Frequently asked questions for

Marine and Protective Coatings

Here are some of the most frequently asked questions with their answers from Marine and Protective Coatings.


Can you recommend a suitable rheology additive for a xylene based alkyd paint?

If you want to use a liquid rheology additive, you can use RHEOBYK-7411 ES (Poly urea) or RHEOBYK-430. These products can be post added. A possible clay based additive is GARAMITE-1958. The mixed mineral technology provides high sag resistance and low viscosities due to strong shear thinning effect. A further possibility is, to combine CLAYTONE-40 with a castor-oil derivative RHEOBYK-100.

What additives do you recommend to stabilyze Zinc dust in solvent-borne system? The additives should keep zinc from agglomerating but not insulate the particles from making good electrical contact.

Due to high density of zinc, we recommend an organoclay to prevent settling. For medium polarity we recommend CLAYTONE-HT for high polarity systems (xylene + alcohols) our first recommendation is CLAYTONE-MPZ. To ensure a homogenous distribution in your paint, try DISPERBYK-102 and/or BYK-9076 with 0.5% in total formulation. All additives have no negative influence on salt spray test and will give no problems with gassing.

Which dispersant agent is your recommendation for fluorocarbon resins? I am interest in all kind of pigments.

For OH-functional fluorocarbon resins dissolved in aromatic solvents or esters, we recommend DISPERBYK-2025 or DISPERBYK-140. The additive dosage is as follows: Titanium dioxide: 2% additive solid on pigment, Inorganic pigment: 10% additive solid on pigment, Organic pigment: 30% additive solid on pigment, Carbon black: 50% additive solid on pigment. DISPERBYK-2025 and DISPERBYK-140 are very good for dispersing most kinds of organic pigments and carbon black. Do not hesitate to contact us for more support.

I am working on a TiO2 pigmented solvent free epoxy. I have found severe loss of hiding while curing. TiO2 disperes fairly well in the epoxy, and even better in the amine curing agent without dispersant, but it leads to loss of hiding. What can I do?

This problem mainly occurs due to flocculation of titanium dioxide. To avoid this kind of phenomena, correct additive and correct additive dosage are both important. Even if it looks fairly well in the mill base. Try DISPERBYK-2152 or DISPERBYK-111 in the epoxy part during the grinding of the pigment. The dosage is 2% of solid additive on titanium dioxide.

We are developing 2 pack polyurethane coatings. Sometimes, the cured coating shows flooding and floating. The problem is worse, when the coating colours are dark: blue, grey, green. Can you give us any suggestion?

Organic pigments like phthalocyanine blue, phthalocyanine green and carbon black are the most difficult pigments to be wetted, dispersed and stabilized. One vital factor is the stabilization by using a right wetting and dispersing additive. If you produce co-grinds, one additive should be able to stabilize all of the pigment and fillers. DISPERBYK-2013, DISPERBYK-2055 and DISPERBYK-2155 are such additives. The next part is the dosage: As a general guide for TiO2 2% sop (solid additive calculated on pigment), for organic blues and greens 30-40% sop and for carbon black 40-100% sop. Often a pigment synergist is needed for phtalo blue and green. We recommend 3-5% BYK-SYNERGIST 2100 on pigment. The synergist should be added in the grind, before adding wetting and dispersing additives.

I am working on an epoxy system, which is highly filled and I run into the following issue: It it very high viscous, but however the pigments and fillers settle. What can I do?

To improve the flow we advice to use a viscosity reducing wetting and dispersing additive. DISPERBYK-142 or BYK-9076 are our first recommendations when it comes to anticorrosive coatings. As a general guide we recommend 2% sop (solid additive calculated on pigment) for TiO2, 5% sop for inorganic pigments and 0.5% sop on fillers. Regarding settling, there are two options RHEOBYK-7410 ET or BYK-430. 1% delivery form calculated on component A is a good starting point. These rheology additives provide excellent shear thinning effect.

I need to disperse a high load of fumed-silica into a liquid epoxy resin to thicken the binder and a rheology agent to stabilize the viscosity, whithout losing good flow properties while processing. Which BYK additives can I use to meet the requirements?

Disperbyk-103 is one of the Wetting and dispersing additive for silicas. This additive gives better flow properties and it is possible to add even more silica to the system due to strong viscosity reduction.

We are developing 2 pack waterborne epoxy anti-corrosion coatings. Now in my lab experience, pinholes are always observed in the coating film. Do you have any ideas? What kind of surface additives do I have to use?

The main reason for pinholes are air bubbles. So a suitable defoamer should solve the problem. We recommend the classic way: Choose BYK-024 as a startingpoint and check on defoaming and cratering. No craters and no defoaming? Try BYK-022 as stronger defoamer. If the defoamer causes cratering it is recommended to apply higher shear forces or try BYK-1710. To enlarge open time use 0,5-1,0% BYKETOL AQ or a surface additive 0,3-0,5% BYK-3455 or BYK-349 will also improve substrate wetting.

