aaaaarrrrggghhhhh!!!!!!

[lwalden]

Trying to figure out where it all went wrong..... I'm planning on putting together a segmented blank for an Imperial kit and wanted to have a better idea of how it might look before starting, so tried to do a sierra in the same style using cut-offs from a malachite tru-stone pen and a Casein pen. You can see in the picture below the direction I'm trying to get- however you can also see how the casein section ended up being discolored, almost having a "toasted" look. The Casein Jr Emperor I made from which (whence?) this cut-off came did not exhibit any of the discoloration- and while I'm not sure, I think there may have been a little similar discoloration to the ejecta while drilling this blank, which I did on the lathe. When I drilled the blanks for the Jr Emperor, I'm sure they came out the same ivory color as the finished product, with no discoloration. I'm sure I was drilling at a higher speed on the lathe than I was on the Drill Press, and so am wondering if this may be from heat build up. Ed suggested another possibility may be that the casein (being porous) picked up contaminates during sanding, possibly from the aluminum strips- which could also account for why I didn't have any issues with the Jr Emperor, since it was single material blanks. At any rate, thought I'd see if there was anyone else wanting to suggest a cause for this effect, or if anyone else had experienced anything similar while working with casein? I'd hate to end up with the same effect on Imperial blanks if I/we can figure out what happened and what I can do to avoid a repeat.

 

[ed4copies]

Just to be clear, Lyle asked me for my opinion BEFORE posting this.

I suggested he ask the forum, in addition to giving him my comments.

Lotsa heads are better than just MINE.

Have any of the other "casein users" had a similar color transformation???

Thanks in advance for all feedback!!!

 

[WoodNutOntario]

Lyle i have no idea what happened...

But for what it is worth i like the look of what you posted!!:biggrin:

The smoky streaks look very nice to me!

If i had to give some opinion it would be overheating or contamination while sanding.
Basically what Ed said.
I have noticed if slightly too much heat is applied when i am doing an Osage blank it darkens really quickly.

Andrew

 

[maxwell_smart007]

I'm in agreement with the other Andrew!

I don't know what you did, but I like the toasted look - especially when it's variegated like that, and not uniform!

 

[maxwell_smart007]

Isn't casein a protein-based material?

If so, it could be that the heat caused a Maillard reaction (essentially what happens when you brown meat on a grill) - in which heating proteins causes a browning effect.

Aside: (I learned about Maillard reactions by watching Good Eats on the food network - highly recommended!)

 

[RDH79]

I would have thought the aluminum contamination would be a blacker color. That looks burnt like heat build up during sanding, drilling or turning . Is it turned to finish size? if not wet sand with cold water with light pressure and see if it sands out or it just keeps going deeper in the blank.

 

[ed4copies]

As I have said before, Maxwell, you're pretty SMART!!! (infrequently)

 

[ed4copies]

I would have thought the aluminum contamination would be a blacker color. That looks burnt like heat build up during sanding, drilling or turning . Is it turned to finish size? if not wet sand with cold water with light pressure and see if it sands out or it just keeps going deeper in the blank.

Also as I hear the feedback, it occurs to me that there is aluminum on both ends of the casein. IF this were the problem, it should come from both ends, not just ONE>

 

[lwalden]

I would have thought the aluminum contamination would be a blacker color. That looks burnt like heat build up during sanding, drilling or turning . Is it turned to finish size? if not wet sand with cold water with light pressure and see if it sands out or it just keeps going deeper in the blank.

yes, it is turned to finish size and I was wet-sanding to get it there, and it did seem to spread, or deepen, as I got closer to the finished size.

 

[OKLAHOMAN]

I'm betting on drilling. You said you drilled this on on the lathe and that the ejecta(fancy way of saying shavings) may of had a simular discoloration and on the lathe you may have drilled at a higher rate of speed. I've done a few casein pens and have drilled them all on my DP at 250 rpm and no problems. If it was from the aluminum I agree it would be grey not toast colored.

 

[VisExp]

I haven't worked with caesin, but I've segmented a fair amount of alt. ivory with aluminum. That doesn't look like the aluminum contamination that you get from sanding. Aluminum contamination is darker and is pretty obvious as metal. It also streaks, not a consistent pattern like that. I would guess that it would be heat from drilling.

One other thought is what sort of glue did you glue the tubes in with? What has Roy used in the past? Maybe it is some sort of chemical reaction with the glue.

 

[mbroberg]

I have drilled casein on the lathe before without getting the discoloration that you got. I drill all of my blanks at about 750 RPM.

(Once my new lathe arrives I can slow down to about 250 RPM :biggrin

 

[lwalden]

I haven't worked with caesin, but I've segmented a fair amount of alt. ivory with aluminum. That doesn't look like the aluminum contamination that you get from sanding. Aluminum contamination is darker and is pretty obvious as metal. It also streaks, not a consistent pattern like that. I would guess that it would be heat from drilling.

One other thought is what sort of glue did you glue the tubes in with? What has Roy used in the past? Maybe it is some sort of chemical reaction with the glue.

For glue, I used medium CA- same as on the Casein Jr Emperor that did not discolor. OK, just went out and actually checked my Jet VS mini to see what the low speed is when it's adjusted all the way down.... on the upper of the three possible belt settings.... 1700 rpm may have been a tad fast. At this point I'm pretty sure it was my poor choice of not taking the time to step down the belt/pulley combo from my normal turning speed, resulting in excess heat buildup, that caused the discoloration. :redface:

 

[BRobbins629]

My casein did not discolor. Although I hate to recommend vendors other than my good friends at exotics, there is another very similar looking material around that is celluloid. It too has a few issues but generally is very easy to turn and I don't think would darken. You do have to be careful of getting it too hot and be careful with the shavings but it can easily be mistaken for casein in looks. Material is available from American Art Plastics.