Any ideas on what plaster would be best for making a mold used in a Fedora Block?
Any other material suggestions I would also appreciate, such as the cylinder for the actual mold.
Plaster for making a mold used in a Block.
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Renderking Fisk
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I seem t othink that Dakota Ellison made one by pouring Bondo into one of his old Federations (GASP!!! 
) But it worked out pretty well.
There is alway the concrete route too!
I'm thinking plaster wouldn't hold up well to a moist hat body and would probably at the very least get all over the inside of the hat.
I also think that Pyoxene made one by glueing a couple of 4x6's together and started sanding...
) But it worked out pretty well.There is alway the concrete route too!
I'm thinking plaster wouldn't hold up well to a moist hat body and would probably at the very least get all over the inside of the hat.
I also think that Pyoxene made one by glueing a couple of 4x6's together and started sanding...
I have made several custom blocks from plaster and have found that it works quite well. I simply use a high-grade artist plaster commonly used for casting and sculpting. You should be able to pick it up at any art supply store. What I do to create the cylinder for the block is to first cut out an ovoid shaped piece of foamcore that is exactly 22.5 inches in diameter (I wear a hat between 7 1/8 and 7 1/4). The shape I use I actually traced onto the foamcore from the sweatband of a hat that fits very well - so my blocked hats are already formed to the shape of my head. This piece of foamcore serves as the base of the cylinder.
From this point I build "sides" to the cylinder by carefully measuring and cutting out a piece of sheet styrene plastic (the stuff used in those cheap "for sale" signs) that measures 24 X 6 " Six inches because of the height, and 24 because this plastic will wrap around the base (with an inch and a half of overlap - getting enough overlap is important, otherwise the shape of your cylinder will warp as it nears the top). I attach this loop of styrene to the base with hot glue, making sure that none of it bubbles up into the inside of my mold. I fill any gaps with elmers glue as a filler.
At this point the basic structure is made, and it looks like a mini wastebasket of sorts. It may be necessary at this point to add additional styrene (or posterboard) around the first layer to add stability - you do NOT want your mold to warp when the plaster pours in, the sides need to be sturdy. I always reinforce them by looping three parallel rows of duct tape around the outside as a final step - near the bottom, the middle and the top. These really help the little oval mold keep it's shape.
You are now ready to pour the plaster in. Be sure to mix one part plaster with one part water - despite the fact that many instructions will say otherwise. My experience has yielded this as the best mix for this particular project, it makes sanding later easier. Don't add extra water or otherwise your plaster will be brittle and will take forever to dry. When mixing the plaster, add water to the bucket FIRST, and then, using your hand as a sieve, put little bits of plaster in at a time, crushing any clumps as it goes in.
Once you have your plaster mixed (and you always need more than you think, I use two whole large packages of plaster) get your hands in there and start mixing even more, you will feel it getting warm as the chemical reaction takes place that will eventually set the plaster. When the consistency is like pancake batter, it is time to pour it into the mold. Work fast because plaster can harden very quickly!
Pour or scoop the plaster in the mold to fill it up. At this point...all you need to do is wait. The plaster should harden quickly. After about a day or so you take the mould off, basically ripping it apart. What you are left with is a huge block of plaster, still easily scratched. Let the plaster dry for a few days - it will still be semi soft when you return. At this stage you can use tools to begin chipping away parts of the plaster to rough out the dome of your new block. Go slow and don't worry about the finer details like the smoothness quite yet, just get the basic shape roughed.
At this stage you need to really let the thing dry. My last block, which I am in the process of sanding, took three weeks to fully dry out because I added a bit too much water. When it is fully dry, now comes the sanding stage. All you need to do is sand, sand and sand some more. You can work out inconsistencies or shave down certain parts if you wish.
When you are all finished, you may shellac the block to protect it from the moisture of a wet hat, and to save your hat - you don't want to get dried plaster wet. What I do instead, is simply stretch a thin plastic grocery bag over the block and then put the hat over this. It keeps the block from getting wet and is thin enough to not effect the shape of the hat.
That's pretty much it as far as making a plaster block goes, or at least as far as I go when making a plaster block. It's great to be able to make custom blocks for all your hats.
-John
From this point I build "sides" to the cylinder by carefully measuring and cutting out a piece of sheet styrene plastic (the stuff used in those cheap "for sale" signs) that measures 24 X 6 " Six inches because of the height, and 24 because this plastic will wrap around the base (with an inch and a half of overlap - getting enough overlap is important, otherwise the shape of your cylinder will warp as it nears the top). I attach this loop of styrene to the base with hot glue, making sure that none of it bubbles up into the inside of my mold. I fill any gaps with elmers glue as a filler.