What flame retardent additives can you recommend for my intumescent coating?

We cannot offer a flame retardent additive like we do for plastics (e.g. for cable coatings), but we can recommend some additives that improve the performance of intumescent coatings. Even if relatively little amount of wetting and dispersing additives are used for water borne intumescent coatings, the choice here is critical, because of storage stability. We recommend DISPERBYK-2012 or DISPERBYK-2080. These two additives can reduce increase of viscosity over storage. The incorporation of a defoamer will not influence char performance, rather they will enhance the performance because of less air in the dried film. We recommend BYK-015 and BYK-1780.
For solvent borne intumescent coatings we recommend ANTI-TERRA-U 100 or BYK-P 104 for wetting and dispersing and BYK-081 or BYK-1794 as a first choice as defoamers.

We are looking for an additive which prevents our heavy duty epoxy coating from sagging.

In medium- to high-polar systems CLAYTONE-MPZ as a maximum performance organoclay provides thixotropic flow behavior. It will give no problems in processability but good anti-sagging properties. If there is no problem to reach temperatures over 45°C, RHEOBYK-100 is a good choice. As a liquid additive RHEOBYK-430 provides excellent sag control due to pseudoplastic flow behavior and fast viscosity recovery after application.

Our target is to formulate a Polayaspartics top coat, which has a smooth, dull surface. How can we achieve this?

It is a little bit difficult to matt a Polyaspartics coating. Due to the low VOC content, the shrinkage of the coating is very limited. This shrinkage is very important for the matting. That means, you have to use a lot of matting agent, silica, in your system. By using our DISPERBYK-103, you will have the chance to add very high amounts (>10%) of silica in your system. Additive level is approx. 5-10% solid additive calculated on silica.

We are working on different epoxy top coats for water ballast tanks and coatings. Do you have additives to improve the clenability, or to decrease the dirt pickup?

We can recommend BYK-SILCLEAN 3701. It is an epoxy functional silicon macromer. Due to the epoxy functionality, it will be integrated in the paint matrix and this will lead to permanent effect. Both cleanability and dirt pickup will be influenced positively.

What HAPS (hazardous air pollutants) free dispersing agent(s) would you recommend for an 80-90 NVV system? Pigments are dispersed in the 100 epoxy resins with MAK as solvent. The dispersing agents also need to be able to lower viscosity of grinding paste.

Try BYK-9076, DISPERBYK-2152 and DISPERBYK-145. They are all solvent free. DISPERBYK-142 is a 60% Version of DISPERBYK-145.

I am looking for a rheology additive for waterbrone anti corrosive primer / direct to metal coating. Could you advise some of your products, which provide sag resistance and do not increase water sensitivity?

For DTM coatings, often an acrylic dispersions are used. All of our RHEOBYK Types are possible to use in acrylics and they do not increase water sensitiviy. Here we especially recommend RHEOBYK-H 3300 VF and RHEOBYK-H 6500 VF. If you use an epoxy system, RHEOBYK-440 is the first choice and RHEOBYK-7610 the second choice.

Which is the best wetting and dispersing additive for waterborne anti-corrosive coatings? Most of the additive I tested had a negative influence on water absorbtion and corrosion protection.

It is true, almost all wetting and dispersing additives have a negative influence on corrosion protection. DISPERBYK-2080 is the first wetting and dispersing additive which has no negative influence on water resistance. Depending on formulation, it may increase the adhesion and thus anti-corrosion properties. It is recommended for all water borne systems: 2 pack PU, alkyd, epoxy and acrylates. When you are working with organic pigments you should try DISPERBYK-2015, since DISPERBYK-2080 has limited stabilisation properties with organics.

Do you have a rheology additive that will work in a amine grind? All rheology additives I tried are either not working at all or reacting and too thick.

For waterborne amine grinds use 2% RHEOBYK-440. It will not react and gives good rheological characteristics.
In solventborne amine grinds use RHEOBYK-430.

Do you have an additive for antifouling which can replace copper?

We have a running project with promissing first results. Contact us and we will keep you updated on this.

I have a gelletion on epoxy pigment paste during storage. Especially on red and blue colors. What could be the reason and how i can solve it?

Many wetting and dispersing additives contain a lot of anchor groups which can react with epoxy resin. Though this problem is more prominent with organic pigments, because they require higher dosages of wetting and dispersing additives for stabilization. DISPERBYK-2152 is one of the most stable wetting and dispersing additive and it is suitable for organic and inorganic pigments. We provide a starting formulation with DISPERBYK-2152 for epoxy pigment concentrates. Please contact your sales responsible.