# Rustin's plastic coating (RPC)



## Mogwai101 (7 May 2015)

I am planning on using RPC on a project soon so did some research on this site and see a few references to the surface becoming "critic". Can someone explain what this means please?
Christopher


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## Sgian Dubh (8 May 2015)

I think you must be referring to *this* thread: 

There is use of the word "critic" two or three times, but it's almost certainly a malapropism or simply a misspelling. It should read "critical", and the writer is referring, I think, to the time required for the finish to fully cure rather than to some sort of fault. It may also be a reference to a recoating window that applies to some finishes. For example, some finishes should be recoated within a set time period, e.g., 3 hours, but if this window is missed then recoating has to wait until another window opens up, e.g., 24 hours or more. I'm not sure if this is the case with Rustins Plastic Coating. Slainte.


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## Phil Pascoe (8 May 2015)

+1 There is a gap between your last chance of a chemical bond, and your first chance of an adhesive (mechanical) one. Iirc this applies to RPC - it was a long time ago I used it.


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## Mogwai101 (8 May 2015)

Thank you to Sgian Dubh and phil.p for the responses.
So, if I want to get the best bond between coats, I must leave it for at least "x" hours and not more than "y" hours. "x" is the time for sufficient hardening of the layer laid down and "y" is the time at whcich the layer applied will become "critical" and will only bond mechanically (ie as an adhesive) with the next layer. How do I determine what x and y should be? I assume it will relate to the environment (temperature/humidity) and if I have used a thinner.
Goldeneagle32 back in Nov 2009 suggested that "x "should be greater than 4hrs and that "y" had not been exceeded up to 48 hours. 
I do not see a problem with applying a second and third coat within 48 hrs,but I can imagine that something could interfere with my programme making it impossible to apply additional coats before the "critical" window closes.
Does anyone have experience of what happens if you fail to get the chemical bond due to delaying the next coat till the "critical" phase/time limit has passed? What would be the impact on the finish?


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## Phil Pascoe (8 May 2015)

I seem to remember reading guide lines somewhere. They go along the lines of - if you don't re coat within n hours, you should leave it for n hours. I forget the exact figures. The thing being that you lose the chemical bond if it hardens too far, and to get a good mechanical bond, the surface needs sanding - which you can't do while the finish is soft (you might think you can, but it doesn't work). You can put on two or three coats in 24hrs but it's best not to go over that - I did six in 24hrs and it dimples with spots that stay flat (gloss wise) no matter what, because the solvent in the first layers gets trapped and messes up the surface. I did two bar counters 27 - 28 yrs ago - they are now a bit rough around the edges - if I knew what I know now I'd have put down three coats, told them to be careful with it and left it for two or three weeks before doing another couple.


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## Mogwai101 (8 May 2015)

Thanks Phil.P.
I will contact Rustins and see if I can get some info. I will post it when I have something more to share.
C


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## Sgian Dubh (9 May 2015)

Mogwai101":2peitlqr said:


> So, if I want to get the best bond between coats, I must leave it for at least "x" hours and not more than "y" hours. "x" is the time for sufficient hardening of the layer laid down and "y" is the time at whcich the layer applied will become "critical" and will only bond mechanically (ie as an adhesive) with the next layer. How do I determine what x and y should be?


I can't answer your question because I haven't used Rustins Plastic Coating more than a couple of times, and it was too many decades ago to recall the application procedure! I don't remember, or know, if the finish has time dependent application windows. And a quick look at the data sheets available at the Rustins website about the product didn't inform me one way or the other, saying only that recoating may take place after one hour.

Generally, the best advice I can think of for working with a product new to you is to follow the guidelines supplied by the manufacturer - they usually know best how to use their own products. If Rustins recommended application procedures emphasise time dependent windows, don't ignore the information. Slainte.


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## Mogwai101 (9 May 2015)

Tks.
I will follow the instructions.
But it seems that the instructions are not complete from the GoldenEagle posting. I will follow up with Rustins. Tks or your input.
C


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## sihollies (9 May 2015)

Hi

I finished a project last year which required durable gloss finish, so decided to use RPC and burnishing paste.
I contacted Rustins, as to how to acheive this and this was the reply.

_'Hi

The recoat time is 2hrs. The recoat time for product should not exceed 18 hrs beyond which it should be left for 6 days.

When burnishing to a mirror finish at least 5 coats are applied. After 4 days lightly sand with very fine wet and dry paper and burnish using Rustins Burnishing paste. Rustins Grain Filler can be used to fill the grain prior to coating. Please visit our web for full info.

Customer Services
Rustins Ltd'_

Hope this helps

Si


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## Phil Pascoe (9 May 2015)

Excellent. Pretty much what I said, but I couldn't remember the figures.


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## sihollies (9 May 2015)

I found this:

http://www.rustins.eu/ProdData/Plastic% ... %20PDS.pdf

I do remember that the mixing ratios are critical.
1 part hardener to 4 parts coating.

Hope it helps. 

Si


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## Mogwai101 (10 May 2015)

Thank you Silholies and Phil.P
I have the info now. I will come back err long I hope with some pics t o show for the helpful advice.

Again, many thanks to all contributors.
C


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## jimmy_s (10 May 2015)

There was a post here a few years ago that might help also:

rustins-plastic-coating-straight-from-the-horses-mouth-t61190.html


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## Sgian Dubh (10 May 2015)

jimmy_s":3ks3devw said:


> There was a post here a few years ago that might help also:


That's the thread linked to in my first post, and has been referred to a few times in this thread. Slainte.


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## provenancecoopering (15 Jan 2016)

I've used Plastic Coating successfully for years and I've found it to be ideal for my purposes but the 'critical window' is a big, big issue. Apply a second or third coat at the wrong time and the varnish bubbles up, ruining the work. I've found that the best way (for me) is to wait at least 3 days between coats. If you mix thinners with the varnish to make it flow more easily, then the 'critical window' is even more difficult to judge and I've had problems even after letting the varnish dry for a week!


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## blackrodd (15 Jan 2016)

Found this, almost from the horses mouth,=
rustins-plastic-coating-straight-from-the-horses-mouth-t61190.html

Regards Rodders


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