Dunlop Fibre Cement Jointing Compound sanding timeframe?

[Davy]

Hi there,

I applied the dunlop Fibre Cement Jointing Compound onto blueboard last night and won't be able to sand it off until Friday will that make it harder to sand smoothly?

What is the recommended time frame to sand it off? I read on the container to allow 4hrs  before sanding is there a maximum time when it will be difficult to sand. And l baked it on heaps oops 

 

Many thanks

Dunlop 3kg Fibre Cement Jointing Compound 

[JacobZ]

Hi @Davy,

Thank you for your question and welcome to the Bunnings Workshop community, it is fantastic to have you with us.

The Dunlop Fibre Cement Jointing Compound is intended for use as a base coat as opposed to a topcoat. This means that it sets extremely hard to create strength at the joints. For this reason, regardless of the time frame that you leave it, you will likely have considerable trouble trying to sand it to a smooth finish.

My suggestion is to scrape and sand away any hard edges and then apply a wider coat of James Hardie Compound Top Coat over the top of the jointing compound. This is a topcoat designed for use with fibre cement, so it is much lighter, smoother and easier to sand. 

Let me know what you think and if you have any other questions, please don't hesitate to ask.

Jacob

[Davy]

Thanks Jacob,

I am going to render the wall using the Dunlop 16kg Ready To Go Premix Render

any tip on how to render using this product. 

[JacobZ]

Hi @Davy,

That sounds like a great plan which will give the wall a very nice finish.

I think the main things that are important are to use the right tools and to follow the instructions closely. Make sure to wet the wall down and give the render a good mix before applying. 

I'd suggest you'll need a rendering trowel, a renderer's hawk, a float some buckets for water, a sponge and some drop sheets as even 20+ year veteran renderers will still drop render from time to time.

It would be worthwhile to have a read of How To Render for some guidance and to not get disheartened if you don't work it out straight away. Once you get into it, you will grow in confidence and skill.

Let me know if you have any further questions.

Jacob

[Davy]

Hi Jacob,

Thanks for all the fantastic information do l need to also get a aluminum screed board ?

[JacobZ]

Hi @Davy,

It would certainly be worth getting one to ensure everything is nice and flat.  

This Masterfinish 1.8m Straight Edge would certainly be a good option.

Let me know if there's anything else I can assist with.

Jacob

[Davy]

Hi Jacob,

I tried  sanding th joint compound off using 150mm 180 grit however  it's barely sanding as l applied heaps.l am concerned that when l apply  the render the raised places will get less render is there a disc sander l can use

[JacobZ]

Hi @Davy,

You could use an orbital sander to speed things up, but the main change I would make is to use a much more aggressive sandpaper such as 40 grit.

As this is a base coat, it will end up getting covered, so there is no real need to be gentle as you are not aiming for a perfectly smooth finish. Just try to remove any hard edges or obvious lumps and the render should cover the rest.

Let me know if you have any further questions.

Jacob