1. Which coating thickness must I apply for the primer and coating coats?

The optimal wet thickness of the coat is very dependent on the type of product and is indicated on the technical sheets which are available for every product.

 

Optimal wet thickness of the coat
Processing the product is easiest and offers the best protection when the products are applied within the optimal wet thickness of the coat (indicated in the technical documentation sheet for the product).

 

Too low wet thickness of the coat
Properties such as gloss retention and product life of the product greatly diminish when the products are applied in a too thin (and/or strongly thinned) wet thickness of the coat.

 

Too high wet thickness of the coat
The drying is negatively influenced whenever very high wet thicknesses are applied to the coat. Properties such as gloss retention and product life of the product greatly diminish. The product can also show signs of wrinkling.

1. What is the optimal processing temperature for the priming and coating coats?

The optimal processing temperature is very dependent on the type of product and is indicated on the technical sheets which are available for every product.

 

The drying of the product is negatively influenced at temperatures lower than the indicated minimum. Properties such as product life and bonding of the product greatly diminish. 

 

At low temperatures or cold nights, maintain a longer paint over time between the various coats (more than 24 hours)

3. The paint doesn't dry properly, why does this happen?

The temperature is too low for good drying, there is insufficient air circulation or the humidity is too high. The time required for full-hardening is dependent on the temperature in combination with the humidity. At very low temperatures and high humidity the drying process can almost entirely stop. (Sun) light is also an important factor in the drying process. The paint dries badly without light.

4. There are blisters in my paintwork, how do I prevent this?

Blisters in paintwork

This can be caused by painting on a too hot substrate (paint cooks) or by immediately placing a cold object in the sun after the application of the paint. This can especially occur on steel substrates after a cold night. Using the wrong thinner can also be the cause.

 

 Blistering can also occur on “coarse grained” wood (e.g. meranti). The air enclosed in the pores can expand after warming-up and cause blistering. Prevent direct exposure to the sun after application of the coat of paint.

5. How much thinner can I use?

Preferably use as little thinner as possible. If necessary never add more than the maximum prescribed percentage and type of thinner.

 

Too high thinner percentages
The required wet thickness of the coat of the product is not achieved. If the wet thickness of the coat is applied too thinly, properties such as gloss retention and product life greatly diminish. This can also lead to blistering. At very high thinner percentages the paint is no longer workable and may cause the paint to sag and/or drip from the brush.

6. The paint comes loose, why does this happen?

If the paint comes loose from the substrate (peels off), this can generally be blamed on no or insufficient pre-treatment of the substrate (grease, insufficiently sanded, left behind sanding dust, etc.). It can also occur that a paint does not “fit” in the paint system.


Painting on a damp substrate (condensation after a cold night) can also lead to detachment.


Detachment problems can be caused by polyester filled spots. Polyester filler easily absorbs moisture (it is hygroscopic).

7. The paint wrinkles, why does this happen?

Wrinkles

 

The cause of wrinkling is usually an insufficiently hardened undercoat or the use of incorrect thinners.

The wrinkling of the paint can also be caused by the application of a too thick coat (mostly on horizontal work)

8. How do I prevent streaks in my paintwork?

Streaks in paintwork

Too little paint on the brush, or processing the products under the optimal coating thickness, cause too quick drying. This leads to brush streaks which do not disappear.

By adding thinner the optimal coating thickness is no longer achieved with the result of even faster drying and streaking .

If the can is open a part of the thinner evaporates and the paint is too thick for processing. In that case a small percentage of thinner may be added. Cold circumstances can cause the paint in the can to be thicker.

The addition of thinner under cold circumstances can cause the paint at higher temperatures to be too thin to process.

9. The paint shows “fish eyes”, small crater-like openings in the finish.

This can be caused by the presence on the substrate of (condensation) water, grease, wax, silicone or other contamination. Silicones can be found in all kinds of substances and materials, such as car and boat wax, skin creams and household cleaners and such like.

The paint draws back in long streaks (cissing). This mostly occurs by the application of the paint on an unsanded or insufficiently sanded substrate treated with a hard high-gloss paint (for instance a 2-component polyurethane coating). In both cases the applied coat of paint should be removed before drying and  the surface should be degreased with a suitable cleaner and degreaser. Such surfaces with (a 2-component) high-gloss paint need to be well sanded beforehand.

10. The paint already loses its gloss after only a few weeks, why does this happen?

Loss of gloss

The paint already loses its gloss after only a few weeks, why does this happen?

Early loss of gloss can generally be blamed on the application of insufficient coating thickness. This causes the paint or varnish coat to lose its original gloss faster than normal because these too thin coats are less resistant to effects from outside such as UV light. Also the polishing and/or cleaning with aggressive scouring agents can lead to early loss of gloss.

In all cases apply a full coat of varnish or paint again.

