2 Questions to Ask.

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Celt40

Member
Joined
Nov 26, 2007
Messages
119
Location
Scotland UK
1. How much PearlEx pigment do i add per 1oz of PA resin. I know it depends on the colour dark/light.

2. I cast an 8oz mold with PA resin and coloured it with paste. Then i added dark exotic wood shavings and filled mold to the top. This was done over 3 weeks ago, but the casting is still soft.

Has the wood stopped the resin setting. Do i need to use a pressure pot??[:I]
 
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While there aren't any up there (yet) using PearlEx, you can probably get a general idea from
my color library:

http://www.rziha.net/woodworking/experiments/resin_color_library/

Is the casting soft as in
1) runny-honey thickness or thinner
2) gelled but not solid - kind of jell-o
3) Pretty hard but still tacky on the surface?

While the last is easiest, the remedy for all is basically time and heat.
(actually, if the first, you *might* be able to add more catalyst.)

I've lately been setting my molds on top of my (black) garbage can with a clear dome (1gal juice carton with the bottom cut off) on top. Makes an effective solar cure accelerator.
 
Thanks for your reply's

1. I used 5 drops of catalyst per 1oz of resin.

2. No 2 Gelled but not solid. Spongy when pressure applyed.

Over here in Scotland the temp during the day only reaches on average, day time 18c & night 9c. I moved the mold into the direct sunlight during the day, and then moved it back into my shed during the night. I thought that the heat during the day time would speed up the setting of the resin.
 
Dermot...I too am new to casting and I've experienced trouble with setting up. I'm in the Pacific Northwest where we have been lucky to get out of the 60's this spring...unusually cool and wet from my memories...

I have had a lot of trouble getting the initial gel stage timed out for the secondary color add...have tried several different methods, none very good yet. I too set up castings out into the sun (when we see it) and seem to be getting solid set in about 48hrs. I used 4-5 drops per ounce in the PR.

I read somewhere that one person was setting their mold into a oven at about 150 degrees to speed up the initial setup..have thought about trying that with a old toaster oven I have but probably look for a lower temp...

Can't help on the pearl ex, apparently I'm not using enough at the right time as it is not working out to well.

Keep testing and let us know what you find.

Doug
 
Temp does affect it. 5 drops should work even though I usually use a little more than that. I have used way too much pigment a few times(by accident, it dumped on me) and that has never seemed to cause a problem. I haven't had any problems with moisture or water in the mix as others have but, could your would have had excess? Maybe an oily wood? I would think, if it is gelling, it should set. Good luck!
 
I've had some woods that made the PR never set. I can't remember what wood it was though. A dark one, I do remember that.

GK
 
I don't remember the name of the wood as the lable has came off. It is a bit on the oily side, this must be the reason. Will just have to wait a bit longer to see if it will set no worries.

The gel time here is a bit of a pain, i can wait over 4 hours if i cast in the evening for it to start to gel. Not handy as i have to remember to return to shed to set up for the second colour...Rats

Oh the joy's of penturning[:p]

Doug keep in touch with your casting, we might be able to learn off each other.
 
I use from 10 to 20 drops of MEKP per oz depending on the ambient temp (MEKP casues a chemicial reaction which generates the heat needed to cure the resin....more MEKP more heat) and my blanks all cure in about 6 hours but I let them sit for a day to fully cure .
I used 3 or 4 drops of hardner and was having all kinds of problems during the winter getting them to cure in less then a week until I pushed the hardner amount up .
A word of caution about alot of hardner , Your blanks will be more brittle with increased hardner however I LOVE brittle blanks and find the extra hardner makes them just about right for my way of turning (VERY sharp skew and light shearing cuts from start to finish) .
This is not the solution to everyones problem but it works for me .
Oh by the way I was trying to cast some semi green maple burl so water may have been at work too .
 
10-20 drops. Wow.

I use about five. This time of year, if the blanks aren't good and hard in four or five hours, I just set them outside in the sun for a bit.
 
I know what you mean about using 10+ drops per 1oz. I made a batch of blanks using 10 drops of MEKP. Looked okay but some shattered when i was turning them. Other than that they were just as good looking as the bought blanks.

Not good for my way of turning. I am not what you would say very delicate.
The Acrylic blanks like Polygem and others sold by the big companys. What amount of MEKP would they use?. The bought blanks seem more constant when turning ( breakage wise )
 
I just cooked up a batch of blanks last night with 10 drops and by this morning they were all rock hard and ready to turn .
They turn just like acrylester blanks , with a sharp skew you just need a little touch up sanding and then polish with white diamond for a perfect finish .
I have been experimenting with the amount of MEKP to find the best mix for cutting clean threads and have found so far that 7 to 12 drops gives clean threads without any sign of melting and no tear out , so for my purposes 10 seems like the right amount for me and it also helps with the cure time and temperature ranges .
I have no damp (?) worthless wood to try it on at this time so Im not sure if this would help with that.
The 20 drops are only used when the temp gets down to around 50 deg here in the shop and with the heatwave we are having right now i could use as little as 7 but I'm sticking with 10 for consistency
 
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