Handy tip for press molds

[Shawn R. L.]

Been messing around with some press molds lately and trying some new things.

1----I made the mold part out of Pro Create since it\'s slightly elastic - won\'t shatter when getting the finished piece out.

2----I used car wax as a release on the master and on the molds when used to cast parts. So far, this is the best release I\'ve used. The parts don\'t fall out but they are WAY easier to get out......intact.

3----I\'ve been using JB Weld two part epoxie/putty/goop, used for engines and such. Sets up hard in about 5 minutes and is VERY HARD and workable.

Hope this helps.

 

[freakinacage]

got any pic of finished pieces and the moulds themselves?

 

[A Luna]

pics, yes please or it never happened

 

[Einion]

1----I made the mold part out of Pro Create since it\'s slightly elastic - won\'t shatter when getting the finished piece out.
Better than GS?

Not as good but worth knowing, even with rigid epoxy putties like MagicSculp you can get them to flex quite a bit by heating with a hairdryer or dipping into hot water, if you need to release something from a mould for example.

2----I used car wax as a release on the master and on the molds when used to cast parts. So far, this is the best release I\'ve used. The parts don\'t fall out but they are WAY easier to get out......intact.
Presumably better than talc, yes? Car wax seems like a great idea. What have you compared it to?

3----I\'ve been using JB Weld two part epoxie/putty/goop, used for engines and such. Sets up hard in about 5 minutes and is VERY HARD and workable.
Any idea how it compares to A+B or Apoxie Sculpt in terms of hardness?

Einion

 

[Shawn R. L.]

@freakinacage & A Luna Not much to show really. Mold, car wax and tubes of epoxy...

@Einion
1---Haven\'t tried GS yes but am told it\'s basically the same.

Didn\'t know that about Magic Sculpt. Thanx.

2--- I\'ve tried talc, vasalene, cooking oil, some sort of engine, silicon lube. The first three worked OK. Not great.....got the job done....usually. Talc left a grainy surface and on tiny pieces it showed big time.

3--- Not sure about A+B, never heard of it. JB Weld cures hard to the point of being brittle, which suits my purposes just fine. It carves smoothly and sands just fine.
JB Weld mixes up to about the consistency of thick syrup. A bit of a trade off here but through some thought, trial and error I\'m getting around the problem of bubbles. What I didn\'t like about using putty in push molds is that you could still end up with hollow\'s and the problem of \'fold lines\'. Also having to press so hard to get the two halves of the mold to contact. With the JB Weld there is almost no mold line.

 

[freakinacage]

is this for one sided moulds only?

 

[Einion]

2--- I\'ve tried talc, vasalene, cooking oil, some sort of engine, silicon lube. The first three worked OK. Not great.....got the job done....usually.
Read lots of good reports of thinned vaseline as a release for casting (even with resin) even just using it brushed out thinly with a soft brush. I haven\'t tried it myself as I don\'t keep any in the house.

Furniture wax brushed on with spirit-dampened brush worked well. One plus is that it doesn\'t seem to be stripped entirely from the mould with each pull so it doesn\'t have to be reapplied. But it does tend to build up in the recesses.

Talc left a grainy surface and on tiny pieces it showed big time.
Yeah, you certainly have to take care when using talc if there\'s any fine detail to leave only a trace in the mould and removing excess from divots is a must or there will be actual voids in the cast.

Worth using if it\'s the only thing on hand but there are better releases, especially with any material that\'s really adhesive.

3--- Not sure about A+B, never heard of it. JB Weld cures hard to the point of being brittle, which suits my purposes just fine.
Wanted to check as I\'d heard \"JB Weld is tougher than aluminum!\" The goopy consistency certainly makes it sound like something I\'d like to try for the reasons you mention - no need to mash putty into the mould and hope it fills all the recesses!

A+B is one of the earliest epoxy putties co-opted for use in sculpting. One version goes very hard, so hard it\'s nearly impossible to carve when fully cured. Very strong though, so great for solidifying armatures for example.

Einion

 

[Donga]

Pictures now please

 

[Shawn R. L.]

Here\'s the mold, set in a wood block with locater pins.

This is the copper master and copies.

 

[freakinacage]

impressive

thanks for that

 

[Gapow]

Will press moulds work with milliput? I\'ve ran out of GS and wanted to try some out tonight

 

[freakinacage]

yeah

 

[Shawn R. L.]

Originally posted by Gapow
Will press moulds work with milliput? I\'ve ran out of GS and wanted to try some out tonight

I don\'t see why not. Seems that most anything can make a mold or be used for molding material. The big trick is getting said material OUT of the mold.....intact.

 

[Shawn R. L.]

Another plus I just found out last night with using the JB Weld is that if you try to take the piece out of the mold soon after the cure time, it\'s still quite flexible and even easier to remove.

 

[Einion]

Posted that tip before; I try to pull things out of press-moulds when the material is still just about rubbery or \'leather hard\'. Most epoxies go through a stage somewhat like this which is a good window to remove it from the mould - especially worth doing if the mould is rigid.

But if you have to leave something in the mould because you\'re at work (or you forget!) heating it up well will give close to the same amount of give that\'ll allow something to flex out of the mould more easily.

Einion

 

[Shawn R. L.]

Heating it up?? How hot? Warm or HOT.

 

[Einion]

My standards for heat on my right hand are raised from cooking so I\'d have to guestimate, so very warm to uncomfortably hot?

Just until it\'s noticeably warm - say 15 seconds on high from a hairdryer - can work okay but if you get it hotter it\'s noticeably more flexible, so a brief soak in boiled water can be worth trying if there\'s any difficulty.

This is particularly evident when the putty hasn\'t achieved a full cure, so within 12-24 hours of mixing. Past about 48 hours putty is generally as hard as it\'s going to get so you have to get it hotter for best results.

Einion