Friday, 19 November 2010

Gardening ~ birdbaths and an experiment with hypertufa

I must begin by saying that my experiments with this are as yet incomplete.  I relate them here to encourage readers to consider experimenting with hypertufa as it's fun, ingredients are relatively cheap and it opens up a range of possibilities for garden ornamentation. 

Hypertufa first came up as a possibility when I was wondering how to make a birdbath since I couldn't afford to buy one and 'hypertufa' was suggested.  Please note that the Wikipedia link provided includes not only a definition but also some useful web links.

Searching on 5 I found the video clip below which gives very helpful information, not about bird baths but about making plant pots which was enough to get me started.  They make it look straightforward and enjoyable which it is.

I include the direct link to the video as posted at the 5 minute site as well in case you want to browse around the site.

Here is a WikiHow article based on this same video if you want to look at the content slowly step by step

The ingredients are Portland cement, peat moss, perlite and water.  Of these perlite is the most costly, but the sum of the ingredients was vastly cheaper than buying anything I might make with it ready-made.

Perlite isn't all that commonly known or stocked in New Zealand hardware or gardening shops, but a 'proper' gardening shop did have a supply as it's used in hydroponics as a root bed.  It's also used in some concrete slab construction.  It looks and behaves very like polystyrene, so open your bag in a draught-free spot!  It is a naturally occurring substance however.  I used the contents of a five litre bag and could have done with about half of another one given the size of what I was making.

My birdbath worked out well.  Being new to the technique and unsure of how to best work out the details of my mould I put off getting on with it for some weeks.  I ended up breaking through what I call perfection paralysis by deciding that it didn't greatly matter if it didn't work out and if that was the case experimentation should eventually lead to success.  I also decided that simplest was best!  Here are some photos I took during the process:

A dis-used glass lampshade I got second hand for five dollars was the exact size and shape I wanted:

I covered the glass first with glad wrap and then with aluminium foil to keep it stain-free.  I then covered the garage bench with builders plastic to keep it clean and dry and set up my mould face down on it.  The plastic also gave me something to draw on!  The pen marks and rolled circle of aluminium foil were to help with getting the rim where and how I wanted it. 

Mixing up the brew was straightforward.  I was glad to be doing it in a well-ventilated space due to the cement dust:

You can see it below all packed on to dry.  I realised too late that I hadn't anchored my mould to the plastic so it shifted a bit making it slightly uneven as you can see!  The edging was made out of a strip of heavy cardboard.
     The suggested thickness is one to two inches.  I measured the depth of coverage with a skewer stick which had a piece of tape fixed around it to mark a depth of one inch and then smoothed over the holes.  In retrospect it would have been better if I'd made it nice and chunky with a thickness of two inches.  To do that I would have needed twice as much of the mixture and a higher edging.

The drying time is seven days.  After a week had passed  I carefully unwrapped it, fearful it might fall to pieces.  It didn't, but what I didn't expect was that the foil disintegrated, presumably in reaction to the lime in the cement.  Having vacuumed it carefully I had to scratch the last bits of it out of the finished form with pointy skewer sticks.

The rim did turn out to be somewhat lopsided, but I decided I liked it!

I learnt three significant things from my efforts:
     The first is that the birdbath is somewhat porous.   I should have expected this as the instructions do mention it.  This makes it ideal for outdoor planters, but unsuitable for a birdbath unless it's sealed.  Without this it needs to be topped up each day.  I realised I needed to paint it with some kind of sealant.
     The second was that I became concerned that the unsealed cement might make the water a little toxic which was another reason to seal the surface.  I'm still not clear  as to whether or not a degree of toxicity is an issue but consider it best to settle for painting it - with something non-toxic(!) - to be on the safe side.
     My third realisation was that it was, wait for it, too deep for the birds.  It was perfect for a fairly large bird to get right into for a good splash as one blackbird did, but the rim was too smooth and the water too deep for birds to perch on the rim and bend in.  The simple solution to this last issue would have been to place rocks and possibly sticks in it, but essentially it was still a design fault.  So I did learn a lot. 

However, I enjoyed it just as it was for a few weeks before it suffered a disaster - Rewi tripped when turning and landed on it.  It broke.  Oh dear!  Just as well it was the birdbath and not him.  I have yet to attempt to repair it.  When I do, I'll ask at the hardware shop about suitable sealants and paint it some pleasantly subtle colour.  It seems a pity to have to paint it though, as I like it's rough finish and stony appearance.  Even if repair is successful I expect to make another one as it's fun. 

When I take my experiments further I'll add to what I've written here and note that I have done so on my Updates page.

Later note about sealants:
I have yet to continue with this project.  I have however, purchased the sealant necessary to make it watertight once I've finished other work on it.  Staff at Mitre 10 were characteristically helpful, and recommended Micara PondPaint, described on the label as "elastomeric waterproofing membrane: tough flexible coating, UV stable" and designed for "water features, fishponds, birdbaths, concrete, etc."  You do not need paint as well.  I'm delighted about this as I very much like the the look and texture of the hypertufa.  This part of creating your birdbath is not for the hasty, as the object has to be left to cure for a minimum of four weeks before sealant is applied.  The smallest pot contains a whole litre and is relatively costly, so look forward to using it on an array of hypertufa objects, which I'm sure you'll enjoy creating, or consider sharing a pot with others doing similar projects.  In saying so I'm setting myself an agreeable challenge!
P.S. I love Mitre 10 shops I pass on the Mega versions which are more like hardware supermarkets, but love the local ones in which staff actually know their products and provide first rate service.


Anonymous said...

That is awesome! I love that you told us all the problems and challenges that went along with the process. Very helpful for my tufa attempts.

Leigh Christina Russell said...

Thank you, and I hope you enjoy making your own! I have yet to get around to having a second go at it, and look forward to doing so - one day when things have *settled down*.

Jen said...

WOW What a great post. Thanks so much! I am about to embark on some Tufa projects - a large, shallow water dish; very similar to yours, for my new Japanese garden and I'd also like to have a go at making some large landscaping rocks ... YIKES.

Leigh Christina Russell said...

Hello there Jen, thank you for your comment, and all the best with your hypertufa projects.

It has since been suggested to me that I could have made the birdbath right side up - directly into the ground with perhaps a plastic sheet underneath it.

I was pleased to visit your site and am very impressed by your knitting projects, and the kindness you show your friends - they are fortunate to know you.

Your knitting reminded me of the blog site Boroque purls, also by a New Zealander, which you might enjoy. I've forgotten how to make a link in the comment field, but here is the address in case you are interested:
Best wishes,