Jump to content
gumbyness711

Quick Pop Question

Recommended Posts

hello everyone, I am fairly new to making my own molds..I started out trying some 1 part POP molds and all of them were successful.  I recently made my first 2 part mold, and when I took the pieces apart the insides were completely black with mold...I really don't know how this happened because i only let it set for 24 hours and it was left in room temperature the whole time..i used petroleum jelly as a release agent, and sprayed the bait with pam before pouring the 2nd part...could this have happened because i didn't seal the first piece with glue before pouring the second?  this is the only thing i can think of...any suggestions would be greatly appreciated, thanks

Link to comment
Share on other sites

I use a wax floor tile polish, but that is just because I found a tin of it when I moved into the house. It works good, but it is thicker than PJ. After applying to the master, I wave it over a gas flame, just to smooth it out.

 

If you have some then by all means give it a go, if not then stick with PJ, it is what most TU members use.

 

Dave

Link to comment
Share on other sites

I use cooking oil . It gets into every nook and cranny. Just don't use too much(flooding). I use a small artist brush to spread it around. The oil will soak into the pop. Try not to put it on the master though.

After the mold sets up and I can separate the 2 parts( maybe 2 or 3 hours) I put the 2 parts in my oven at about 150 degrees; checking every 1/2 hour. Take it out and set it on old newspaper for a bit. This will suck water right out of the pop. Then return to the oven; repeating till dry.

 

I can make a mold in the morning and be pouring by mid afternoon.

 

Works good for me.

Link to comment
Share on other sites

thanks guys, this is some really good advice, I had no idea newspaper would soak up the water out of the pop...I have one question though, what are you guys referring to as the "master"? and it seems like conflicting ideas because vodkaman is saying apply to the master and nova is saying don't put it on the master

Link to comment
Share on other sites

The "master" is the item that you are making your mold with. If you put the oil on the master it will bead up especially if it is a plastic bait; and this will cause defects in your finished mold.

I can't speak to using wax as I have never used it. Paste wax can be hard to find,

 

Dave; don't know about being a master mold maker. If that means I made a lot of mistakes over the years then I guess that's me; lol.

 

Mking mistakes is the best way to learn. You tend to remember what you did wrong much better.

Edited by nova
Link to comment
Share on other sites

The mold is purely from the fact the POP mold wasn't dry.  I have had it happen a few times when I was experimenting with different ways to make molds early on.  Just store them open when first made.  Many like to bake the molds but I never really found the need or it to make any better product.  

Link to comment
Share on other sites

thanks guys, I knew it had to be a moisture problem, I just didn't see how this could have happened in 24 hours in room temperature...also, I had been told and read on more than one occasion to add oil to the master to help it pull out of the mold easier but if this is going to potentially cause defects I will not try this anymore...also travis, the mold happened before I took the two pieces apart for the first time...I poured the 2nd piece one night and when I got home the next evening and took them apart it had mold all inside, especially around the master which in this case was oven bake clay. 

Link to comment
Share on other sites

Other people seem to be letting the two part pop set up longer than I do. I usually demold and pull the two pieces apart as soon as the plaster sets, usually 20-30 minutes, then I let the two pieces dry separated.

24 hours does seem really quick for mold to show up though.

Link to comment
Share on other sites

Other people seem to be letting the two part pop set up longer than I do. I usually demold and pull the two pieces apart as soon as the plaster sets, usually 20-30 minutes, then I let the two pieces dry separated.

24 hours does seem really quick for mold to show up though.

That's the same way I do mine but I useually wait an hour before I separate the mold. Then right into the oven.

Link to comment
Share on other sites

I believe I have been mixing a little too thin because theres no way mine will set that quickly but im sure ill have it perfected after plenty of trial and error...I really appreciate all the advice

If you use too much water (too thin) the mold will not hold up. It will be kind of powdery after a while and start to break down. I don't measure anything; I do it by eye and feel. But you don't want it too thick either as the thick plaster may not fully conform to the master in all areas.

Link to comment
Share on other sites

While you are new to PoP, measuring is a good idea, so that you can repeat when you get it right. But I guess with experience, measuring would not be necessary. Being me, I always measure :)

 

Oven drying is fine as long as you don't over cook. Once all the water has been driven off, the mold will rise in temperature. If the temp of the mold is raised above the critical temperature, the mold composition will start to revert back to its original formula and will become powdery.

 

I built a fan assisted drying oven specifically for PoP and other low temperature applications, heated by 3x 100W filament bulbs. This works very well, but obviously takes longer than a cooking oven. A search for 'PoP oven' should bring up the thread.

 

Dave

Link to comment
Share on other sites

this is some really good insight, I really appreciate it...I poured a senko mold last night with two cavities and took the two pieces apart this morning and let them air dry while sitting on newspaper...once I got home I started baking in the oven and it appears to have set really nicely...now if I could only get better at taking the two pieces apart.  anyone have any tips or tricks other than the obvious?

Link to comment
Share on other sites

A coat of paste wax or vasoline works fine.  I brush it on the wipe/buff off leaving just the bare minimum.  Some will use foil and lay over the wax to increase the ease of separation but I find it just one more thing to mess with.  

Link to comment
Share on other sites

I use vaseline between the pieces, when I separate them I take a chisel, place it along the seam away from any of the baits parts, and I give it a quick tap. Usually separates them cleanly, with the only damage being a little chisel mark. 

Link to comment
Share on other sites

I mix my pop 2 parts pop to 1 part water, the stuff is so cheap I don't worry about wasting it. Use cold water for longer working times. After the bottom has set for a while 30 minutes to 1 hour, I mix and pour the top half I also use PJ it works fine, I separate the molds as soon as I feel they will not break and let them cure in separate halves. When I'm in a hurry (always a bad idea) I heat them in the oven otherwise I just let them dry on the counter. I have a 6 part video on making a two part mold.

Link to comment
Share on other sites

If you are pouring decent molds they actually come apart pretty easy, I noticed a lot of people have a lot of trouble with PoP, but seldom do they follow the mixing instructions, I find measuring the PoP and water and using cold water solves most of my problems. I also use tapered flexable containers as it allows the molds to come out easily. Don't be afraid to use extra PoP, I always use two cups for every pour so I have good molds to work with. When you mix the PoP 2 - 1 you should be able to coat the mold with PJ in 30 minutes or so then pour the top half in another 30 mins you should be able to lightly score the halfs all the way around and work the razor blade between the halfs like a screw driver it will separate almost instantly.

Putting this on my video to-do list.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...


×
×
  • Create New...
Top