Iron Contamination Blocker Additive

Iron contamination, seen as black dots in the wood, is a reaction where tannin, iron particles and water come together. The acids and water together cause a strong corrosion of the iron particles, which turn black and cause black spots in the wood. So it arises when three elements come together:

• Wood containing tannic acids/tannin or acetic acid (among others Oak, Chestnut, Walnut, Merbau, Western Red Cedar and Douglas);
• Iron particles in the wood;
• A waterborne finish.

Is one of the three missing? Then the black dots will not arise.

The most common causes of iron particles/dust in the wood are:

• Working with metal in the same room. Think of an interior builder who processes metal and wood in the same workplace, or a plumber who has to make a custom pipework during the renovation.
• Sharpening chisels in the immediate vicinity of the wood.
• Brushing with steel brushes.
• Iron particles from grinding nets.
• Sanding down metal corner profiles of convector pits.
• Sanding nails in a tapis floor.
• Defective bearings in sawing, planing or sanding machines.

Choose to add Iron Contamination Blocker #0091 Additive if you suspect iron contamination may occur. Use Iron Contamination Blocker or make a test in any case in these situations. Once the black dots have formed, this is an irreversible process. The only solution is to sand the wood bare and finish it again. This time with the addition of Iron Contamination Blocker. This is extra work that should be avoided.

No, it isn’t. The effect of Iron Contamination Blocker #0091 Additive is intended for neutralizing/preventing black dots when iron particles/dust has ended up in the wood. The large thick nail that is in the wood will oxidize over time due to the effect of, for example, mopping water.

No, you can’t. Due to its chemical composition, Iron Contamination Blocker #0091 can only be added to STEP Primer Warm #6130, STEP Primer Natural #6090 and SKYLT Original #5510.

When added to other varnishes, the varnish will break. Sometimes this is visible, in other cases it is not. STEP Sealer #6100 Tropical Wood will immediately shift. Other varnishes give an undesirable change in viscosity or viscosity gradient.

In this case, change the first layer of the system. Use this table as a guideline.

Is your option not listed here? Then call for advice.

No, you can’t. These are not water-based products, and therefore cannot be mixed with Iron Contamination Blocker. Moreover. ROYL Oil does not require the use of Iron Contamination Blocker. Because ROYL Oil is a 100% water-free finish, the reaction that causes the black dots will not occur. With SKYLT Recoatable Colour Oil, Iron Contamination Blocker can be added to the first layer of varnish. This is definitely recommended when directly varnishing over SKYLT Recoatable Colour Oil. Then use SKYLT Original #5510. After 24 hours drying of the SKYLT Recoatable Colour Oil, the chance of black dots will be much smaller, but even then, it cannot be completely ruled out.

This is not possible with SKYLT Original. After all, this is a 2K product, which can no longer be used after the processing time of 2-3 hours.

The additive will retain its effect for a few weeks in STEP Primer Warm #6130, STEP Primer Natural #6090 and ROYL Reactive Stains. Mixed product can therefore be used on a subsequent job. Make sure you clearly mark the packaging of self-mixed product with the production date. After a few weeks, dispose of the unused product residue as chemical waste.

When the additive is added to the varnish, the wood will turn slightly darker than when the same varnish is used without this additive.

Especially with STEP Primer Natural #6090 and SKYLT Original #5510, it is good to take this into account. After all, these varnishes have been developed to give the wood a light or even invisible protection. Therefore, it must be a conscious choice to use the additive.

Water-based joint sealant can also cause iron contamination on tannin-rich wood. Especially if no stainless steel nails are used. Because the joint sealant is sanded off afterwards, it is advisable to use STEP Primer Natural, STEP Primer Warm or SKYLT Original in combination with the additive as the first layer of varnish.

For several reasons, it will often be the better choice to finish such a floor with a water-free system.

No, that is not the case. Unless parts of the first layer have been sanded off, it is not necessary to add Iron Contamination Blocker in subsequent layers of varnish.

No, it won’t. The colour of the stain is not affected by this.