For straight casting it may be better to just use the epoxy and forget about all of the plaster and cement. I could cast the top layer first with clear epoxy, then paint in the back with the cement images in reverse order and don't use any cement or plaster. The reason that this won't work is that epoxy seems to need something to hold onto and it may change shape and become fluid in heat, therefore as a thin layer epoxy is good as a coating, but not so good structurally and something strong under it is best, whether it is wood, plaster or cement. Plus the epoxy would require painting in reverse order and that would just take away from the fun of making these pieces as I have been developing my techniques and in some cases I don't even have to paint my finished work, like with the cast brick wall patterns in the screen printing frames.
Painting can be considered a final coat, instead of an epoxy layer. In many cases I am spray painting color and added effects like brick lines by spray painting onto the cast materials like the Duracal gypsum plaster cement. The paint, if it is bonded well, is essentially a sealant, a top layer of protection from UV and rain, but I don't fully trust it. Mostly because paint scratches easily and will rapidly wear away with weathering, as can be seen on the many murals around Los Angeles. So except in mild conditions or for short periods of time, spray painting is not a satisfactory sealant by itself. I have used spray painted clear coats on top of epoxy, but the smell and blurriness that ensues is not worth it.
Double sealing by coating the back and the front is not to be done. If I have learned anything it is not to completely seal anything. If you do then the moisture that is built up inside with eventually destroy an item from the inside, so I have resisted the desire to paint the back of my pieces or to add an extra layer to the back, unless I leave the front unsealed. Ideally, my pieces are not completely sealed in that the wood on the edges can absorb moisture, but how would the water know to migrate to that part of the frame? Possibly the capillary action of the wood could draw the water from the plaster over time and work as a sponge, but I don't feel comfortable with this for now, although it is intriguing.
The wooden frames are serving as bumpers for the castings and in the past I have had trouble with the piece drying out and dropping from the frames. However, I have since worked in reinforcement and anchors regularly to keep this from happening. I broke apart one piece the other day and first off I was able to walk on it without it breaking and secondly with I tried to break the individual piece it literally broke the wire mesh inside instead of separating along any specific line. Therefore the reinforcement with plasters should make the pieces hold into the frames for years, or until the wood itself rots away. I am no longer putting decorative top frames on my pieces as they tend to get broken in transport and now that I am anchoring the pieces more successfully I don't think the top frames are needed to act as a bonding agent or washer against the wood.
I have been testing aluminum frames, but I have so many wooden frames in storage I still consider this testing and a future application. I have to keep going forward with using up the thousand or so wooden frames I have in storage to escape the trap I have created for myself by doing so much commercial work with screen printing over the years. In a way this is my punishment for being successful as a business person in that I have built up an archive of old frames with screen printing designs on them and most of my efforts with photo fresco prints has been to find an application that can use up these frames. Now I am buying aluminum frames for my screen printing, but I still need to recycle these frames instead of just taking them to the dump, cleaning them out and reusing them or continuing to pay rent for them in a storage unit in the desert. The wall is the best use I've come up with so far, although then I am going to have to store the wall, but hopefully I can build a house or fence out of the wall and then just watch it wear away over time.
Thursday, July 21, 2011
Gypsum Plaster Products versus Portland Cement Products
Without getting into the chemistry about why one of these types of products is better than the other I have just started testing them in my pieces to see which ones I like. Personally I am overwhelmed by the many different types of cements that are available at my local hardware stores, not to mention the mortar isles, I haven't even been able to start in that section. Truly I don't know the difference between mortar and cement, other than one must be made for adhesion and the other for durability and strength. The mixtures between portland cement, sand and additives seems to largely make up the differences between the materials. Price is my concern and the ability of the cements to make detail in a mold, so I haven't found many workable solutions that include any type of aggregate when it comes to the portland cement products. Mortar has no aggregate, but the cracking when it is poured at 1/2" or more increases, so I have decided to stay away from the mortars for now.
The biggest problem with portland cement based products verus the plaster gypsum based products is shrinkage. Cement shrinks, even the expensive stuff. I've been working with "Cement All" at $18 for a 55 lb. bag and although the cracking is down to a minimum, it still appears to shrink around the edges. I have anchored the pieces before I pour the Cement All mixture, as well, I have put in a reinforced wire mesh to strengthen the casting, but I don't want to have to rely on the mesh and anchors as a way to keep my pieces in place and even with an epoxy coating on top to help with the bonding, I find myself back to square one which is why use durable materials if I have to seal them in a clear bullet-proof case to make them work?
