and 13 layers on my 6"

BJV

http://barry.dcwisp.net/fragment.jpg

Edited January 18, 2011 by BJV

[TrueBluePyro]

I'm pretty sure the Japanese use newspaper hemispheres.

Also, most people have agreed that thinner hemis are better because most of the strength will come from the pasting and there wont be a weak spot where the two hemis meet.

[AdmiralDonSnider]

I do not think that the strength of hemi's is very important. All I want the newspaper hemi's to do is just

contain the stars and burst. The weaker the hemi's the better for a good break.

 

 

I was told the same by others e.g. John Reilly on rec. pyro, but still was under the impression that the thinner hemi is compensated with more pasting, as it also makes part of the shells wall. Your argumentation sounds plausible, but I wonder why larger strawboard hemis are made thicker if this theory applies.

 

Another thing that comes to my mind is that you can´t just start at the ID of strawboard hemis when making newsprint ones, otherwise the smaller OD together with the same amount of pasting would give a finished shell that is some mm smaller than its strawboard counterpart. I guess you compensate for this by using a former somewhat larger in ID than the ones used for pressing strawboard hemis, right?

 

I'm pretty sure the Japanese use newspaper hemispheres.

Also, most people have agreed that thinner hemis are better because most of the strength will come from the pasting and there wont be a weak spot where the two hemis meet.

 

They do for domestic shells, as Shimizu mentions. The footage on Karlos youtube channel (hajdahanabi) supports this.

Edited January 18, 2011 by AdmiralDonSnider

[BJV]

I was told the same by others e.g. John Reilly on rec. pyro, but still was under the impression that the thinner hemi is compensated with more pasting, as it also makes part of the shells wall. Your argumentation sounds plausible, but I wonder why larger strawboard hemis are made thicker if this theory applies.

 

Another thing that comes to my mind is that you can´t just start at the ID of strawboard hemis when making newsprint ones, otherwise the smaller OD together with the same amount of pasting would give a finished shell that is some mm smaller than its strawboard counterpart. I guess you compensate for this by using a former somewhat larger in ID than the ones used for pressing strawboard hemis, right?

 

 

 

They do for domestic shells, as Shimizu mentions. The footage on Karlos youtube channel (hajdahanabi) supports this.

 

The diameter of my newspaper 6" hemi's is 5 1/2" after adding the 13 layers of 50lb gum tape brings the diameter up

to 5 3/4" which seems to work well for me. Have a look.

BJV

[AdmiralDonSnider]

Interesting, thanks. Your shells are quite sightly; should use less zoom to catch the full bon.

 

For a 5 Gou= 6 Inch shell Shimizu suggests an OD of 135mm and a wall thickness of 3mm, just for comparision.

[BJV]

Interesting, thanks. Your shells are quite sightly; should use less zoom to catch the full bon.

 

For a 5 Gou= 6 Inch shell Shimizu suggests an OD of 135mm and a wall thickness of 3mm, just for comparision.

 

(; should use less zoom to catch the full bon.)

The problem is our shoot site is to small. I can't get back far enough.

This summer we will have a better shoot site and I will be able to videos of the full break.

BJV

[Karlos]

Japanese make newspaper hemispheres for big calibers, but they paste paper strips over wooden ball. After drying, they cut it into two hemis. Time consuming proces, like pasting. Edited January 26, 2011 by Karlos

[AdmiralDonSnider]

Yes. This is described in Shimizu. Just wonder why they do this if layers with mininum overhang are all that is desired. Is it to change grain direction?

[NightHawkInLight]

Yes. This is described in Shimizu. Just wonder why they do this if layers with mininum overhang are all that is desired. Is it to change grain direction?

Changing grain direction with newspaper is pointless. Only in virgin paper is there a true grain, recycled stuff almost never has a substantial difference in tensile strength in any direction. It is likely just what they are setup to do, as it is the same method they use for pasting later.

[AdmiralDonSnider]

Yes, good point. I guess it doesn´t have a detrimental impact on the hemi quality if you use larger cutouts, not strips, to form the layers.

[50AE]

I read the topic and I liked the method. I decided to try it with 4" shells and it is successful. Just made a 4" shell ready for pasting.

I think it's pointless on the 4" though, but practical on the 6" and higher size. For me vacu formed hemis will be the way to go for 4", and 6" maybe.

 

Photos:

 

http://img833.imageshack.us/img833/2656/picture004su.th.jpg

View of the hemis

 

http://img843.imageshack.us/img843/2346/picture005tx.th.jpg

Making a shell

 

http://img607.imageshack.us/img607/6986/picture006r.th.jpg

Shell ready to be pasted

 

http://img199.imageshack.us/img199/6522/picture007ju.th.jpg

The mold - made from plaster of paris covered with shellac.