MY PLASTER PULP EXPERIMENTS CONTINUED - A NEW VERSION IS A FAILURE!

First of all i am going to break this away from my 'something for my Etsy store' feature postings and run it from where my last plaster pulp experiment posts left off.

Secondly the title is not quite accurate. The 'new' plaster pulp recipe whilst not being a total success that i was hoping for didn't throw up any new problems. Well beyond human error, okay stupidity. I am not afraid to admit to making mistakes after all. To clarify the mistakes i did not measure of the ingredients for the last two new pulp batches accurately. I simply 'spooned' and guessed the quantities involved. Stupid stupid armature way of doing things i know, i know but there you have it. Moving on then.

My first plaster pulp experiments using ClayCrete a commercially purchased ready prepared mixed pulp were a total success. I forget how much amount wise you get per bag a couple of pounds or so at £10.00 GBP, Not a lot if your making large or numerous projects. However not knowing what the binding agent is in the commercially purchased product leaves me stuck in re-creating the same results it gives with home made recipes - for now at least.

My home made pulps for use in my other earlier plaster pulp experiments were a success also in that they formed perfectly in the moulds copying the details of the moulds & were near enough strength wise to both suit my needs and being close enough to the commercial pulp. How ever as i have said the 'core' of the casts i made using my home made pulps were not bonding with the plaster enough to make them viable.

My new plaster pulp recipe has the exact same flaws, though my armature method of mixing this plaster pulp version if nothing else not only confirmed my previous theories but also reinforced them. I want the mix to be as close to 50% plaster and 50% paper pulp as possible keeping it in the acceptable standard PM constraints and allowing it to be rightfully classified as a paper mache product. So my theories, discoveries and conclusions so far then.

WHITE MATTER Ver. 1 ©TM J Jones

POSITIVE POINTS (Air and radiator drying)

Created using commercial ready made pulp: 100% success. extremely Light weight, strong throughout, fast drying. Can be carved/sculpted using sharp tools.

NEGATIVE POINTS

The commercially purchased ready made pulp IS expensive and comes in small amounts.

GREY MATTER Ver. 1 ©TM J Jones

POSITIVE POINTS (Air and radiator drying)

Created using home made news paper based pulp 70% success, extremely light weight.

NEGATIVE POINTS

Soft inner core: Plaster and pulp not bonding leaving it susceptible to breaking easily.

GREY MATTER Ver. 2 ©TM J Jones

POSITIVE POINTS (air and radiator drying)

Created using home made news paper based pulp 50% success, extremely light weight, strong outer shell finish, fast drying. Can be carved/sculpted using sharp tools if some what cautiously.

NEGATIVE POINTS

Soft inner core: Plaster and pulp not bonding leaving it susceptible to breaking much more easily.

GREY MATTER Ver. 3 ©TM J Jones

POSITIVE POINTS (Air and radiator drying)

Created using home made news paper based pulp 40%/50% success, extremely light weight, strong outer shell finish, fast drying. Can be carved/sculpted using sharp tools if somewhat cautiously.

NEGATIVE POINTS

Soft inner core. Plaster and pulp not bonding leaving it susceptible to breaking much more easily again.

WHITE MATTER Ver. 2 ©TM J Jones

POSITIVE POINTS (Air drying)

Created using home made toilet roll tissue paper based pulp 20%/30% success. If plaster 70% to pulp 30% ratio. Extremely light weight, moderately strong outer shell finish, fast drying depending on water content. Can be carved/sculpted using sharp tools with care.

NEGATIVE POINTS (Radiator drying)

Too much water: Can take 48+ hours to air dry. Extremely difficult to work with even in a mould. Soft throughout surface to inner core with a soft outer paper like pulp like shell. Plaster and pulp not bonding, Shrinkage EXTREME. Cracking and crumbling when handled.

Too much pulp: Dries too slowly, Soft throughout surface to inner core with a soft outer paper like pulp like shell. Plaster and pulp not bonding. Shrinkage EXTREME. Crumbles when handling.

Too much plaster: Dries too quickly, medium hard surface and core. Plaster and pulp slightly better bonding. Shrinkage varies. Crumbles when handling though slightly less so.

THEORIES AND CONCLUSIONS

With exception to the water, pulp and plaster ratios the 'same' main problems as in the original home made pulp versions. The plaster and pulp not bonding sufficiently enough. Adding raw linseed oil contrary to positive research had NO noticeable effect in ANY positive way. Indeed giving pre-made plaster moulds two coats did not strengthen the already hard dried plaster. In fact they became softer. Before painting on two coats of linseed oil the plaster moulds had an extremely hard ceramic like surface that i could not mark with my fingernail and have to when required carve/sculpt with a craft knife. After coating in linseed oil and leaving twenty four hours to dry out i could easily scratch the surface and a little deeper with my thumb nail.

Using toilet roll tissue instead of news paper pulp did make mixing the 'wet' pulp and plaster much easier, so a positive point there. However my original recipes are based on 'dried' pulp ratios. The wet tissue pulp offers up it's own problems in calculating the weight to content ratios for a more accurate recipe since water content of the tissue pulp can and will alter from batch to batch. Something to ponder there for sure.

Substituting the original news paper pulp for the tissue pulp HAS positive advantages i am in no doubt. Certainly in mixing and dry weight, probably even in account of strength too. The problem remains constant however when it comes to achieving a bond in the core of the mix when dry. I have a 'potential' solution in mind, but this brings with it its own potential problems too.

PVA glue (Elmer’s etc) or more specifically the type/brand i use is well known for its bonding properties. Indeed its used widely in the building trade when plastering old dry walls where old traditional lime based plaster would have once been. A coat of watered down PVA glue directly on the wall allows the new modern plaster to bond to the old stone work. So theoretically it 'may' make the plaster bond to the paper pulp in this case?

The potential problems then being PVA glue(s) and liquid latex moulding solutions have one key ingredient 'latex'. It has to be assumed of course that it may vary in amounts andstrengths in each product i know from experience that a torn latex mould can be repaired if torn etc with pure PVA glue, ie: They bond readily and strongly!. So now the question is how much is going to be enough to create a 'potential' bond between the plaster and the tissue pulp without being too much and bonding with the latex mould?

Another thing to consider here of course is joint compounds. Of which there are many versions and again like the linseed oil joint compounds have received a lot of positive press. Of course there remains a singular issue throughout the whole of this experiment that cannot be ignored. We all be we in different counties or countries have different grades of papers, glues and compounds be they joint, latex or wood based. What work for one person in one region may not work for another elsewhere?

At the very least i can hope for is gaining the right working recipe that suits my needs that other 'may' be able to use too or at best if not a working recipe for others then a starting point that they can use to find the solution for themselves in this area at least. Below you can see my most recent attempts and failures.

Here the problem was not enough plaster in the mix.

 

The experimenting continues.

More soon.