Paraffin wax mottling
Uncle Al
>
> Hello everyone. There is a phenonmenon in candle making that I
> have been studying for quite some time now. I have observed in certain
> paraffin waxes the appearance of tiny, white, snowflake-like blooms
> (intermingled with coloured dye covering the rest of the background)once
> the wax has cooled to room temperature. Our wax refinery produces quite
> a number of different melt point paraffins and this effect seems to
> occur only with low to medium melt point paraffins. It has been my
> observation that fragrance oil (or even mineral oil) seems to enhance
> the effect although the "mottling" can be seen in the product wax before
> it is melted and poured for candles.
> We know what stops this effect cold in its path: microcrystalline
> wax, polyalpha olefin, and polyethylene will, at low concentrations
> (0.5-1%), completely eliminate the snowflaking to produce a uniform
> surface colour. Under microscope, these additives all serve to create
> much smaller paraffin crystals than normal.
> We also know that the rate of cooling can have a substantial effect
> on whether this mottling will occur or not (slow cooling seems to
> enhance it).
> When comparing gas chromatograms and differential scanning
> calorimetry profiles of a batch of wax that does and doesn't mottle,
> there seems to be no difference at all in carbon distribution and
> transition temperature.
> Under the microscope, we have observed this effect with successfully
> mottling waxes: Once the paraffin crystals have formed (usually in
> needles with a few plates), tiny rippled patterns tend to propagate
> throughout the field of view and tend to resemble dark, fuzzy fractures.
>
> I am at a loss to explain why this effect occurs only in certain
> paraffins, and why the use of high-melt amorphous wax additives and
> certain polymers tend to completely eliminate this phenomenon. I have
> poured through a large volume of paraffin crystallization journal
> articles and no reference is made to this effect.
> Can anyone shed some light on
> this?
>
> Sincerely, N. Marsden
In a highly crystalline matrix micro-defects (dislocations, stacking
faults, whatever) will migrate along grain boundaries and gather to form
cracks. If you add a smidgeon of rubber things are blunted at the
interface and little defects cannot cluster into big ones. (BTW, this
is a scientific wild ass guess for wax.)
It would be interesting to add a percent or less of fumed silica (*very*
small particles and very well dispersed - no settling allowed) to badly
mottling wax and see if the ceramic nanoparticles as immobile defects
themselves pinned mobile matrx defects and prevented their clustering to
mottling. (Don't do this on a ton scale until you play with grams.)
--
Uncle Al Schwartz
http://www.mazepath.com/uncleal/
http://www.ultra.net.au/~wisby/uncleal/
http://www.guyy.demon.co.uk/uncleal/
http://uncleal.within.net/
(Toxic URLs! Unsafe for children and most mammals)
"Quis custodiet ipsos custodes?" The Net!
ed marsden
Uncle Al
[snip]
> I wish it were that simple, of course. What I set out to do was to get this effect
> to occur in a series of various melt point paraffins that we market. It naturally occurs
> post-congealing point with only one or two of our feedstocks and is enhanced in the
> presence of white USP oil or fragrance oil. Getting the other waxes to exhibit this
> snowflaking has been unsuccessful.
Sounds like you get an insoluble parting layer lubricating crystal grain
fracture.
> I am about to take Uncle Al's advice to suspend fumed silica into the cooling cup of
> wax and make notes.
Mix exceedingly vigorously or sonicate to disperse in the molten wax.
Avoid breathing the dust.
> With the present information regarding the relationship between air and
> mottling, I tried casting a mottling wax under high vacuum in an attempt to purge the
> paraffin of gases. The result? A vertically distorted candle with a thin texture
> resembling broken air bubbles and thin patches of white intermingled with the red candle
> background.
Assuming the molten wax was well degassed (stir bar is good, vibromixer
is better) it still sounds like dislocations migrating along grain
boundaries to coalesce into cracks as bulk shrinkage creates internal
tension.
> An important observation was made with a comparison between a mottling wax that had
> been degassed under vacuum and one that hadn't. The degassed paraffin took several hours
> longer to mottle than did the control candle.
