feel free to ask questions/make comments/share your ideas.

note: all 'parts' by volume, not weight.

1 part boiled linseed oil. 6 parts portland cement, sifted. turpentine. quantity will depend on your desired mud thickness. concrete black. for black mud. quantity explained below.

  

what i use:

• 1 round plastic or steel bowl with lid. this is your mud keeper. • 1 cheap measuring cup set that will only be used to make the mud. use the kind that allow you to level off the ingredients at the top. • 1 bag grey portland cement. not concrete. there should be no rocks or sand in the bag. • 1 large rubbermaid container or other large container with sealing lid for the portland cement. you can leave it in the bag, but it's more convenient to use and store in a container with lid. • 1 similar container for plaster of paris. • plaster of paris. it's available in 25 pound bags, but smaller amounts will do. if you prefer using 'whiting' (calcium carbonate), then use that instead of plaster. • a cheap flour sifter. i made a small sifter screen from an old window screen and frame.  • a small box or quantity of black concrete coloring powder. also called 'carbon black' or 'lamp black'. it is available at some hardware stores, many building suppliers, and most concrete suppliers. one pound will go far. i store the stuff in a plastic coffee can, as it tends to rust out metal containers. the plastic container also keeps it dry. if you try a concrete supplier, bring your own container, as they tend to sell it loose by weight. • a plastic 'shoe box' to hold the plaster you will be using to clean the panels. • a second plastic 'shoe box' to measure out and sift the dry ingredients into, prior to dumping them into the mud bowl. • a small mixing paddle that fits into an electric drill. an old mixer beater works too. • a variable speed electric drill that will end up spackled with mud.   • 1 nylon bristle scrub brush with handle and a sealing tupperware type container the brush will fit in. when you are not using the brush, store it in the container with mineral spirits covering the bristles.  • a second nylon bristle scrub brush with a handle to help fix a potential problem i discuss below. • mineral spirits for clean up and brush storage. i also have some in a spray bottle. it's optional, but handy. • 3 'tampico' natural bristle scrub brushes to be used for the plaster brushing and final clean brushing. bristles should be around 1" to 1¼" long. number the brushes 1-3 with a sharpie.  • 1 bench brush to spread out your cleaning plaster, optional. • good dust mask or respirator. buy one that's worth your lungs and use it. • an apron. you don't want to appear as if you fell down in your work. • a handful of 1/4" oak dowel sticks cut in 10" or so lengths and sharpened on each end in a pencil sharpener. oak dowels last longer than pine. bamboo 'chop sticks' are my favorite and can be found in 'dollar stores', flea markets, and other outlets on the cheap.

the process:

 1) dump linseed oil into the round bowl mud keeper.
 2) put on your respirator and sift the cement into the linseed oil. add about 1/4 part turpentine to start, then a bit more as you mix until it is smooth enough to work with. mix the ingredients slowly, do not whip the stuff, just mix it gently. the consistency is that of thick pancake batter. some may like it stiffer, others looser. you will soon figure out your desired density after a few uses.
 3) if black mud is what you want, add 'concrete black' to the mix. to start, add a small teaspoon to a batch of mud. it goes a long way, so start light. you can always mix in more. the black mud gives a uniform dark gray pewter color to the lead and will offset your glass nicely.
 4) pour out the mud evenly along the lead lines and work the mud over the panel with the handled scrub brush. note: once this brush has been stored in the mineral spirits, remove it sometime prior to using it again, to allow time for the mineral spirits to drain away from the bristles before you use it, as it could thin out your mud too much.
 5) once the mud has been pushed into and around all the leading to your satisfaction, scrub up as much excess mud as you can, squishing the excess back into the mud container.
 6) put on your respirator and cover the panel with a cup or two of plaster of paris and scrub it with the first (#1) tampico scrub brush. work it like the mud dog you are, removing as much mud as you can from the glass and around the lead. work it with the lead, against the lead, and in circles. woof! the plaster will help set the mud and start the drying process. brush off the plaster into it's plastic 'shoe box'.
 7) flip the panel and repeat steps 4 - 6.
 8) spread out some plaster evenly across the panel side showing.
 9) i usually leave the panel sit for 4-5 hours covered with the plaster until the mud has calmed down and stiffens up some. if it's hot out, the mud sets faster, so keep your eye on it. adversely, cooler temps need more time.
 10) brush off the plaster into the plastic 'shoe box' again and take a sharpened dowel stick and run it along the lead, around each piece of glass in the panel. is the mud still too loose? if so, let it sit a few hours more and try doweling again. 
 11) once you sticked each piece, vacuum or blow off the resulting debris. i always do my mudding outside and blow away the debris with compressed air. doing your mud work indoors is a very dusty and messy job. you could set up a temporary mud table on saw horses outside. note: beware of circumstances where rain can ruin your day. plaster and water make bad partners when mudding stained glass panels. the clean-up is a nightmare. never allow the plaster to get wet.  
 12) take the second (#2) cleaning brush and scrub it clean. use the sharpened dowels to go around the panel a second time.
 13) once the panel is doweled well, use the second (#2) brush again for your end brushing. pick out and brush errant mud left behind.
 14) flip the panel and repeat steps 10 - 13.
 15) use the third (#3) brush the next day to polish up the panel and lead work. inspect for lingering mud outside the lead lines. your lead should have a nice shine and a dark gray patina with no mud seeping out from under the lead crown. try to allow 3-4 days for the mud to harden prior to installation, especially in active doors and also if your panel includes ⅜" or wider lead. you might indicate to clients that there may be a lingering aroma of turpentine for a short period of time.

