I am busy with restoration of premises and found that the putty in the window frames is about 20 years old. It is cracked and some sections have to be replaced completely. What product can I use to fill the small cracks that remain and require fixing? My local hardware store suggested acrylic sealer, but it is a water-based product and cannot be used because of the oil in the putty. I have used some new putty, but I cannot wait months to repaint the frames. Please help!
Chris Visagie, Witbank
This is a good and frequently asked question. I have experienced a similar problem and did not remove the putty – it wasn’t long before the cracks reappeared. So it’s definitely better to do it right the first time by replacing the brittle putty. The drying time creates security issues, which is generally everybody’s biggest concern.
A reader previously mentioned a product that can be added to the putty to speed up the drying process, but this particular product was frowned upon by one of the biggest manufacturers of putty in South Africa. Linseed oil should soften the putty, depending on how hard it has become, and the cracks should disappear.
Dr Andreas Landman from PG Building Products replies: Prevention is better than cure. After installing putty and waiting the required 17 odd days for the putty to set and having spent the money on painting the putty, you need to give the putty a maintenance coat from time to time. Our minimum recommended interval is 12 months, which should be shortened if the putty is exposed to excessive weathering.
Once a couple of layers of paint have been applied to the putty, a 12-month interval should suffice. This recommendation applies equally to varnished and enamel painted putty. With varnish the first two maintenance coats might be at three and six months, as the varnish layers tend to be relatively thin. An undercoat must be applied before applying the enamel layer
The fixing of cracked putty is not recommended, as re-glazing is better. The problem with putty going completely dry is that it cracks and no longer ‘breathes’ with the rest of the building. In the event that you really want to fix up old cracks, you should first remove any and all paint layers (hopefully after 20 years there are a couple of layers) and then dose the cracks with linseed oil. You will need to do this daily until the putty no longer absorbs new oil – known as the oil-drop test. Then allow the putty at least four days to set before painting. This is, of course, a risky route.
The drying time of putty is the subject of many discussions and is a compromise between allowing the putty to set quickly and not allowing the putty to dry completely, as mentioned previously. The line between putty going hard and putty cracking is very thin. For those interested in larger glazing jobs, there is contractor’s putty available. This putty usually needs to be mixed with a catalyst, which allows for faster drying times. Under no circumstances should putty be mixed with chemicals other than those provided by the supplier – paraffin, for example, is deadly to putty.
Remember, DIY putty that is available in most hardware stores is mixed with a catalyst that balances the need for shelf life, drying time and cracking. Adding the catalyst to the DIY product is therefore not recommended.
On the other hand, the contractor’s putty is mixed at the manufacturing plant without the catalyst and the contractor must add the catalyst to the putty. Contractor’s putty is available in 20kg and 40kg bags. A 20kg bag is usually sufficient to glaze a two bedroom house, whereas the convenient 500g packet is useful to replace the odd broken window pane.
EasiGlaze putty is available as both a DIY product and a contractor’s product and is SABS approved.
For more information, contact Dr Landman on 011-360-1000.
Glass bricks regulations
I would like replace my bathroom windows with glass bricks, but want to know if this is allowed by the South African building regulations?
I have steel window frames and every five years they start rusting and cracking the glass, so I would like to remove the windows and replace them with glass bricks. I have extraction fans installed and there are ventilation bricks in the walls.
Nico van Geuns, Cape Town
Clive Smith from Build Aid Consulting advises:
You may indeed remove the steel windows and replace them with glass bricks as long as there is adequate mechanical forced ventilation for the bathroom. The ventilation bricks in the wall will not count for natural ventilation.
I suggest that you contact your local municipality and explain the size and type of the mechanical ventilation in place at present just to confirm it is sufficient, but I am sure it is okay.
There is a company that will cut out the existing steel frame and replace it with either aluminium or wooden frames. This is great as it means you need not destroy the plaster reveals around the existing window frame. The cost of this window replacement system will more than likely be the same, if not cheaper than removing the old steel window, buying the glass bricks, replastering the reveals and soffits, and repainting the surrounding walls, not to mention the fact that you might have to retile the internal wall. What concerns me is why the glass cracks with the rusting of the steel window frames.
Brass window fittings
I need some advice on brass window fittings (painted white); how do you clean them and keep them clean?
Mike Sanders, Durban
Peter Sabatier from Glass & Brass suggests that you remove the brass window fittings and soak them in Nitromors. You can use a biodegradable stripper, such as Plascon RemovALL, but Nitromors works quickly and better on enamel paint. This is a dangerous product to work with so it is important to wear solvent-proof rubber gloves as long as possible, as well as protective eyewear, long sleeves and long pants so that you cover up as much of your body as possible – an overall works best.
Leave the fittings to soak for about five minutes; you will notice that paint will start to bubble and soften. Scrape off the remaining paint with a Stanley knife and, if necessary, use a small scraper to get into difficult corners. Wash the fittings in soapy water and dry. Then polish up with Autosol followed by a spray of Mr Min furniture polish, which prevents the brass from discolouring due to exposure to atmospheric conditions.
For more information, contact Peter on 011-454-3390.