Ideally the concrete may get it's strength from the shrinkage as the water is displaced and the molecules harden into durable structures that can exist outside in the elements. Also the strength may allow the material itself to resist cracking in normal temperature fluctuations, so there are some good factors about portland based cement products that have kept me from giving up. Stucco was another material that I have been playing with, but as I use it more and more I don't see really the advantage of it over other acrylic polymer based gypsum based products and I don't seem to get the detail out of the stucco that I do with the plasters. I have also forgot to mention the setting times are longer with the cements, even the quick ones, as compared to the plasters.
This brings me back to the Gypsum plaster based products and the one that seems to work like cement, but expands like plaster is Duracal. Grey in color I have mixed it with red cement powder and have gotten a nice brick color. Duracal seems to be strong and sets very quickly, unlike the cements. The detail when casting with the Duracal is as good as with the other plasters like Hydrocal, Forton MG and Tufstone. Tufstone is my favorite white based plaster that has microfibers mixed in and an acrylic polymer, but neither of these items may be as durable as cement without coating them and covering them with sealants.
Having completed my first Wall of Photo Fresco pieces, as shown in a prior post, I realize that weight may be a larger factor than strength. The pieces I have been making with the cement were made with the idea of being about to be placed in the ground, like bricks for a walkway, only with images molded and cast into them. I took these same items that can hardly be picked up and used them as a the pieces in my photo fresco wall and the weight of the wall scares me. I can see this think falling over and killing me as some sort of artistic justice in that I keep trying to make something that will last a long time, so it inadvertently shortens my lifespan proportionately. Now I live in fear of my wall as I have tied it to the strongest thing in my yard, and unused weight lifting device that is too heavy to get rid of. I may not lift weights, but lifting and moving these photo fresco castings all day is indeed a workout.
The weight of the wall is something that I must deal with and this seems to lead to the obvious conclusion that the thickness must be reduced. I spoke with an engineer about how thick concrete needs to be to be able to be walked on and 2 1/2 inches is a basic measure, so I have been back filling these castings with thicker layers of aggregate based cement to give them the option of being able to be used as counter tops on tables or a walking bricks, sort of like the Hollywood stars in LA, but my style. This added weight also means more material, which in the end offsets any savings that come from the cheaper Portland cement based products. Unless I can find a cement that does not shrink and is truly crack resistant then I need to go back to the high tech plasters, like Duracal and make thinner walls that weigh less once they are made.
My son has finally found a practical use for this wall as he thinks that he can use the wall as a practice board for throwing lacrosse balls at, well, this may not work with the thinner structures, but if the wall can withstand that type of abuse then I can use that as a measure of success. At least as he propels the rubbery heavy balls to the wall he won't be standing under it, so the risk of the wall falling on him is less. Still I don't trust the weight and I can't see any way to make the photo fresco wall without using lighter materials, even if they require additional exterior coats to make them durable and resistant to the elements.
The biggest problem with portland cement based products verus the plaster gypsum based products is shrinkage. Cement shrinks, even the expensive stuff. I've been working with "Cement All" at $18 for a 55 lb. bag and although the cracking is down to a minimum, it still appears to shrink around the edges. I have anchored the pieces before I pour the Cement All mixture, as well, I have put in a reinforced wire mesh to strengthen the casting, but I don't want to have to rely on the mesh and anchors as a way to keep my pieces in place and even with an epoxy coating on top to help with the bonding, I find myself back to square one which is why use durable materials if I have to seal them in a clear bullet-proof case to make them work?
Ideally the concrete may get it's strength from the shrinkage as the water is displaced and the molecules harden into durable structures that can exist outside in the elements. Also the strength may allow the material itself to resist cracking in normal temperature fluctuations, so there are some good factors about portland based cement products that have kept me from giving up. Stucco was another material that I have been playing with, but as I use it more and more I don't see really the advantage of it over other acrylic polymer based gypsum based products and I don't seem to get the detail out of the stucco that I do with the plasters. I have also forgot to mention the setting times are longer with the cements, even the quick ones, as compared to the plasters.
