New to casting

[wkuhn]

I recently purchased a casting kit from Barry Grosshttp://www.bgartforms.com/pen_kits_&_accessories.htm
after a demo at our club.http://www.baltimoreareaturners.org/
A few beginner questions if I may.
I made my base pour and after three days on my porch in 90+temps and high humidity the surface remained sticky, this also occured after my final pour- Is this normal?
I finally removed the casting from the mold and sanded the surface which removed the stickieness.
I the proceeded to turn my blanks and expierience a lot of chipout, which I successfully filled with ca glue. I never exp chipout with purchased acrylic blanks. Is this normal?

I believe this kit uses PR -5 drops of cat with each ounce of resin.
Question does humidity affect cure time?
Does too much catylist affect cure time or hardness of cast?
Can a heat gun help cure ?
Any tips would be appreciated.
I have attached a photo of my finished pen.
Thank you
Wayne Kuhn

 

[Glass Scratcher]

Originally posted by wkuhn

I recently purchased a casting kit from Barry Gross http://www.bgartforms.com/pen_kits_&_accessories.htm
after a demo at our club.http://www.baltimoreareaturners.org/
A few beginner questions if I may.
I made my base pour and after three days on my porch in 90+temps and high humidity the surface remained sticky, this also occured after my final pour- Is this normal?
I finally removed the casting from the mold and sanded the surface which removed the stickieness.
I the proceeded to turn my blanks and expierience a lot of chipout, which I successfully filled with ca glue. I never exp chipout with purchased acrylic blanks. Is this normal?

I believe this kit uses PR -5 drops of cat with each ounce of resin.
Question does humidity affect cure time?
Does too much catylist affect cure time or hardness of cast?
Can a heat gun help cure ?
Any tips would be appreciated.
I have attached a photo of my finished pen.
Thank you
Wayne Kuhn

That is a very nice looking pen and a good first cast.

Many polyester resins (thick casting or thin) are LAMINATING resins. Castings stay sticky on the surface so you can cast another layer and they will bond together better. You can post cure your castings in a 125 deg F toaster oven for 15-30 minutes and this will cause the outer layer to cure.

Humidity can affect cure time.

Temperature can affect cure time.

The amount of catalyst has the effect of accelerating the cure of the resin. Some (myself included) believe less is better. Some believe more is better. You will need to experiment and decide. I like to go with 3 or 4 drops of MEKp under normal conditions. Chilly and rainy I may go with 5 but that is my limit. Some colors require less catalyst(red and yellow, orange and green). Some colors require precatalysing the resin before adding the pigment because they will cause cure inhibition (white and black paste dyes fall into this catagory)

A heat gun can affect the cure. So can preheating your molds.

 

[sbell111]

Some timesd I think I have my method down and the resin is still slow to cure. Generally, I set those outside to bake in the sun for a bit and they are fine.

 

[stevers]

Wayne,
Humidity does affect cure time, but not generally brittleness.

5 drops is average or even a little high, cooler temps can require more catalyst.
Side note,,, some coloring additives can also alter cure times, especially liquid colorants.

Stickiness is common. It usually has no affect on the resin, it's only on the surface. Most of my casts are sticky for several days. If I want to turn them sooner, I just trim off the sticky part.

Some folks here have experimented with heat to cure their resin. Generally, the warmer it is, the sooner it cures. The catalyst causes a chemical reaction witch induces heat to speed the curing process.

As for the chipping, sharp tools can help. If it seems to be with the home cast more than the store bought, it may be something you will have to get used to. There is an ongoing debate as to whether more catalyst alters the resins brittleness. You will get lots of diff answerers to that question.

 

[wkuhn]

Hey guys thanks for the replies-
In Summary
Warmer Temp = Faster cure less catylist
High Humidity= Slower cure? (not sure about this one)
Sticky surface= Normal
Colors will have an effect on cure
Chipout= Poor tool edge or poor technique
I believe I got my answers
Thanks for the info.
Wayne

 

[stevers]

Yes on all. Good luck and have fun.

 

[JStein]

Wayne,

Looks great.

I am planning on joing the Baltimore Area Turners in July. My brother belongs and he mentioned that Barry Gross was there at the last meeting.

I'll look you up at the next meeting.

Joe Stein

 

[wkuhn]

Looking forward to it Joe.
Our July meeting is a show and tell and general discussion.
August is a demo by The Big Man Himself- Bill Grumbine.
We have some very talented people as well as beginners.
Great group of guys and gals, lots of fun.
See you on the 9th,
Wayne Kuhn