Air bubble filler

[darkjawas]

been castinf in smooth on 300 resin
using both urethene rubber and silicone molds
every so offen i get minor air bubbles in my prop castings

since there small and bondo would be over kill
what would be a better type of filler to use
one that can be sanded/ filled down
and min waste ie squeeze tube ect
thanks

 

[Zombie_61]

For small air bubbles, Bondo Glazing and Spot Putty:

http://solutions.3m.com/wps/portal/...CEK3_nid=FLPZ9HDTFTgs7J9PJJDH0LglJJRZ9H3FL5bl

One-part, pre-mixed, available at just about any auto parts store. Easy to use (though it has a relatively short working time, maybe 5 minutes), and sands easily without flaking once it's fully cured. Some shrinkage, so not recommended for larger voids.

For larger voids and/or adding minor surface detail, Aves Apoxie Sculpt:

http://www.avesstudio.com/index.php...page.tpl&pop=0&option=com_virtuemart&Itemid=4

Two-part epoxy putty, relatively easy to use, can be smoothed (and tools can be cleaned) with ordinary tap water, practical working time of 45-60 minutes (despite what the manufacturer says). Bonds well and no shrinkage, but it's often harder than most resins once it's fully cured (which can sometimes make sanding/blending difficult; I recommend sanding before it's fully cured). Realistically you could use this for small air bubbles as well, but it's thicker than Bondo Glazing and Spot Putty and doesn't "flow" as well.

Two tips about working with Aves Apoxie Sculpt. First, like most two-part putties, the two equal parts must be mixed very well. Second, immediately after mixing it's rather tacky/sticky; mix it and let it sit for 10-15 minutes, and you won't have this problem.

 

[swgeek]

For small air bubbles I use a medium CA glue.

 

[dragehest]

you can also try putting a little bit of talcum powder in your mold, the powder breaks the surface tension of the liquid resin and you will greatly reduce the annoying out of nowhere bubbles.

 

[darkjawas]

thanks ill try a few out and see what works the best

 

[Darth Humorous]

you can also try putting a little bit of talcum powder in your mold, the powder breaks the surface tension of the liquid resin and you will greatly reduce the annoying out of nowhere bubbles.

Do you put the talcum powder over the mold release agent, or do you use it in lieu of mold release agent?

Mark

 

[robn1]

For very small bubbles I've had good results with Tamiya Surface Primer. It's a thick primer/thin putty type stuff, I usually apply it to small holes with a toothpick.

 

[swgeek]

Do you put the talcum powder over the mold release agent, or do you use it in lieu of mold release agent?

Mark

If you're casting out of silicone molds you don't need release.

 

[Wesman]

If you're getting bubbles in the same place every time, cut a small vent channel to the spot. You can also try tilting the mold and slight tapping while the resin is still liquid.--Wesman