At this point the basic structure is made, and it looks like a mini wastebasket of sorts. It may be necessary at this point to add additional styrene (or posterboard) around the first layer to add stability - you do NOT want your mold to warp when the plaster pours in, the sides need to be sturdy. I always reinforce them by looping three parallel rows of duct tape around the outside as a final step - near the bottom, the middle and the top. These really help the little oval mold keep it's shape.
You are now ready to pour the plaster in. Be sure to mix one part plaster with one part water - despite the fact that many instructions will say otherwise. My experience has yielded this as the best mix for this particular project, it makes sanding later easier. Don't add extra water or otherwise your plaster will be brittle and will take forever to dry. When mixing the plaster, add water to the bucket FIRST, and then, using your hand as a sieve, put little bits of plaster in at a time, crushing any clumps as it goes in.
Once you have your plaster mixed (and you always need more than you think, I use two whole large packages of plaster) get your hands in there and start mixing even more, you will feel it getting warm as the chemical reaction takes place that will eventually set the plaster. When the consistency is like pancake batter, it is time to pour it into the mold. Work fast because plaster can harden very quickly!
Pour or scoop the plaster in the mold to fill it up. At this point...all you need to do is wait. The plaster should harden quickly. After about a day or so you take the mould off, basically ripping it apart. What you are left with is a huge block of plaster, still easily scratched. Let the plaster dry for a few days - it will still be semi soft when you return. At this stage you can use tools to begin chipping away parts of the plaster to rough out the dome of your new block. Go slow and don't worry about the finer details like the smoothness quite yet, just get the basic shape roughed.
At this stage you need to really let the thing dry. My last block, which I am in the process of sanding, took three weeks to fully dry out because I added a bit too much water. When it is fully dry, now comes the sanding stage. All you need to do is sand, sand and sand some more. You can work out inconsistencies or shave down certain parts if you wish.
When you are all finished, you may shellac the block to protect it from the moisture of a wet hat, and to save your hat - you don't want to get dried plaster wet. What I do instead, is simply stretch a thin plastic grocery bag over the block and then put the hat over this. It keeps the block from getting wet and is thin enough to not effect the shape of the hat.
That's pretty much it as far as making a plaster block goes, or at least as far as I go when making a plaster block. It's great to be able to make custom blocks for all your hats.
-John
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Relic Raider
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Careful with the plaster. You do not want to stick your hands in there to mix it. Plaster contains potassium sulfate, alum, borax, and lime, all of which are more or less toxic. Plaster contains also acetic acid, which is highly corrosive. When plaster hardens, there is an exotherm reaction, which can create enough heat to blow up a mould. Wear protective rubber gloves and goggles. Lime in the eye isn't fun.
Cheers,
-Relic Raider
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-Relic Raider
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Renderking Fisk
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Renderking Fisk
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Whoa! My teachers at art school never mentioned thatCareful with the plaster. You do not want to stick your hands in there to mix it. Plaster contains potassium sulfate, alum, borax, and lime, all of which are more or less toxic. Plaster contains also acetic acid, which is highly corrosive. When plaster hardens, there is an exotherm reaction, which can create enough heat to blow up a mould. Wear protective rubber gloves and goggles. Lime in the eye isn't fun.
I knew plaster had toxic elements, but I was taught to mix with my bare hands...I'll definately wear gloves next time (plus it is no fun to have to pick plaster off your arms). And as for that reaction during hardening - absolutely. Sometimes the mold can get quite hot!Yes, I do strip the hat down...pretty much following the guidlines that Fedora has graciously shared with us. I take the liner out, the sweatband out, and the ribbon off - gutting the hat. I then dunk the hat body into a large tub filled with hot water, and a little woolite. I swish it around in here for a while and then take it out and put it on the block while it is still wet. At this stage I try to stretch it over the block as far as it will go, and then I let it dry on the block. after a few days I pop it off, iron out the brim and put the hat back together - stitching in the sweatband is still my least favorite part. Then I have a clean hat which I can shape as desired. Sometimes I let the hat dry on the block in a hot car (which I know I shouldn't do) but it gives the brim a nice Raiders tension - I learned about this after my hat sat on the dashboard of my car during a midsummer, cross country road trip. When I put it on, it was a bit tighter (but it worked itself back out) and the brim had the most perfect swoop in it...a very nice tension through the brim that mimicked the Cairo look. That's about all I do to block a hat...JohnNdy, do you strip the fedora of the sweatband when you reblock?
-John