11. There are water stains in my paintwork, how should I treat them?

Water stains occur for instance after a shower on fresh, insufficiently dried paint or varnish. During the evaporation of the rainwater dissolved components of the water (salts and other pollutions) have penetrated into the top coat and lead to discoloration and staining.

After drying and hardening this damaged coat needs to be sanded smooth again and given a new coat.

12. I have used the wrong hardening agent (B-component) with the base component (A component), what should I do?

The paint needs to be removed in its entirety.

13. I have forgotten to add the hardening agent (B component), what should I do?

This causes the paint to not dry or dry slower (depending on which hardening agent is used). The paint needs to be removed in its entirety.

14. What do I use for sanding?

The finer the sanding the more beautiful the final result. For finishing, use at least sandpaper with a thickness of P360, with substrate a thickness of P220 is sufficient.

Coarse sanding (thickness P080–P120) does not mean that the bonding of the paint coats will be better.

15. How do I know and measure that it is not too damp to paint?

The relative humidity (r.h.) needs to remain under 85% during application of the paint. This is very dependent on the temperature of the surroundings. There are standard tables available for this. You can measure the humidity with a dew point metre.

Wood may not contain more than 18% moisture. A too high percentage of moisture interferes with the bonding and the drying of the paint. This can also lead to moisture blisters.

16. How do I know whether I am above or below the dew point if I do not own a measuring device?

You measure the dew point by taking a cigarette paper and pressing it against the surface to be painted. If the cigarette paper stays put you are below the dew point.

I want to switchover from a 1-component coat to a 2-component coat, is that possible?

Yes, you can switchover from a 1-component coat to a 2-component coat. First apply an intermediate coat of Nelfaprime Tropic RW ZF or Nelfaprime Multiprimer.

18. I want to switchover from a 2-component coat to a 1-component coat, is that possible?

Yes, you can switchover from a 2-component coat to a 1-component coat. First apply an intermediate coat of Nelfaprime Tropic RW ZF or Nelfaprime Multiprimer.

19. Is a paint containing zinc phosphate suitable for under water use?

No, never use active corrosion-inhibiting paints containing pigment under water (so also never Nelfaprime Tropic Lead oxide). Nelfaprime Tropic Iron oxide may be used, this does not contain active pigment.

20. So I always need to sand between the various coats?

It is desirable to sand between all coats. It improves the final result and benefits the bonding. Old coats of paint (older than 4 weeks) must always be sanded.

21. Can it do any harm to add other substances such as Owatrol etc.?

Sometimes other substances such as Owatrol support the properties positively, however sometimes not at all. Always take the specifications of the product into consideration. A maximum amount of thinner is indicated in the technical documentation sheets. However, the guarantee lapses if other substances are added.

22. How much paint do I need?

The amount of paint which you need can be calculated using the following formula.

Vol% solid substance x 10 = .. x m2/l

coating thickness in micrometres.

23. How clean does the substrate need to be to apply an epoxy coat?

The substrate should be clean, dry, free of grease and firm.

New steel:

Rust and mill scale need to be removed by means of blasting (level of cleaning SA 2.5). If blasting is not possible, remove rust by hand by means of rotating sanding brushes, sanding discs, rust brushes to a level of cleaning SA. 3. Then degrease well.

Maintenance and repair:

Remove oil, grease etc., with cleaning agents appropriate for that purpose. Remove salt and other contaminations with a high-pressure spray. Prepare damaged parts by removing rust by hand by means of rotating sanding brushes, sanding discs, rust brushes to a level of cleaning SA. 2. or by means of blasting to a minimum of SA 2, but preferably SA 2½.

25. How clean does the substrate need to be to apply an epoxy coat?

Yes, a polyurethane coating can be directly applied over an epoxy coating provided that the drying time of epoxy is taken into consideration, see the technical documentation sheet concerning drying time. Rule of thumb is that the second coat may be applied immediately within 14 days. After 14 days the surface must first be sanded.

26. Can an alkyd paint from Nelf be applied over an alkyd paint from the competitor?

It is preferable to keep to one system from the same supplier. If the types of alkyd paints correspond, then this can possibly be painted over with a Nelf alkyd. However, no guarantee is given for this.

27. How penetrating is Nelfamar Penetrating Hold Paint?

The hold paint does of course not penetrate into steel, but penetrates well into old paint layers and/or rust spots still remaining on (steel) substrates. In the last case such a treatment is only of cosmetic importance and then only has a relative durability.

28. At which temperature can I still use the summer hardener?

Do not process the standard (summer) hardener below  5°C and above an RH of 85%.

29. At which temperature must I use the winter hardener?

Use the winter hardener at temperatures between -5°C and 5°C. Do not process above a RH of 85%. The temperature of the substrate must lie at least 3°C above the dew point. There may also be no ice crystals on the surface to be treated.

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