Removing varnish from sandwash

[HTC]

I am at my wits end with a builder.

 

I have had new sandwash applied to my driveway. The sandwash job went fine, but the builder then used an old wet roller brush to apply varnish on top which was supposed to protect the sandwash from stains.

 

The result was the varnish went a milky white and the whole area is a mess. To make things worse he tried to recolour by using some black wood stain! :facepalm:. It all dried and now he is trying to remove the mess with turpentine without success.

 

Is there a better/stronger product available that I can suggest that will remove the varnish?

[sometimewoodworker]

Varnish going milky white has nothing to do with the thing that was used to apply the finish, exactly why it went like that is difficult to diagnose but one possible cause is moisture in the item being coated, there are others such as a reaction to the underlying material.

 

As you have already found out turpentine will do nothing for a cured surface, it and most other thinners will only work on uncured or semi cured finishes. AAA is nasty stuff to breathe but is one of the stronger thinners though it probably won’t work either you can get it everywhere so it’s worth trying. 
 

You say varnish but there are many things called varnish so that doesn’t help much. It could be a polyurethane with UV retardant.

 

Anyway you may be able to get it off using a paint stripper. Knowing exactly what was used I would contact the manufacturer or a specialist shop to ask for advice.

 

 

[ChipButty]

hydrochloric acid usually does the trick leave it on for 15 minutes then jet wash it off

[HTC]

I still have the cans of the product applied. I'm not at my place for a few days but I'll check what it is an post when I know.

 

I remember the guy taking the roller out of a bucket that had water in it and then he when straight to work.

 

The sand wash was cleaned with acid after it was first done and left to dry for a few days.

 

After seeing the milky effect I took a small amount of the product and mixed it with thinner like the builder did. No problem.

 

I then added some water and it went white straight away.

 

Anyway, I'll check what the product is and post later.

 

Any recommendations for a paint stripper available here? I'll try a small section to see what happens.

[sometimewoodworker]

34 minutes ago, HTC said:

I still have the cans of the product applied. I'm not at my place for a few days but I'll check what it is an post when I know.

 

I remember the guy taking the roller out of a bucket that had water in it and then he when straight to work.

 

The sand wash was cleaned with acid after it was first done and left to dry for a few days.

 

After seeing the milky effect I took a small amount of the product and mixed it with thinner like the builder did. No problem.

 

I then added some water and it went white straight away.

 

Anyway, I'll check what the product is and post later.

 

Any recommendations for a paint stripper available here? I'll try a small section to see what happens.

You probably have the cause of the milkiness, solvent finishes and water are not a good idea. 
 

There is a chance, small but still a chance, that given a few days of sun the milkiness may clear.

 

The acid mentioned above may work. I would test on a small unobtrusive area first. As I haven’t needed to do anything like you need to I can’t advise.

[alacrity]

10 hours ago, ChipButty said:

hydrochloric acid usually does the trick leave it on for 15 minutes then jet wash it off

Look at a pool supplies vendor for purchase. It's not expensive, but potent. Seriously consider PPE when using and maybe diluting before use. Always add acid to water. Not the converse. Using free flowing water from a hosepipe to rinse is preferable in restricted areas.

[sometimewoodworker]

Quote

Solvent-based strippers

How they work. Solvent-based strippers are by far the most common type of stripper used today. The reason they are so popular is because they work fast, and a small amount of stripper goes a long way. Methylene-chloride based strippers are very popular, and work very well on all resin types and thicknesses. Other types of solvent strippers include N-methylpyrrolidone (NMP), dibasic esters (DBEs) and combinations of toluene, acetone and alcohol. Solvent-based strippers only work when they are wet, so taking steps to slow the evaporation of the solvent is important for product performance. Once the coating residue and any remaining stripper have been removed, cleanup consists of scrubbing with soap and water followed by rinsing with clean water. Using a high-pressure washer is recommended.

Source of quote above 

[VocalNeal]

On 12/22/2019 at 9:30 AM, ChipButty said:

hydrochloric acid usually does the trick leave it on for 15 minutes then jet wash it off

Also known as Muriatic Acid. Used for etching concrete prior to painting. 

[mogandave]

Do you have a GOOD pressure washer? Any thing you use will likely need to be pressure washed. 
 

Global House has 20l jugs of Hcl 30% and it’s cheap. It might work, I doubt it but it’s worth a try. As sometime in said, try a small area first. 
 

Paint stripper will likely cut it, but will absolutely have to be pressure-washed off. It should also be pressure-washed before you start with the stripper
 

It’s possible (likely?) neither acid nor paint stripper will look uniform when done. 
 

Sand/bead blasting (particularly water-driven) would be best if you can find someone to do it but it will likely be expensive.