Pre- or Post-Mix | What’s the Difference?

As with many renders and plasters, ROCKCOTE products are available in both pre-mixed and dry renders. With pre-mixed, you simply scoop it out and apply, whereas post- or dry-mix powders need mixing on site.

Both have their benefits, but is one better than the other? Well, that depends entirely on you job, your location and what you are trying to achieve.

Let’s take a look at to pros and cons of each:


Pre-mixes are incredibly convenient. There’s no need for extra mixing equipment, no effort involved and they’re ready to go straight out of the bucket. They are also excellent specialist renders, better for smaller jobs and specific applications. Acrylic renders need to be premixed due to their formula and ingredients, but provide an incredibly durable, flexible finish. This flexibility makes them less prone to cracking, more durable and lower maintenance.

Because they are precisely pre-mixed for you, the product will always be consistent. You will get the same texture, the same colour and the same finish every single time. If you are planning to leave your render bare, without painting over the top, this can effectively do two jobs in one, giving you an even veneer that is also your plaster foundation.

If your job is only small, the pre-mixed option also saves a great deal of time. This is handy for you, but also saves you money if you are hiring a plasterer or tradesperson.

Because of their convenience, flexibility and ease of use, pre-mixed renders are best-suited to home renovators and DIY projects.

The downside of a pre-mixed render is that one pack doesn’t go as far. While it does provide certain savings, it also costs more per square metre and requires more units to be bought, picked up or delivered. On a smaller project, these positive and negative costs can even out, but for a large job, pre-mixed render can really add up.

Consistency can occasionally also work against you. While you can achieve an even texture with pre-mixed render, some plastering techniques work far better with a dry-mix plaster, though these usually require the skills of an expert.


Dry-mix cement rendering is a hardy solution for external plasterwork. It is incredibly cost-effective for larger areas and allows you more time to work. Though it does dry out quite quickly and you need to mix in batches, rather than in bulk, you can lightly spray it down to moisten it and make it more workable. Be careful not to over-water though, as this will result in your entire job collapsing.

Dry-mix works particularly well on masonry surfaces, such as brickwork or cinderblock work. The downside of this is that it will also require plastering mesh if you are applying to a smooth surface.

Cement or concrete plaster is excellent for painting. More absorbent than pre-mixed renders, the paint binds much better with the render surface, making application easier and longer lasting.

Dry-mix is generally better used by professionals. It isn’t as forgiving as a pre-mix, takes extra labour and knowledge to mix to the correct consistency and needs a bit of patience and experience to create the ideal finish. However, those same professionals can use a variety of techniques to create unique, creative and expressive finishes that are hard, even impossible, to replicate in pre-mixed acrylic renders.

If you plan to colour your render, dry-mix isn’t the ideal way to do this. Because you are mixing on site, by hand and in batches, there is a lot more risk of varied colour and texture. This can also be a bonus, with these irregularities adding to a more rustic, bespoke, artisanal look. This works particularly well with Mediterranean-style projects or areas surrounded in natural materials or surroundings.

The size of your job, the area and location you are rendering, and the desired finish are the key aspects of choosing one render over another. Once you have this information, give your ROCKCOTE expert a call to match the best product to your needs.