What is causing my gel stain to turn cloudy?

I would sand again. They sell preconditioners that open up the grain so stain will be accepted evenly. Not sure if this is the problem or not but it might be worth a try. Also, what did you sand with? You want to start with lower number grit and work your way up to 220.

Then...You will want to add a preconditioner so that the stain can soak in evenly throughout the wood but this only works on raw wood. Please check out my post on a bench that I refinished. It was the best stain job I have ever done. It is so smooth like a piece of furniture you would buy so I am recommending this method. Gel stain is a little different though so you will have to adjust accordingly.

Also, The wood in my project was walnut so it might accept the stain a little different but the process will be the same. Follow the directions in the post especially where it talks about applying the preconditioner and the wait time afterwards before applying stain. In that post I used Waterlox. You can use whatever sealer or finished topcoat you want. That was just the one we like and prefer. Good luck!

https://karupp-did.net/bench-part-2/

I am wondering what color stain you are using over a dark table. You can only go darker not lighter so maybe that is the problem. It also looks like you didn't wipe the gel stain with the grain of the wood but that may be just what the picture looks like and you did wipe the gel stain with the grain of the wood. Gel stain normally requires more than one coat as well. Do not seal the table until you are happy with the results.

Other than already suggested, perhaps your gel stain was old.

It almost looks like you sanded against the grain.

It could be a temperature issue. It needs to be above 50 for a gel stain to really work well. It could also be a humidity issue. High humidity could prevent the stain for have a prime appearance. It could have also separated during storage.

Looks as though you need to sand down to bare wood and in the direction of the grain. It will be a bit more difficult because you said the grain is going in different directions to join at the middle. You can protect each section from the sandpaper going the wrong way by masking it and using newspaper to protect the areas you're not sanding. Use coarse sandpaper, then more fine to finish off.

Here's what I found on the internet bout the clouding you asked about.

The most common reason is an incompatible stain. For example, using a water-based topcoat over an oil-based based stain. When the top coat is applied, the oil in the stain seeps up through the finish and reacts with the acrylic causing a chemical blush. Good luck and I hope this helps you a bit.

you have not cleaned & sanded surface enuf for new application and depending on type of wood some release tannins so will need to pretreat/seal wood before trying to achieve a certain finish or color/stain; also make sure conditions are good for applying any product -- Humidity,moisture,excessive heat or cold are all huge factors

You need to sand with the grain. If you were looking for a darker color then gel stain can be used over existing stain. If there is a clear coat you would need to lightly sand just to remove the gloss. If you were looking for a lighter color then the finish would need to be stripped. Basically gel stain does not absorb into the wood but bonds to the surface unless the the old finish is stripped. Hyere are some instruction for Minwax polyshades but would apply to any good gel stain.

https://www.minwax.com/how-to-finish-wood/change-stain-color-with-polyshades/

Did you lightly stir the stain? If you shook it up this could be causing the problem. It looks lighter than your table which could also be the problem.

I think you would need to strip it because it must of being old