a magnifying glass out of resin?

[Galemys]

Just curious, (and living in a resin-less part of Holland);

would it be possible to turn a lump of clear resin into a magnifying lens, of a quality good enough for firelighting?
Shaping the sphere could (well, in theory ) be done by either sanding & polishing or melting & moulding (& off course polishing).

Your thoughts please,

Tom

 

[British Red]

I have absolutely no idea....I have heard of the idea of carving a lens from ice...and heard others say you get a cold wet hand.....I like the resin idea...if anyone can find me a big enough lump I'd love to try it and publish some pictures!

Red

 

[Ahjno]

Good one Tom

First thought would be it isn't suitable, as it isn't 'pure' / clear enough: it would difuse the sun's rays and thus not creating a good focus.



Vikings used to use rock chrystal lenses: http://en.wikipedia.org/wiki/Burning-glass

 

[Toddy]

And if you heat it up it melts and goes sticky

Cheers,
Toddy.....who's been making medieval scented beads using resin, etc....it's a b*gger to get out of the coffee grinder, sticks like varnish

 

[OldJimbo]

Back in the old days we would mount larger specimens in hollowed slides for microscope work and fill the rest of the hollow with Canada Balsam - the resin out of balsam fir trees. It sets clear and has same refractive index as glass. So It would be theoretically possible given a mold and some basam resin. Other resins are sticky even when set and aren't clear.
I've got a pic up in the firecraft section showing popping balsam blisters to use with lichen for tinder. Messy business! Resin from leaves and other parts of tree turns everything black and is really messy.

 

[DOC-CANADA]

I have heard of the idea of carving a lens from ice...and heard others say you get a cold wet hand.....
Red

Thought you might be interested in this link.
http://www.wildwoodsurvival.com/survival/fire/ice/index.html

Cheers!

 

[BobFromHolland]

Thought you might be interested in this link.
http://www.wildwoodsurvival.com/survival/fire/ice/index.html

Cheers!

DOC-CANADA, that link sure has some clever tips on the subject of fire-by-ice!

Great pics as well.

I guess i'll just have to wait an other 8 - 9 months 'till I can have a go at it.

Bob

 

[British Red]

Fantastic stuff.....Cheers DOC...you just kniow I'm going to have to try this dont you?

Red

 

[match]

And if you heat it up it melts and goes sticky

Cheers,
Toddy.....who's been making medieval scented beads using resin, etc....it's a b*gger to get out of the coffee grinder, sticks like varnish

Toddy - if you mix a little finely ground charcoal in with the resin while its melted, it forms a glassy black non-sticky when it dries (same technique as is used in making pitch as a glue). This can be more easily shaped and rolled into beads, still carrying the scent but not anywhere near as sticky to work with or wear

 

[Toddy]

I was trying a medieval recipe and it stays a deep pink colour from ground rose petals, but I am so tempted to try the charcoal. Thanks Match.

Cheers,
Toddy

 

[Grooveski]

The pigment in cherry resin would rob all the light wouldn't it?

It's pretty clear and the dry stuff can be polished to the extent of making a lens. The surface goes white just like stone but wet it and whammo, it's really quite clear indeed.
I've seen resin so light in pigment that it's more yellow but all I have here is the usual amber.

Canada Balsam sounds like a trip to the botanic gardens. I don't know one fir from another but can't recall ever seeing clear resin.
That would be the way to do it though. Big dod of clear resin, dry it and if it's anything like cherry then grinding and polishing it would be a joy compared to a rock crystal pebble.

 

[Seagull]

I recall that Canadian Balsam was used by nautical instrument makers, to join bits of prism , as in Bino,s.

Trouble was, the alignment had to be exact, the first try, there was no second chance. So, repairs were a bit chancy.


But I dunno if the stuff would mould.

Ceeg

 

[Galemys]

Thanx for the feedback guys (& galls)

Tom

 

[Toddy]

I've got some chunks of purified gum arabic in crystal form. Theoretically if it's dissolve in hot water and then cast and allowed to dry it might make a lens....no idea whether it would work though.
Cheers,
Toddy