Matting agents

[fv1609]

When I have asked before about converting gloss paint to matt, the suggestion has been to add chalk. Not having any chalk I have tried talcum powder, about one third powder to two thirds paint by volume.

 

This seems to have done nothing for the finish, just made the paint a bit thicker. Talc is hydrated magnesium silicate & chalk is calcium carbonate is it a chemical issue? I had assumed it was to do with the particle size.

 

Anyone experiences of matting agents commercial or homemade? When I search for these things its mainly about model makers & arty-crafty things.

[Mrs Hardyferret]

Good Morning Clive

 

Have passed on this info to Jerry, as one of our customers is Farrow & Ball, the paint people. He will see if his contact in the paint mixing dept can help. Will keep you posted.

[fv1609]

Yes he has rung me thanks, the comms system your end seems fully intergated to developments, you obviously run a very smooth operation ;-)

[Enigma]

So come on, spill the beans....or paint.

[Richard Notton]

Anyone experiences of matting agents commercial or homemade? When I search for these things its mainly about model makers & arty-crafty things.

 

Just go to any commercial paint supplier Clive and ask for matting agent, probably nearest you would be Acron:

http://www.touchsouthampton.com/business/list/bid/2365551

There is another that was at Shirley in Salem St, can't remember the name.

[ackack]

I used to buy synthetic paint and a separate matting agent from Bancrofts in Worcester, they have branches all over. Useful in you could mix it to your own requirements. Messy work though much easier to buy it ready matted.

[Jessie The Jeep]

I believe 'Ground Glass' is also used as a matting agent.

 

Steve

[fv1609]

Thanks for all the suggestions. Buying it ready matted is not an option because it is not a standard colour & I have to mix it myself, which is something I am quite happy doing. I have painted two vehicles in homemade colours rather than ready bought stuff.

 

Whenever I see paint very cheap I buy it on the basis that I can paint a shed, gate etc or use it as the basis for mixing it to paint a vehicle even if only for an undercoat.

 

The paint I am trying to create is 'Rustoleum Green' used in 1969 by the RUC on their pigs, Shorlands & some Commers. Rustoleum are unable to identify the type of green they had at that time. I am lucky in that I have a Shorland that was originally Rustoleum Green (they were contrary to popular belief never grey) I have been able to expose 2 square inches of undamaged perfectly preserved paint. But taking the vehicle that has not been driven for 10 years to a paint dealer is not an option. Besides I am too mean to buy new & want the satisfaction of mixing it myself for next to nowt.

 

The funny thing is that when the RUC painted the pigs Light Admiralty Grey for a brief period in 1962 I received lots of criticism when I displayed it in this colour. Recently I have shown it in a rather odd surplus green there has been no comment, but I know it is wrong.

 

The colour is a dull emraldy green, I can achieve this with Light Brunswick Green, Victorian Green, Dark Admiralty Grey, Light Stone & Black. The first two are gloss the last three are matt but the mixture is far too glossy. These have been purchased in 1-gallon cans for £3-£5 or found at the tip, which will be quite an economical way to paint a vehicle.

 

Now when I eventually get this match to Rustoleum Green it will look rather awful but I will know it is correct & that's what counts!

[Richard Notton]

Thanks for all the suggestions. Buying it ready matted is not an option because it is not a standard colour & I have to mix it myself, which is something I am quite happy doing. I have painted two vehicles in homemade colours rather than ready bought stuff.

I don't know if you realise Clive, but none of the commercial suppliers carry any colours at all. They have a stock of base and than add pigment to spec for standard colours like BS4800, BS381C and RAL.

 

However, they can therefore just as readily make any colour you want; I have always dealt with Express Paints in Dundas Spur commercially, take in a couple of square inches of the colour you want and they'll make it up on the spot, no extra charge. You can then define matting in anything from full gloss (no agent) to full matt or indeed take a tin of matting agent and fiddle yourself. They know the proportions to give the standard finishes though from matt, eggshell, satin, silk and full gloss of course.

