Tips from a pro... Base bleed

[Munkey Joe]

OK well Im LOOKING for tips from a pro.

Heres my story. Im casting some bases. Everything goes well, until I remove my masters. My mold is getting "bleed" from where I attach my masters to my foamcore. now I can actually deal with it, as I am just peeling the "bleed" off of my molds, but its not professional and I know its not right. it leaves a ragged edge that sometimes affects the cast. How do the pros do it??

Im using Hot glue to attach my bases to foamcore. I place the foamcore in my lego box and pressurize it to 60-70 PSI. this is forcing silicone under my attached bases i know but how do I attach them better and seal the edges to prevent this?? do I use different glue? do I use MORE hot glue and use it as a seal??

So im looking for input from the pros...... Jeff, Bec, and Zac GO.....

(PS this list of members is not exhaustive by any means... just those who answer quick!!) And if this is posted someplace else please delete it and PM me the link...

[Barn]

Well im far from pro lol...

I have only had this happen on one base (so far) and that was one that was a resin 'blank'. I do know why though.

I had a slight advantage in working it out, as I stuck my bases to a piece of glass. I also use PVA glue. Looking underneath, I could see that under the base made from resin (therefor a solid base) the PVA 'withdrew' if you like from the edges into the centre of the base, where it was slightly more hollow.

On the GW bases, where had carfully painted a thin line of PVA right around the edge, it stuck perfectly and formed a full seal.

Thinking of it, I actually have the next lot stuck to glass waiting for me to buy some more silicone, so i'll try and grab a pic and see if I can show what I meen.

[mangozac]

OK so I have it some thought and here's what I would do:

Glue the bases down to something hard - glass like Barn mentions would be best, but a tile or something similar could also work. I suppose MDF or even melamine would also work fine.

I'd use a small dab of Zap-a-Gap in the centre of the base - small enough that the bond will break without excessive force.

Then using some clay (i.e. plastecine; oil based clay) and a sculpting tool run the clay around the edges and seal up any slight gap between the base and the glass/tile/whatever. Force the clay in and clean it up like you are filling a gap with Milliput or GS. Remember that water works fantastically as a lubricant when working with clay too.

I know that sounds like a pretty time consuming technique - it probably is! I'll be interested to hear if the other "pro's" have any better ideas.

[Barn]

I think thats an excellent suggestion

[blind pig]

When I'm casting bases I use a large ceramic tile or my granite kitchen benchtop

I use PVA for GW type bases or, as Zac said, or a very small smear of Klean Clay (like plastacine without the sulphur) around the underside and clean the edges of resin bases.

[Munkey Joe]

Man.... its what I was afraid of.....

the clay monster.

oh well no more shortcuts then. It looks as if this is the way!

[Duckster]

What I do is take a blank base - hot glue it upside down to the bottom of the master base and then hot glue that one to the bottom.

This helps a lot in avoiding the dreaded 3/4 full base - you know when you fill it all the way , then somehow it shrinks enough to look concave or even when you don't have the mold completely flat in the chamber

When I fill the mold with resin just try to go slightly past the middle line where the 2 bases meet and then I clean them up later on the belt sander - I dip my bases in water while I sand them to cut down on dust. Buy an expensive respirator -those little dust masks are pretty useless. I would suggest a half face for anyone who sands more than once. I have already had I'll effects from breathing in the resin dust
- it hurts like heck for a few days and your lungs feel sore as anything

good luck

[Dragonforge]

Not sure what else to tell you other than use a good adhesive and make sure they are glued down properly. All my masters go permanently into their mold boxes. Ive 100's of them now..yes it is becoming a storage nightmare lol

You can buy a small pair of curved surgical scissors of ebay to trim the silicone "flash" if need be.

[Lane]

[quote="Dragonforge" All my masters go permanently into their mold boxes. Ive 100's of them now..yes it is becoming a storage nightmare lol
[/quote]

But saving even an hour of labor a week is significant. Having each mold turn out the same, thus consistent quality and mold life, is important as well.