This brings me back to the Gypsum plaster based products and the one that seems to work like cement, but expands like plaster is Duracal. Grey in color I have mixed it with red cement powder and have gotten a nice brick color. Duracal seems to be strong and sets very quickly, unlike the cements. The detail when casting with the Duracal is as good as with the other plasters like Hydrocal, Forton MG and Tufstone. Tufstone is my favorite white based plaster that has microfibers mixed in and an acrylic polymer, but neither of these items may be as durable as cement without coating them and covering them with sealants.
Having completed my first Wall of Photo Fresco pieces, as shown in a prior post, I realize that weight may be a larger factor than strength. The pieces I have been making with the cement were made with the idea of being about to be placed in the ground, like bricks for a walkway, only with images molded and cast into them. I took these same items that can hardly be picked up and used them as a the pieces in my photo fresco wall and the weight of the wall scares me. I can see this think falling over and killing me as some sort of artistic justice in that I keep trying to make something that will last a long time, so it inadvertently shortens my lifespan proportionately. Now I live in fear of my wall as I have tied it to the strongest thing in my yard, and unused weight lifting device that is too heavy to get rid of. I may not lift weights, but lifting and moving these photo fresco castings all day is indeed a workout.
The weight of the wall is something that I must deal with and this seems to lead to the obvious conclusion that the thickness must be reduced. I spoke with an engineer about how thick concrete needs to be to be able to be walked on and 2 1/2 inches is a basic measure, so I have been back filling these castings with thicker layers of aggregate based cement to give them the option of being able to be used as counter tops on tables or a walking bricks, sort of like the Hollywood stars in LA, but my style. This added weight also means more material, which in the end offsets any savings that come from the cheaper Portland cement based products. Unless I can find a cement that does not shrink and is truly crack resistant then I need to go back to the high tech plasters, like Duracal and make thinner walls that weigh less once they are made.
My son has finally found a practical use for this wall as he thinks that he can use the wall as a practice board for throwing lacrosse balls at, well, this may not work with the thinner structures, but if the wall can withstand that type of abuse then I can use that as a measure of success. At least as he propels the rubbery heavy balls to the wall he won't be standing under it, so the risk of the wall falling on him is less. Still I don't trust the weight and I can't see any way to make the photo fresco wall without using lighter materials, even if they require additional exterior coats to make them durable and resistant to the elements.
Long Time No Plast ...er that is.
I haven't been posting regularly about my progress and work with casting reliefs, screen painting and photo fresco works as I keep testing new materials and until now I have been too caught up in the work to report to headquarters. As a result I will post a bunch of material in short burst with some accompanying photos, not in any particular order. My latest experiments have been with using cheaper materials like Portland Cement based mortar, stucco and cements to try increase the waterproof character of my pieces.
Water resistant, water proof and ultimate durability go hand in hand. The most toxic element in regular outside exposure is water, through mist, fog, rain, and basic humidity. Temperature change is also an invisible factor that changes the shape of items throughout a day. Strength within an item may resist the shape-shifting, but the porosity of an item also allows saturation which in turn may cause materials to breakdown. Sealing a piece is also a way to stop water from getting into an item, but my understanding is the if an item is completely sealed temperature changes will still make the materials that are used increase and decrease in size throughout a range and this is what can cause materials to crack and break away from each other.
I have been using Epoxy instead of Polyester resins in many situations when it comes to sealing the top side of my photo fresco pieces. The epoxy may expand and contract more easily than the stiffer polyester resins, although the resins may bond and seep into spaces better. The setting time for the polyester is shorter, but the smells are more annoying. I prefer the polyester resins to the epoxy when it comes to casting detail and strength, but I think when it comes to sealing an outside piece the epoxy, without any layers of resin works best. The thickness of the clear epoxy layer also seems to work like a clear plywood that bonds the exterior edges.
It takes a long time for the epoxy to set up and the air bubbles are problematic, as well as, bugs, debris of any kind and paint brush hairs. Everything will show up in the end. However, with the epoxy I can use the final layer as a part of the structure and reduce the depth that is required for strength. However, the protection against Ultra Violet radiation, UV, is limited with Epoxy and I have gotten yellowing very quickly once I have exposed my pieces to daylight.
I found that the epoxy seems to bond well to portland based cement products and gypsum based plaster products, considering that both of these are porous on the surface and the epoxy has a long set time that allow is to migrate into any crevice that may help with bonding. By using epoxy on the cement and plaster castings I have now had to put a final varnish cost to protect from UV exposure. To me this is the weakest link and requires additional work with drying time, blurring and the basic problems that come with varnishing. I have heard that there may be some kicker that can be added to epoxy to increase or add UV protection to epoxy, but I haven't work with spending more money on that yet.