Perhaps that means micro air bubbles exsolved during cooling act as
nucleation centers for grain boundary failure (e.g., stress fracturing
and hydrogen embrittlement of metals). If fumed silica also does that,
you should spread the failure throughout the bulk on a micro scale and
avoid macro patches, especially in degassed wax.
> I think I'm in over my head. I'll be posting pictures next!
NO BINARIES IN SCI.CHEM! Post links.
I love intellectual foreplay leading up to the big experiment! Will
fumed silica be a miracle as per spec? Is the physical failure process
unrelated to metal grain boundary analogies?
If massive nano-seeding doesn't do it, next step is instead to add
wetted microfibers to tie the pieces together.
ed marsden
> Since this original posting, I had come across an article from 1926 that briefly spoke of
> an effect similar to what I had described - the white blooming that forms at varying
> degrees both superficially and beneath the surface of the wax. This article claimed that
> shaking wax with air (in a jar I suppose) tended to substantially increase mottling.
I wish it were that simple, of course. What I set out to do was to get this effect
to occur in a series of various melt point paraffins that we market. It naturally occurs
post-congealing point with only one or two of our feedstocks and is enhanced in the
presence of white USP oil or fragrance oil. Getting the other waxes to exhibit this
snowflaking has been unsuccessful.
I am about to take Uncle Al's advice to suspend fumed silica into the cooling cup of
wax and make notes. With the present information regarding the relationship between air and
mottling, I tried casting a mottling wax under high vacuum in an attempt to purge the
paraffin of gases. The result? A vertically distorted candle with a thin texture
resembling broken air bubbles and thin patches of white intermingled with the red candle
background.
An important observation was made with a comparison between a mottling wax that had
been degassed under vacuum and one that hadn't. The degassed paraffin took several hours
longer to mottle than did the control candle.
I think I'm in over my head. I'll be posting pictures next!
NM
>
>
> Uncle Al's silica "nanoparticles" sound like a neat solution to
> what sounds like a common materials problem. You should be able
> to find lots of literature on microstructure and the effects
> of various influences on crystalization during solidification
> of alloys/mixtures. It is very dependent on the material, and
> the cooling path. I'm fascinated by the wide varieties in
> microstructure, and corresponding properties of steel & aluminum.
> --
> Hugh Lippincott hu...@an.hp.com
> I speak for myself not for HP
Jeff
company and we hove some experience with it. We actually sell mottlers for
wax but I would also like to understand it more. There is also a blend of
wax which has recently come to market in candles that is heavily
crystallized. The crystal needles completely cover the surface of the
candle. I am trying to figure out how this effect is accomplished. I would
be interested in any information you discover in your experiments and would
be happy to share any I find in mine.
Jeff
ed marsden <ed.ma...@utoronto.ca> wrote in message
news:3782E569...@utoronto.ca...
ed marsden
the candle surface showed large needle-like crystals constituting a rough
texture. Analysis showed that the entire candle had been cast from stearic acid.
We didn't get a chance to burn it but it had quite extraordinary surface
features. I haven't seen them in stores ; only those damn mottling candles!
Keep in touch, I'm hoping to find a solution to our mottling problem in the near
future.
-N. Marsden
iva.gy...@gmail.com
http://sonomechanics.com/applications/liquid_degassing/
https://www.youtube.com/watch?v=fNo_L_xHKU4
https://www.youtube.com/watch?v=23nsW2yAl_o
Unlike vacuum degassing, which is a batch approach, ultrasonic degassing can be done in a continuous-flow mode.
On Friday, July 2, 1999 at 3:00:00 AM UTC-4, Uncle Al wrote:
> faults, whatever) will migrate along grain boundaries and gather to form
> cracks. If you add a smidgeon of rubber things are blunted at the
> interface and little defects cannot cluster into big ones. (BTW, this
> is a scientific wild ass guess for wax.)
>
> It would be interesting to add a percent or less of fumed silica (*very*
> small particles and very well dispersed - no settling allowed) to badly
> mottling wax and see if the ceramic nanoparticles as immobile defects
> themselves pinned mobile matrx defects and prevented their clustering to
> mottling. (Don't do this on a ton scale until you play with grams.)
>
>