Clear Casting Issue

Signed-In Members Don't See This Ad
D

Dr Robert

Member
Joined
Nov 11, 2015
Messages
31
Location
Kennett Square, PA 19348
I use a variety of resin materials, notably alumilite, liquid diamonds and Selmar. Recently I've noticed a shiny reaction of the Selmar around a few of my watch parts, particularly where the CA attaches the fixture. I try and be careful and not overdo the CA but sometimes I'll get some excess which is unavoidable. It almost looks like a shiny crystalline glaze. This is most noticeable on a dark background, black or brown. It shows when bright light hits the blank. Any suggestions??


Sent from my iPad using Penturners.org mobile app
 
Signed-In Members Don't See This Ad
I'm guessing it's where the Silmar isn't bonding and creates an air pocket.
Polyester can be fussy on what it bonds to. An epoxy or urethane would bond better, with epoxy being choice, since the urethane requires pressure.
 
Terredax said:
I'm guessing it's where the Silmar isn't bonding and creates an air pocket.

Polyester can be fussy on what it bonds to. An epoxy or urethane would bond better, with epoxy being choice, since the urethane requires pressure.
Click to expand...



Thank you for the reply! It is frustrating to spend a lot of time on the blank design only to have it botched with the resin!


Sent from my iPad using Penturners.org mobile app
 
I'll try to offer a suggestion without opening another can of worms. It's been discussed here and with several opinions the CA might be outgassing. I think it does so I'll wait 3 days after gluing to cast. I'm not sure if this pertains to you but might be worth thinking about. Also is it noticeable after it's turned? I've seen with several different blanks when something glossy is used under the resin it's noticeable after casting. When turned it's not noticeable be cause it's right below the surface. I guess you need to decide if it's separation or a reflection. Good Luck.
 
I have often put a coat of CA over labels or snake skin with no ill effects. But I do wait a couple of days to allow the glue to completely cure and outgas.

As much work that is required to get blanks ready yo cady another day or two wait before casting is not much. Your watch parts blanks even more so than my snake skins. Patience is worth having for clear casting.
Do a good turn daily!
Don
 
Thanx guys for your input. These blanks were left sitting for 4-5 days so the degassing issue should have been taken care of. The "crystalline" effect started to occur and become more pronounced as the polymerization progressed. As careful as I am to adhere small fixtures to the blank, I inevitably get a little excess CA on the border of the fixture and blank. I'm wondering if the Polyester chemically mixed with this or it ran under the CA...tough one. I really like the clarity of the PR but it's much more of a challenge than Liquid Diamonds or Alumilite.
OK..... One more issue... I started making Cigar pens. I turn the wood shy of the bushings....go thru the usual sanding and finishing to get as smooth a surface as possible. I applied the Cigar Label to the blank using Loctite's adhesive spray, sealing the edges and wrapped with small rubber bands to insure good adaptation. Three days later I tried clear casting with Barry Gross's PR...using 6 drops per ounce. I left in the pot for 24 hrs.....when I took it out, the resin lifted the labels in spots.....what do you guys use to adhere this type of label to a wooden blank?? Dr Bob is going crazy!!! LOL


Sent from my iPad using Penturners.org mobile app
 
It's in the same type plastic bottle the other comes in but the plastic and the glue is crystal clear. I used the white glue for a long time but it doesn't dry clear so on dark back grounds it would leave a light grey haze. The clear does not. I'll wrap the label to make sure it will stay flat against the tube then apply another coat to seal everything up. I've purchased it at Home Depot and Walmart.
 
Your problem is air. being trapped under labels watch parts or other cast on parts and not enough time to release with PR or alumilite resins even under pressure. Seal all parts before casting. I like to use Silmar and I heat the resin before I add catalyst to make as thin as possible. Can not speak for alumilite because I do not use it. I have now gone to Liquid Diamonds and to me this is the answer for casting things like watch parts because it sticks to everything and does not shrink and is very thin so gets in all nooks and crannies. Polishes just like PR and is as hard when cured. It gets my two thumbs up.
 
I agree!! Alumilite is very user friendly but definitely not as clear as PR. Liquid Diamonds on the other hand is less fickle and incredibly clear! Setting time is longer than polyurethane but not nearly as long as PR. The only problem is the price tag. Where do you guys buy it from??


