sealing wood press molds

[Stephen 531]

I'm carving a couple of  oak wood press molds this morning for prototyping a couple of tile designs. Will prob use them for about 10 presses and then I would like to hang on to them if I need them down the road after I make the plaster molds. I've used white wood for prototyping without any sealer or mold release and then tossing after a couple of uses but they are a bit rough by the time I toss them and I don't want these oak ones to warp since I might re-use in the future. 

I was going to hit them with a light urethane coat and let dry overnight before using. Is this a good idea or will it block the clay from releasing properly since the wood would then sealed and not absorb? 

[JohnnyK 685]

1 hour ago, Stephen said:

Will prob use them for about 10 presses and then I would like to hang on to them if I need them down the road after I make the plaster molds.

Sealing the oak will definitely stop absorption, but is that critical for press molds? If so, why not just make the plaster molds from the start?

[Stephen 531]

Hey thanks for the response, that's what I can't find in my search and worries me about sealing, Guess I will test by just sealing a few and leaving a few unsealed. It's in the 70's so going to let dry in sun and then press tonight so will know soon enough.   

[neilestrick 4,599]

Sealing them will definitely make the clay more likely to stick to them, but I get that sealing them will keep them from warping. If it won't affect your process after molding, you could use cooking spray to keep the clay from sticking to the sealed wood.

[Stephen 531]

Just bisque afterward so cooking spray would be fine. I have been using corn starch with the unsealed do you think the cooking spray would be better than the corn starch on the sealed oak? 

[neilestrick 4,599]

Try corn starch first. It's less messy.

[Pres 2,397]

When I made some molds using gesso and wood with a sealer over top, I used bakers spray to help release the pieces from the molds.

 

 

best,

Pres

[oldlady 2,802]

i have had a question for years about using cornstarch.   i know people use it but i never see exactly how it is done.   when i tried it, i ran into so many problems that there must be a simple way of spreading it evenly on whatever you put it on that i do not know.

my clay is very smooth, no grog,  the impression of a human hair can be seen on the work.   i want that quality so leaf edges and tiny veins transfer easily.    if i sprinkle cornstarch using a shaker i wind up with lumps that transfer to the finished piece.   

what is the actual procedure?  i am very happy using WD40 but just wonder how and why anyone would choose to use cornstarch.

[liambesaw 2,753]

6 minutes ago, oldlady said:

i have had a question for years about using cornstarch.   i know people use it but i never see exactly how it is done.   when i tried it, i ran into so many problems that there must be a simple way of spreading it evenly on whatever you put it on that i do not know.

my clay is very smooth, no grog,  the impression of a human hair can be seen on the work.   i want that quality so leaf edges and tiny veins transfer easily.    if i sprinkle cornstarch using a shaker i wind up with lumps that transfer to the finished piece.   

what is the actual procedure?  i am very happy using WD40 but just wonder how and why anyone would choose to use cornstarch.

I think you gotta load it up in a sock and then pounce it on 

[oldlady 2,802]

thanks, liam, that was what i was doing originally before i tried the shaker.   you still have not answered the real question, though.   are you putting it on the clay or the mold or what is the process that allows the work to separate from whatever but not be damaged by the starch?   maybe a video is what i need to see.

[Stephen 531]

14 minutes ago, oldlady said:

what is the actual procedure?  i am very happy using WD40 but just wonder how and why anyone would choose to use cornstarch.

I sprinkle in and dust it around a bit and then tap any loose residue out, works OK but do have issues with thin carvings not releasing well occasionally on wood. These have been prototypes until now that get trashed after a press or two and no products have been made with them. 

I worry about baking spray and/WD40 for pretty much the same reason as you (a large drop filling the corner or a design part) and the detail not being crisp.  This is my first attempt at trying to hang on to the wood prototype molds and use for a bit and even have some go through the work flow and become product. We'll see. 

 

Edited January 7, 2020 by Stephen

[oldlady 2,802]

stephan, i use wood a lot but not the way you are.  do you have any photos of the mold you are using?

[Stephen 531]

sure will grab a shot later. Just slump/press molds basically that you normally sell made out of plaster or ceramical sold commercially. I just prototype in wood first to dial it in.

[neilestrick 4,599]

Cooking spray should not affect details. I use it on stamps with lots of tiny detail and very small type.

[neilestrick 4,599]

20 hours ago, oldlady said:

thanks, liam, that was what i was doing originally before i tried the shaker.   you still have not answered the real question, though.   are you putting it on the clay or the mold or what is the process that allows the work to separate from whatever but not be damaged by the starch?   maybe a video is what i need to see.

You dust it on the clay and provides a dry layer that isn't sticky.

[Joy pots 41]

Hi,  I use corn starch on both the clay or a stamp or a press mold.  I apply it using a very soft fluffy brush.  I’ve also found the left over pieces of clay wedge back to reuse.

Joy

[Stephen 531]

OK pressed 10 of these after applying 3 coats of spray sealer and brushed in corn starch. That was 24 hours ago. Prob was way to light with the corn starch but not even close yesterday and only one released this morning after fussing with them with tapping and compressed air around edges. The sealer sat up a day and a half and was not tacky but prob barely cured. 

Going to re-press with cooking spray and compare the two. 

[liambesaw 2,753]

Could probably use silicone mold release spray instead and not get everything oily if you wanted to go that route.  We use that at work for deflasking plaster from brass

[Stephen 531]

On 1/10/2020 at 10:30 AM, liambesaw said:

Could probably use silicone mold release spray instead and not get everything oily if you wanted to go that route.  We use that at work for deflasking plaster from brass

Tried green soap as well. Once sealed the wood just won't release the clay. I brushed on green soap in 5 layers, drying in between and it still took a day to release and messed up the surface, Could keep experimenting but tired of messing with them. Only had 10 and I just tossed them in the trash. 

[liambesaw 2,753]

9 minutes ago, Stephen said:

Tried green soap as well. Once sealed the wood just won't release the clay. I brushed on green soap in 5 layers, drying in between and it still took a day to release and messed up the surface, Could keep experimenting but tired of messing with them. Only had 10 and I just tossed them in the trash. 

Sorry to hear that!