i found these two mud bowls as a set at a 'dollar store'. if you find such a deal, stock up.

about the mud keeper: in order to insure a tight seal with your bowl and lid, try to keep the rim and lid as clean as you can. wiping with a paper towel dipped in mineral spirits usually does the trick. i use an old tablespoon and butter knife to scrape out old mud that has hardened up.

about the tampico scrub brushes: these are also known as 'acid' brushes. they have a natural bristle (not plastic, nylon, 'tampico like', poly, or other synthetic). they can be found at many hardware stores and have bristles about 1" or so in length. over time, your brushes will get crudded up with mud build-up and the bristles will wear down. rotate your brushes so the dirtiest brush (#1) is always used as the first cleaning brush. at some point, throw away your oldest, most abused brush when it no longer seems to be doing what it should. move the next dirtiest (#2) up to take it's place. you always want to have the best brush (#3) as your last cleaning brush.
   i know i'm going on and on about these brushes, but the secret to a good mud job and a clean panel is using your brushes correctly and enough. you will soon see that the time you spend brushing, will save you more time over having to tediously pick at hardened mud that could have been easily brushed clean while the mud was still pliable. it is doubtful you can over brush a panel. never use your brushes for anything other than this process.
   i buy tampico brushes on ebay in bulk and give them to clients for the occasional cleaning of their panels after installation. often there's an ebay deal selling them by the dozen. check every now and then, as they should not cost you more than $3 or so each. if you find a seller with a quantity at a good price, inquire about a combined shipping discount, if it's not offered.

tampico natural bristle 'acid' brush. bristles are about 1" to 1¼" in length. nylon mud brush usually found at the 'dollar store'.

the safe use of the product: you are expected to read and follow all written safety instructions on every product ingredient you purchase in the making and use of this cement. proper respirators, gloves, body, and eye protection are your responsibility and i highly recommend you use them. linseed oil and turpentine are flammable, do not use or store near fire or flame. the cement and it's ingredients are an irritant to skin and eyes. avoid skin contact. avoid inhaling vapors or dust. use only in a well ventilated area. you are to insure the safety of yourself and anyone or any thing that may come into contact with the product or ingredients. this includes children and pets. do not eat, drink, or smoke when using the cement or any of the ingredients. properly dispose of refuse and materials in a safe and environmentally friendly manner. your use of the product and ingredients is beyond my control and i assume no responsibility for your actions and/or misapplication of this stained glass cement product. let common sense prevail.

the safe storage of the product and ingredients: be sure that random debris does not contaminate your ingredients. introducing glass chips while you cut out a project, can lead to disastrous scratches on your panels. that's why i use covered containers to store my dry ingredients. cement left in the bag can harden up over time due to humidity or standing in water. keep all ingredients out of reach of children and pets and anyone else unfamiliar with them. store finished product and liquid ingredients in a cool place. do not let the cement product freeze.