Sent from my iPad using Penturners.org mobile app
 
Kenny....question...after you apply the label with Clear Elmer's, do you paint more on the external surface of the label??.....AND on the seal portion? I've found that if you get ever so little adhesive on the blank adjacent to the label, the PR will react with it to produce a haze or discoloration. You must be very, very careful in applying the adhesive.


Sent from my iPad using Penturners.org mobile app
 
Dr Robert said:
I agree!! Alumilite is very user friendly but definitely not as clear as PR. Liquid Diamonds on the other hand is less fickle and incredibly clear! Setting time is longer than polyurethane but not nearly as long as PR. The only problem is the price tag. Where do you guys buy it from??


Sent from my iPad using Penturners.org mobile app
Click to expand...

Statement not true. Liquid Diamonds is the longest setting time of any of those. Buy it from a vendor here Chad Schimmel at Turners Warehouse. Check vendors forums. He runs sales now and then. Depending on what you are doing price does not come into play. The more pens you do you will soon find this out.
 
When you use Silmar 41, how many drops catalyst per ounce resin do you use? How do you warm the resin? I would think the more catalyst the faster the set. Contacting the manufacturer they recommended 10 drops per ounce. I found complete polymerization takes 2-3 days!


Sent from my iPad using Penturners.org mobile app
 
Dr Robert said:
When you use Silmar 41, how many drops catalyst per ounce resin do you use? How do you warm the resin? I would think the more catalyst the faster the set. Contacting the manufacturer they recommended 10 drops per ounce. I found complete polymerization takes 2-3 days!


Sent from my iPad using Penturners.org mobile app
Click to expand...

That may also be your problem. 10 drops is recommended by the manufacturer. But that is when the resin is used for a thin clear coat. I use 4 drops per ounce for casting pen blanks. Hope this helps.
 
Dr Robert said:
When you use Silmar 41, how many drops catalyst per ounce resin do you use? How do you warm the resin? I would think the more catalyst the faster the set. Contacting the manufacturer they recommended 10 drops per ounce. I found complete polymerization takes 2-3 days!


Sent from my iPad using Penturners.org mobile app
Click to expand...

I too use 3 to 4 drops per ounce. If you are using 10 drops per ounce you are making the casting very brittle and will be hard to turn and become chippy. This is all that is needed for casting as we do. To heat the resin I place the resin in my toaster oven for about 15 minutes at 125 to 150 degrees. When I add catalyst I try not to stir too vigorously. When I pour in mold I try to let resin pour against sides of mold or use stir stick to prevent resin from splashing and causing bubbles. Anything you can do to help eliminate bubbles will help your final outcome. I also always use a pressure pot for Silmar and liquid diamonds. Silmar will start to set in about an hour or less. LD about 12 hours or more.
 
Dr Robert said:
Thanx so much....I'll give it try..4 drops it is.....two last questions.....typically how long does your polymerization take using 4 drops?? And do you warm the Silmar and if so how?? Dr Bob


Sent from my iPad using Penturners.org mobile app
Click to expand...

I put my silmar in a water bath for about 20 minutes. I'm guessing the water is about 100 to 110. I like the resin to be about 85 to 90. When doing color mixes, I pour at about 12 minutes. Different colors will vary the set up time, but generally, mine will start to set about 15
minutes after mixing the catalyst. But for clear casts, I mix the catalyst, let the bubbles come to the top (about a minute or two), then pour.
 
Last edited:
Dr Robert said:
Awesome guys!! Really appreciate the input... I would think the warm resin will speed up the setting time and also increase fluidity and reduce bubbles!?......yes????


Sent from my iPad using Penturners.org mobile app
Click to expand...
Warming will definitely speed up the set time. I can't swear that it reduces bubbles. To be honest, I really don't notice the resin being more fluid, but it probably is. However, over 95% of my casting experience is color casting. I've done some tube on casting, and have had very few issues, and non like you describe.
 
I use the Clear Elmers to seal the whole blank. I also use 3-4 drops of MEPK when using PR. Back to your original question I use CA when gluing watch parts or something I can't or don't want to set and hold or clamp. When using CA you have to be careful and sometimes after casting if you hold it up to the light you can see the reflection off the CA. Most of the time when you turn the blank that will disappear. I use a candle warmer to heat my resins. I pour the amount I need into a plastic cup and heat only what I need when I need it. I used to heat the whole bottle but I noticed the resin thickening and getting hard to pour. I even lost a bottle of PR due to it hardening in the bottle. Remember heat is what causes the resin to set.
 
You must log in or register to reply here.
Back
Top Bottom