Dam Label Casting

[Dorno]

I have had this label casting business (lol)
After finally getting the label part sort of right and casting my blank as I go to turn the dam thing it chips cracks and is ruined.
What I would like to know is it possible to use to much hardener and by doing this will that make my polyester resin blank even more brittle than they usualy are ? If I use less hardener will they take longer to set .

Thanks Ian

[gawdelpus]

Generally more hardener more brittle quicker set time .my first castings only had 2 drops of hardener took 2 days to set lol. Currently I use about 6-8 drops of activater to 25 mills of resin. They gel up in a couple of hours and are hard enough to dmold in about 4-6 hrs, I usually sit my castings on top of my modem as its quite warm overnight, no problems so far and no bubbles I can see ,half blind I am hehe. I have not tried labels but various stickers and of course my printed decals . All of which have been successful so far :)
I don't know if that helps with what you are doing ,but no doubt more advice will follow , cheers ~ John

PS try using top speed and a skew for the acrylics should get a much smoother cut that way ,more shear than drag !!

[dj_pnevans]

What John said to much hardner, when you find what mix you can use stick to it. Keep going you will get there.
David

[MBUMIK]

what they said but i have found even with a brittle blank you can still turn it if you use a very sharp skew

keep trying mate you will get there in the end

i am also having a few casting probs but i wont let them beat me,,,,,,,,YET

have fun with it

MIK

[Dorno]

Thanks fellas I won't let the bastards beat me lol.
david has given me alot of advice to do with all this so I will make it work but I was and still unsure about the hardener side of things better luck with my next couple lol

Cheers Ian

[MBUMIK]

thats the attitude

on the IAP site they talk about 9 drops per ounce and an ounce is around 28mls

i do it by measurement ie. 125mls is 1/4 teaspoon or 1.25mls which is 1%
i don't worry too much on exactness and one day i may even end up with milton the monster but close enough is good enough for me - damn maybe thats what i am doin' wrong

MIK

[NewLondon88]

A couple of things came to mind right away .. one is the hardener. As others have
mentioned, more catalyst can generate heat more quickly so you get a faster cure. But
the tradeoff is a more brittle blank.

Also, the type of resin makes a big difference. Resins from a craft store aren't usually
meant for turning. People use those to pour into a mold and embed items, so a more
brittle resin is no problem for that purpose. But we subject the resins to some rather
harsh punishment with high speeds, cutting tools, hot drill bits, saw blades etc.
Some of the craft type resins are just not meant for this treatment and will crack or
chip out.

I often see people talking about turning blanks in a matter of hours. Keep in mind
that the cure may take several days even though it might be ready to de-mold in hours.
During that time, the resin is still somewhat flexible, so any stresses you put it under
can show up as air pockets around the tubes. You've got a lathe spinning the blank
at 2000 or 3000 RPM.. and a chisel trying to stop it instantly. That can put a lot of
flex in a resin that is set up and firm, but not really cured yet.

ok, that's all the ideas I have for now. :p

[Dorno]

By George I think I or at leaset you all may have solved part of my problem. That part being the amount of hardner used. I am not going to reveal the amount of hardner I have been using other than to say they should have been set in under 5 minutes (lol) so I have cut back to the amount sugested earlier by I cant remember who (9 drops per 25ml) and bingo things seem to be working alot better. I wont know the full story for a few days till I turn them but they do seem better. The next problem becomes the joins I am using Sierra Tubes at present but getting the join right is an art on its on. I am looking forward to that template david but for now I am try all sorts of tricks to see what works and what doesnt. I will be sure to post the pic when something finally works out.

Ps I am still open for any ideas and thak you all for your help so far its great :2tsup:

Cheers Ian

[dj_pnevans]

As soon as he get's home I will get some made up.
David

[Resination]

A couple of things came to mind right away .. one is the hardener. As others have
mentioned, more catalyst can generate heat more quickly so you get a faster cure. But
the tradeoff is a more brittle blank.

This hasn't been the case for me, but I don't add as much as people would like to think. I did try different amounts early in my casting days and never seen much of a difference from the amount of catalyst. There is much more of a difference between brands of resin.

Also, the type of resin makes a big difference. Resins from a craft store aren't usually
meant for turning. People use those to pour into a mold and embed items, so a more
brittle resin is no problem for that purpose. But we subject the resins to some rather
harsh punishment with high speeds, cutting tools, hot drill bits, saw blades etc.
Some of the craft type resins are just not meant for this treatment and will crack or
chip out.

Resins in general are not meant to be turned. Brands do very in brittleness, but this is due to the chemical make up.

I often see people talking about turning blanks in a matter of hours. Keep in mind
that the cure may take several days even though it might be ready to de-mold in hours.

I turn blanks in as little as 1 hour from the time of pour and they are not flexible or soft. They are FULLY cured. This was proven at work on the Rockwell hardness guage between a blank just cast and one that was cast a week earlier. They guaged the same. This has nothing to do with the catalyst, but rather the process I use for casting. My blanks are fully cured in 1 hour and can be turned at that time without any brittleness. All my local customers will confirm this.



During that time, the resin is still somewhat flexible, so any stresses you put it under
can show up as air pockets around the tubes. You've got a lathe spinning the blank
at 2000 or 3000 RPM.. and a chisel trying to stop it instantly. That can put a lot of
flex in a resin that is set up and firm, but not really cured yet.

ok, that's all the ideas I have for now. :p


Just my opinion and everyone's results will vary. Best thing to do is experiment and keep documents of everything you do. Once you get the magical formula, just repeat it over and over and...

[munruben]

This has nothing to do with the catalyst, but rather the process I use for casting. My blanks are fully cured in 1 hour and can be turned at that time without any brittleness. All my local customers will confirm this...Great to hear, how about sharing your casting process in more detail.:2tsup:

[Resination]

John,
What works for me, may not work for you. It took me about 6 months to perfect my process and if any of the many variables are out of whack, I have to compensate.
I can tell you that a little over three years ago, I designed and built a forced air heat chamber (FAHC). It works for my set up. There are many casters now starting to catch up on this idea. I wouldn't do as most are doing, use an oven. Too many inherent dangers.
Mine not only warms the interior, but also circulates the air and exhausts the fumes. There are several chambers with baffles to keep the resin from being disturbed.
I also do not use a pressure pot. It's a waste of money in my opinion.

[munruben]

John,
What works for me, may not work for you. It took me about 6 months to perfect my process and if any of the many variables are out of whack, I have to compensate.
I can tell you that a little over three years ago, I designed and built a forced air heat chamber (FAHC). It works for my set up. There are many casters now starting to catch up on this idea. I wouldn't do as most are doing, use an oven. Too many inherent dangers.
Mine not only warms the interior, but also circulates the air and exhausts the fumes. There are several chambers with baffles to keep the resin from being disturbed.
I also do not use a pressure pot. It's a waste of money in my opinion.Thanks for that insight to your method. The FAHC idea is quite interesting. I am sure some of the other forumites will follow up on that. I was not aware of such a procedure. We learn a little every day.:)