"Air Bubble" free resin......feh

General Discussion General Modeling Discussion
1

I just love adds that claim this. Yeah, well…my casts have more air bubbles than swiss cheese caused by the curing process.

Wrote same comapny and thier responce was that something either was wrong with my mixing ratio or molds.

Gee, it’s real hard to screw up a 50/50 mix using measuring cups and a gentle mix with a flat stick to minimize air bubbles. As for the mold, it’s plastine clay - nuthin wrong there either.

So, how do I know it’s the curing process? Easy…just left some in the mixing cup to cure. what started out as no bubbles ended up with more bubbles than is necessary to bother with.

Ah well… back to aluminite. At least I know I’ll get a clean cast.
Lesson : Don’t believe everything that is touted by a manufactuerer or supplier.

2

Hmmm, never used plastine clay, all my molds are either RTV or Silicone.
Grind old molds down to use as filler for new molds.

Said that never seen anyone claim that their resin will produce bubble-free casts as it is an imposibility to guarantee, IMHO.

I prefer long glass swivels for mixing and pouring resin as no air can be trapped on them and the cleanup is a zinch.

3

What brand gave you trouble?

4

micro mark

5

perhaps try banging the resin just before pouring ? i mean bang it really really hard to get the air bubbles out. some time ago i did some plaster figures from commercially available molds and i had bubble problems until i banged the mixture hard. i do appreciate that resin is different from plaster, though. does the resin involve water ? if you are using tap water maybe try boiling the water before using it, dissolved gas may be the cause of the bubbles.

at the end of the day micro mark might just have a product that has fallen short of the mark.

6

I’m using their CR-600 resin now and it doesn’t seem to be bubbling on me very much. You might try dusting the mold with plain talc powder before your pour.

7

One other thing that can cause resin to bubble is moisture in the mold.

Regiethedorf banging the mold is also recommended for resin casting, as it speeds up the ratio of air escaping.
Most times that air gets trapped in the resin is when mixing the components and when pouring the resin into the mold. Resin curing time and mold design/layout also matter.

Also are we talking major bubbles or more along lots of pinholes??

8

actually after thinking about it you dont want to bang liquid resin, you probably just want to tap it vigourously. its pottery that you want to bang.

9

Wibhi2,
Your problem stems from 1 thing and 1 thing only…water. I’d bet my house on it.
Polyurethane casting resins are extremely hydroscopic (they will absorb water like a sponge). The exothermic (heat generating) reaction upon mixing the two parts together creates heat, which makes the water want to precipitate out of the mixed resin…causing bubbles.
I always use what’s called a “dry air blanket” when I decant my resins…it’s an anhydrous (doesn’t absorb moisture) inert gas that displaces the air in the jar or bottle…you just spray it into the container with the resin, quickly screw on the cap, and prevents the resin from absorbing that water…it will increase the shelf life of the resin in the opened containers.
Make sure that you NEVER pour resin when it’s raining or on days with high humidity…cuz once the moisture is absorbed by the liquid resin, it’s time to throw it away and buy a new batch…