[fv1609]

Richard, yes I realise it is mixed to requirement & I can see that a standard colour would present no problem. What I am intrigued to know is how it is matched to a sample. Is this done on the basis of some spectrometer reading or are there ranges of chart samples or is it guessd at & then pigments mixed to bring it into match?

 

I was having a MOT today & asked if there was anybody round here or Salisbury direction & was told no, they have to got to Autopaint in Burseldon. That is on my well worn path to visiting my mother, so any experience of them or I suspect it might just be a cellulose paint place?

[ackack]

If you go to Cromadex (who have branches all over) with a sample they can optically view the sample and display its colour coordinates on a PC.

They can then mix the paint for an exact match in any strength of gloss/matt.

A perfect system which I use.

Otherwise you will have to look at many colour charts available and select the nearest.

If you are using known colours to make your Rustoleum Green and some are gloss why not replace those with matt and you can still mix your own colour.

[fv1609]

why not replace those with matt and you can still mix your own colour.

 

Yes I see what you mean but if I was going to have to buy new paint, I might as well get what I want mixed up for me. The original idea was to use stuff that I had in stock for reasons or economy & satisfaction. But I may have to give up & get it matched & mixed in matt.

 

I like the analytical way of matching from Cromadex rather than trying to match against a small patch. But there are no branches of Cromadex round here. The other problem is the bare patch of paint is on the wing of the Shorland & I don't want to have to take the wing in for a match. I will see if there is some way I can cleanly remove a patch of the bonnet & carry that around!

 

But first to investigate the matting agents, but if the stuff is a silly price relative the amount I have to use may give up on that idea & I don't know how much it dilutes the colour density.

 

[ackack]

I can't remember how much matting agent to add, I think it was about 50% for 100% matt paint and pro-rata. Also I seem to remember that it was similar in price to the paint.

And yes the colour of gloss paint does look different to matt ( the actual hue should be similar, just the lightness is different) and gloss being reflective will be noticably more colourful. I have one colour mixed in full gloss and full matt and you would think it is a different colour. Often the paint formula is different depending on the gloss level required.

Don't forget the visible colour of something is actually the colour of light which is being reflected by it. White is white because it is reflecting all primary colours equally, black is reflecting no light ( in theory) but there are hundreds of shades of black due to impurities in the paint, if it were really pure you wouldn't be able to see the item. A glossy surface such as green will reflect all green light from the light source including yellows if it is an olive colour giving it a rich colour, matt paint not being very reflective will appear rather drab hence it is ideal as camouflage paint! And just to be awkward the same paint sample can appear a different colour according to the colour of the light source, a warm glow from a summer setting sun will cause matt paint to look very different to that during midday in bright sunlight, browns and greens are particularly affected. Paint that is in the sun will look different to that in the shade, matching paint is a nightmare at the best of times, and then there is colour-blindness!

Paint will fade in strong sunlight so paint mixed to the same spec a year later can look different. Also there is a distance effect with colour, in other words at very large distances (many miles) all colours will tend to move towards black.

Henry Ford had the best idea, "we can do it in any colour as long as it is black"

[Richard Notton]

Richard, yes I realise it is mixed to requirement & I can see that a standard colour would present no problem. What I am intrigued to know is how it is matched to a sample. Is this done on the basis of some spectrometer reading or are there ranges of chart samples or is it guessd at & then pigments mixed to bring it into match?

As you see Clive, some have a digital gizzmo for matching and some have an expert who does it by eye, I have to say Express do it the human way and have never failed yet.

I was having a MOT today & asked if there was anybody round here or Salisbury direction & was told no, they have to got to Autopaint in Burseldon. That is on my well worn path to visiting my mother, so any experience of them or I suspect it might just be a cellulose paint place?