Assuming that epoxy and clear coating varnishes don't add anything other than new layers of invisible protection and exterior strength to a piece I have gone backwards to find more durable products that don't require coating to exist for a long time outside. This brings me to my next issue about Gypsum Plaster versus Portland Cement.
Water resistant, water proof and ultimate durability go hand in hand. The most toxic element in regular outside exposure is water, through mist, fog, rain, and basic humidity. Temperature change is also an invisible factor that changes the shape of items throughout a day. Strength within an item may resist the shape-shifting, but the porosity of an item also allows saturation which in turn may cause materials to breakdown. Sealing a piece is also a way to stop water from getting into an item, but my understanding is the if an item is completely sealed temperature changes will still make the materials that are used increase and decrease in size throughout a range and this is what can cause materials to crack and break away from each other.
I have been using Epoxy instead of Polyester resins in many situations when it comes to sealing the top side of my photo fresco pieces. The epoxy may expand and contract more easily than the stiffer polyester resins, although the resins may bond and seep into spaces better. The setting time for the polyester is shorter, but the smells are more annoying. I prefer the polyester resins to the epoxy when it comes to casting detail and strength, but I think when it comes to sealing an outside piece the epoxy, without any layers of resin works best. The thickness of the clear epoxy layer also seems to work like a clear plywood that bonds the exterior edges.
It takes a long time for the epoxy to set up and the air bubbles are problematic, as well as, bugs, debris of any kind and paint brush hairs. Everything will show up in the end. However, with the epoxy I can use the final layer as a part of the structure and reduce the depth that is required for strength. However, the protection against Ultra Violet radiation, UV, is limited with Epoxy and I have gotten yellowing very quickly once I have exposed my pieces to daylight.
I found that the epoxy seems to bond well to portland based cement products and gypsum based plaster products, considering that both of these are porous on the surface and the epoxy has a long set time that allow is to migrate into any crevice that may help with bonding. By using epoxy on the cement and plaster castings I have now had to put a final varnish cost to protect from UV exposure. To me this is the weakest link and requires additional work with drying time, blurring and the basic problems that come with varnishing. I have heard that there may be some kicker that can be added to epoxy to increase or add UV protection to epoxy, but I haven't work with spending more money on that yet.
Assuming that epoxy and clear coating varnishes don't add anything other than new layers of invisible protection and exterior strength to a piece I have gone backwards to find more durable products that don't require coating to exist for a long time outside. This brings me to my next issue about Gypsum Plaster versus Portland Cement.
Wednesday, July 20, 2011
It is a wall of bricks - photo fresco style
I just keep making these things and now finally I have a place to put them, on a wall. I've made tables out of these brick frames, cemented them in the ground for walking stones and now I've mounted a batch of them onto a wooden frame for an interchangable photo-fresco brick wall. This is sort of like one of those games that has pieces that can be moved around only a lot heavier. This wall is self supporting, although I have not tested it in a heavy wind, and is approximately 8 feet tall and almost 6 feet wide. It has a vertical and two horizontal columns of frames that can slide in and out from the back. I have had the idea for a long time and even applied it earlier to screen painted frames, but it did not seem as awesome as this, which is why I probably kept working to make this thing. I'm not sure where it is going to go, or what I am going to do with it, but for now it is done. Ta da!
I may have to dismantle this wall and take it to Los Angeles. I don't really have a any type of art gallery to show my work, but I do have a store in LA called Y-Que Trading Post. Periodically I take my individual pieces, usually in sets of new work and switch out the pieces in the front window. These new pieces are very heavy as I have made them to also serve as walking stones or table tops. There is not rhyme or reason for the layout or composition of the current wall, but I did try to find some symmetry between the images and I enjoy the vertical strand in the middle. The chicken images and the black bricks both have 4 pieces shown and each piece is somewhat representative of different materials and techniques as I have progressed along while using my old screen printing frames as the wooden base to cast these faux brick patterns in. There is a street fair in the Los Feliz neighborhood this weekend so it may be a good time to get down there and put something interesting in the store. Driving has been a real problem these days due to gas prices, but I don't see any benefit to sitting in may backyard and staring at this wall for months on end, which means, "ROAD TRIP!"
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