I forgot Autopaint, they're on your route, I can only find Cromadex in Portsmouth:

Unit A14

Railway Triangle Industrial Estate

Walton Road

Portsmouth

PO6 1TN

 

Tel: +44 (0) 2392 201356

 

Don't think you'll find cellulose anywhere without a struggle Clive since that frightfully nice EU banned it a few years ago, then chromate based etch primer, then red oxide which is now "red-brown primer" and definitely different.

 

[ackack]

most autofinishing paint stores still stock cellulose it seems to be prefered by body shops.

As for other paints containing so called banned chemicals, they seem to be still stocked by the larger companies, red-oxide primer I buy is full of phosphates etc and is as red as you can get. I have never come acros any water based paints yet. I know where you can still buy lead primer, its orange in colour and 5litres weighs a ton!

[fv1609]

I found a stockist of matting agent "about £20 a litre" reckons about 30-40% needs to be used to transform from gloss.

 

Although my attempts to used talcum powder met with no success, but I found a stick of chalk ground that up & mixed it into some gloss paint & it has matted it down. Understandably it lightens it & makes it a thicker mix. I need to experiment to see what ratios are required.

 

Anyone any ideas where I can get powdered chalk? Is it used in maybe the building trade, horticulture, pharmacies etc? Just need a cheap & easy source.

[Richard Farrant]

Clive,

 

What about French chalk as used by tyre fitters, at least they used to use it on tubes.

 

Richard

[fv1609]

Clive,

 

What about French chalk as used by tyre fitters, at least they used to use it on tubes.

 

Richard

 

 

Tyre fitters with tubes, you're going back a bit! French chalk, looked that up & says it is powdered talc (= hydrated magnesium silicate) but chalk is calcium carbonate.

 

Now the talc experiment didn't work, the chalk did. But I was using a stick of blackborad chalk rubbed on sandpaper, but I see that is different from "chalk" as it is calcium sulphate. So still not sure, but I wonder does the talc dissolve in the paint whereas chalk is less reactive?

 

 

 

 

[Richard Farrant]

Clive,

 

I hastened to add another line on my previous message, just in case french chalk was not suitable, why not go on the Downs to a quarry, or chalk pit and get a good clean lump, then grind it down and sieve it out. You would need a lot of chalk sticks otherwise!

 

Richard

[fv1609]

why not go on the Downs to a quarry, or chalk pit and get a good clean lump, then grind it down and sieve it out. You would need a lot of chalk sticks otherwise! Richard

 

But will I need a licence from the Dept for Elimination of Farming & Rural Affairs? Even so I would have to go up on the downs, lot of effort even before the grinding & seiving. I might even try a range of other powdery things eg flour? plain or self-raising? I suppose at my age it ought to be self-raising, just to be on the safe side

 

[fv1609]

So still not sure, but I wonder does the talc dissolve in the paint whereas chalk is less reactive?

 

Thinking about it, the talc probably is dissolving & simply making the paint thicker. The role of talc is to absorb perspiration around certain parts of the body so it must be soluble.

 

Now the challenge is to find a cheapo source of powdered chalk, anyone any (sensible) ideas?

 

 

[Richard Farrant]

 

Now the challenge is to find a cheapo source of powdered chalk, anyone any (sensible) ideas?

 

 

 

Clive,

 

Would lime do? After all it is a product of chalk. Should get it in builders merchants by the sack, any left over is good for absorbing oil spills.

 

Richard

[fv1609]

Richard

 

Lime is Calcium Oxide I think, but Limestone is natural Calcium Carbonate. It's a thought though.

 

But I have been googling & it has since Roman times at least been & still used in paint. But as for a cheap source, who would have thought a pet supplies for tortoise & snails:

 

http://cgi.ebay.co.uk/TORTOISE-SNAILS-CALCIUM-CARBONATE-LIMESTONE-FLOUR-400G_W0QQitemZ280097007870QQcategoryZ1285QQtcZphotoQQssPageNameZWDVWQQrdZ1QQcmdZViewItem#ebayphotohosting

And in my price range! Bit better than matting agent at £20 a litre when I would have needed possibly 3 tins!